{ "schema_version": 1, "site": "https://boringtoolskit.com/", "generated": "2026-07-26", "tool_count": 833, "tools": [ { "slug": "1031-exchange-calculator", "name": "1031 Exchange Calculator", "canonical_url": "https://boringtoolskit.com/1031-exchange-calculator/", "category": "Real Estate", "description": "1031 exchange calculator: capital gains tax deferred and any taxable boot in a like-kind exchange.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "401k-employer-match-calculator", "name": "401k Employer Match Calculator", "canonical_url": "https://boringtoolskit.com/401k-employer-match-calculator/", "category": "Finance & Investing", "description": "Estimate employee contributions, employer match, unclaimed match, and per-paycheck amounts.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/roth-ira-calculator/", "/retirement-planning-calculator/", "/compound-interest/" ], "answer": "Estimate employee contributions, employer match, unclaimed match, and per-paycheck amounts.", "formula": "Employer match = salary × employee contribution % matched up to the employer's limit, applied per pay period. The calculator computes how much your match is worth and how it accumulates with your own contribution.", "example": "A $60,000 salary, 6% employee contribution, 100% employer match up to 6% limit: the employer adds $3,600/year, effectively doubling your contribution up to that limit.", "assumptions": [ "Match is a percentage of salary, capped at the employer's limit.", "The employee contribution qualifies for the match only up to the stated cap.", "Pay periods are annualized for the estimate." ], "sources": [ { "organization": "Investopedia", "title": "401(k) Plan", "url": "https://www.investopedia.com/terms/4/401kplan.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is the 401(k) employer match?", "An employer contribution matching yours, typically up to a percentage of your salary (e.g. 100% of up to 6%). It's free money on top of your own contribution." ], [ "How much should I contribute?", "At least enough to capture the full match — that's an immediate guaranteed return. Most advisors recommend matching, then maximizing other tax-advantaged accounts." ], [ "What does 'matching up to 6%' mean?", "The employer matches your contribution (often dollar-for-dollar) until it reaches 6% of your salary. Above that, the employer match stops." ], [ "Is the match subject to vesting?", "Sometimes. Vesting schedules mean unvested matched money may be forfeited if you leave before a set period. Your own contributions are always yours." ], [ "How is the match calculated?", "Match = your salary × your contribution % × the employer match %, capped at the employer's limit (e.g. 6% of salary)." ], [ "What is the 2025 401(k) limit?", "The employee contribution limit is $23,500, plus a $7,500 catch-up for those 50+. Employer matches don't count toward your limit. Confirm the current year's figure." ], [ "Should I choose traditional or Roth 401(k)?", "It depends on whether you expect higher taxes now or later. Traditional gives a tax deduction now; Roth gives tax-free withdrawals later. Many use both." ] ] }, { "slug": "50-30-20-budget-calculator", "name": "50 30 20 Budget Calculator", "canonical_url": "https://boringtoolskit.com/50-30-20-budget-calculator/", "category": "Finance & Investing", "description": "50/30/20 budget calculator: split after-tax income into needs, wants, and savings.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "529-college-savings-calculator", "name": "529 College Savings Calculator", "canonical_url": "https://boringtoolskit.com/529-college-savings-calculator/", "category": "Finance & Investing", "description": "529 college savings calculator: projected value of monthly contributions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "a1c-calculator", "name": "A1c Calculator", "canonical_url": "https://boringtoolskit.com/a1c-calculator/", "category": "Health", "description": "A1c calculator: estimated average glucose from HbA1c.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "absolute-value-calculator", "name": "Absolute Value Calculator", "canonical_url": "https://boringtoolskit.com/absolute-value-calculator/", "category": "Everyday Calculators", "description": "Absolute value calculator: distance from zero.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-27", "related_urls": [], "answer": "Absolute value calculator: distance from zero.", "formula": "|x| = x if x ≥ 0, else −x.", "example": "|−7| = 7 and |7| = 7.", "assumptions": [ "Standard geometric or arithmetic definitions apply.", "Inputs use the units you choose.", "Results are estimates, not professional advice." ], "sources": [ { "organization": "Standard mathematics definitions", "title": "Arithmetic and geometry formulas", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "ac-btu-calculator", "name": "AC BTU Calculator", "canonical_url": "https://boringtoolskit.com/ac-btu-calculator/", "category": "Construction & Measurement", "description": "AC BTU calculator: estimate cooling capacity needed for a room from area and conditions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "acceleration-calculator", "name": "Acceleration Calculator", "canonical_url": "https://boringtoolskit.com/acceleration-calculator/", "category": "Physics", "description": "Calculate acceleration from the change in velocity over time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/velocity-calculator/", "/force-calculator/", "/kinetic-energy-calculator/" ], "answer": "Calculate acceleration from the change in velocity over time.", "formula": "Acceleration (a) = (final velocity − initial velocity) ÷ time. Units: m/s².", "example": "A car speeds from 10 m/s to 30 m/s in 5 s: a = (30 − 10) ÷ 5 = 4 m/s².", "assumptions": [ "Velocities are in m/s and time in seconds.", "Acceleration is assumed constant over the interval.", "Time must be positive." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "after-repair-value-calculator", "name": "After Repair Value Calculator", "canonical_url": "https://boringtoolskit.com/after-repair-value-calculator/", "category": "Finance & Investing", "description": "Estimate after-repair value (ARV) of a fix-and-flip property using comparable sales. Enter comps and see the blended estimate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/maximum-allowable-offer-calculator/", "/fix-and-flip-profit-calculator/", "/cap-rate-calculator/" ], "answer": "Estimate after-repair value (ARV) of a fix-and-flip property using comparable sales. Enter comps and see the blended estimate.", "formula": "After-repair value (ARV) = average of comparable sold prices + value of improvements. The tool averages the entered comparable prices and adds the adjustment value to estimate the property's value after renovation.", "example": "Comparable sales of $280,000, $290,000, and $295,000 average to $288,333; adding a $10,000 adjustment gives an ARV of about $298,333.", "assumptions": [ "Comparable values are entered by the user from recent similar sales.", "The adjustment captures the uplift from planned improvements.", "Zero-value comps are ignored when averaging." ], "sources": [ { "organization": "Investopedia", "title": "After Repair Value", "url": "https://www.investopedia.com/terms/a/after-repair-value.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is after-repair value?", "ARV is the projected sale price of a property after it is fully renovated, estimated from comparable sales plus improvement value." ], [ "How do I calculate ARV?", "Average the recent comparable sale prices, then add the value your improvements should add." ], [ "Why is ARV important for flips?", "It anchors your maximum-allowable-offer and profit projections. Overestimating ARV is the most common reason flips lose money." ], [ "What makes a good comparable?", "A comparable sold recently, in the same area, similar size, layout, and condition. Adjust for meaningful differences." ], [ "How much does renovation add to value?", "It varies. Improvements should be chosen for what the market pays for, not just what they cost. A strong ARV is driven by genuine, comp-supported uplift." ], [ "Can I use ARV for a refinance?", "Yes — many lenders use an after-repair appraised value for cash-out refinances on flip properties." ], [ "What if I have no comps?", "A low confidence. Without reliable comps, ARV is a guess. Find comparable sales first before relying on the number." ] ] }, { "slug": "age-calculator", "name": "Age Calculator", "canonical_url": "https://boringtoolskit.com/age-calculator/", "category": "Everyday Calculators", "description": "Calculate exact calendar age, total elapsed days, and time until the next birthday.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/date-difference-calculator/", "/business-days-calculator/", "/hours-minutes-calculator/" ], "answer": "Calculate exact calendar age, total elapsed days, and time until the next birthday.", "formula": "Calendar age subtracts complete years, then complete months, then remaining days; total days uses UTC date boundaries to avoid daylight-saving shifts.", "example": "", "assumptions": [ "Dates use the proleptic Gregorian calendar implemented by the browser.", "Total weeks are total days divided by seven and may be fractional.", "Legal age rules for leap-day birthdays can vary by jurisdiction." ], "sources": [ { "organization": "Library of Congress", "title": "Science and Business Reading Room", "url": "https://www.loc.gov/research-centers/science-and-business/about-this-research-center/" }, { "organization": "ECMA International", "title": "ECMAScript Date specification", "url": "https://tc39.es/ecma262/multipage/numbers-and-dates.html#sec-date-objects" } ], "faqs": [ [ "What is an age calculator?", "An age calculator is a free online tool that instantly computes your exact age in years, months, days, weeks, and hours based on your date of birth." ], [ "Does this age calculator store my personal data?", "No. This age calculator runs entirely in your browser and requires no signup or account. Your date of birth is processed locally and never sent to any server." ], [ "How accurate is the age calculator?", "The age calculator is highly accurate, using your exact birth date and the current date to compute your precise age down to the day." ] ] }, { "slug": "air-fryer-time-calculator", "name": "Air Fryer Time Calculator", "canonical_url": "https://boringtoolskit.com/air-fryer-time-calculator/", "category": "Food & Cooking", "description": "Air fryer time calculator: temp and time by food.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "alcohol-dilution-calculator", "name": "Alcohol Dilution Calculator", "canonical_url": "https://boringtoolskit.com/alcohol-dilution-calculator/", "category": "Food & Cooking", "description": "Alcohol dilution calculator: find how much water to add to bring spirits or concentrates to a target ABV.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "amazon-seller-fee-calculator", "name": "Amazon Seller Fees Calculator", "canonical_url": "https://boringtoolskit.com/amazon-seller-fee-calculator/", "category": "Seller & Business", "description": "Free Amazon seller fee calculator: estimate referral, fulfillment, storage, and FBA fees plus net profit and margin , with editable 2026 assumptions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/etsy-fee-profit/", "/break-even-units-calculator/", "/price-increase-impact-calculator/", "/research/marketplace-seller-fee-scenarios/" ], "answer": "Marketplace fee comparison: estimate Amazon seller contribution profit with editable fee and cost assumptions.", "formula": "Referral fee = price × category rate (most categories ~15%). Total fees = referral + fulfillment/closing + other. Net = price − product cost − total fees. Margin % = net ÷ price.", "example": "A $30 item with a 15% referral fee: $4.50 in referral fees alone — before fulfillment and other charges.", "assumptions": [ "The referral rate matches the item's category.", "Fulfillment costs reflect the seller's method (FBA or merchant).", "Returns and advertising are excluded." ], "sources": [ { "organization": "Wikipedia", "title": "Fulfillment by Amazon", "url": "https://en.wikipedia.org/wiki/Fulfillment_by_Amazon" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How much does Amazon charge sellers?", "A referral fee (usually ~15% of the sale, by category) plus fulfillment/account fees. The calculator breaks it down per sale." ], [ "What is the referral fee?", "The percentage Amazon takes from each sale — most categories charge about 15%, but rates range from 8% to 45%." ], [ "What is FBA?", "Fulfillment by Amazon — Amazon stores and ships your products for per-unit fulfillment fees." ], [ "How do I calculate profit?", "Net = price − product cost − referral fee − fulfillment and other fees. Margin % = net ÷ price." ], [ "Do fees vary by category?", "Yes — electronics, clothing, and other categories have different referral rates. Use your item's category rate." ], [ "What costs am I missing?", "Returns, storage (FBA), advertising, and professional plan fees ($39.99/month) — add them for a true picture." ], [ "How do I set a profitable price?", "Work backward: target net margin, add all fees and costs, and price accordingly. Re-run when fees change." ], [ "What fees does Amazon charge sellers?", "A category referral fee (8–15%), optional FBA fulfillment fees, storage, and per-item closing fees for media." ], [ "How do I find my referral fee percentage?", "Amazon publishes a fee schedule by category; the calculator accepts your category's percentage." ], [ "Is FBA worth the extra fees?", "It depends on your price, size, and volume — the calculator models both FBA and FBM paths." ], [ "Does the calculator include advertising?", "It shows the base net from sale fees; add your ad cost and return rate separately for real margin." ] ] }, { "slug": "amortization-calculator", "name": "Amortization Calculator", "canonical_url": "https://boringtoolskit.com/amortization-calculator/", "category": "Everyday Calculators", "description": "Calculate your monthly loan payment and full amortization schedule, and see how extra monthly payments shorten the term and reduce total interest.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/emi-calculator/", "/mortgage-payment-calculator/", "/auto-loan-calculator/" ], "answer": "Calculate your monthly loan payment and full amortization schedule, and see how extra monthly payments shorten the term and reduce total interest.", "formula": "Monthly payment = P × r ÷ (1 − (1 + r)^−n), where P = principal, r = monthly rate (annual ÷ 12), n = number of months. Each payment: interest = balance × r; principal = payment − interest; balance decreases until zero.", "example": "A $250,000 mortgage at 6% for 30 years (360 months): payment = $250,000 × 0.005 ÷ (1 − 1.005^−360) ≈ $1,499/month. Total interest over the life ≈ $289,600.", "assumptions": [ "A fixed annual interest rate applied monthly.", "Equal payments made at the end of each month.", "No extra payments, fees, or rate changes." ], "sources": [ { "organization": "CalculatorSoup", "title": "Amortization Schedule Calculator", "url": "https://www.calculatorsoup.com/calculators/financial/amortization-schedule-calculator.php" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is an amortization schedule?", "A table showing each monthly payment's split between interest and principal and the remaining balance, from the first payment to payoff." ], [ "How is the monthly payment calculated?", "Payment = P × r ÷ (1 − (1+r)^−n). For $250,000 at 6% over 30 years, that's about $1,499/month." ], [ "Why is most of the early payment interest?", "Interest accrues on the full balance at the start. As principal shrinks, the interest share falls and the principal share grows." ], [ "How much interest will I pay total?", "Multiply the payment by the term and subtract the principal. On a 30-year $250,000 mortgage at 6%, total interest is roughly $290,000 — nearly the loan itself." ], [ "How do extra payments help?", "Extra principal payments reduce the balance directly, shortening the term and cutting future interest — often saving tens of thousands on a mortgage." ], [ "Is a 15-year loan better than 30?", "The 15-year has a higher payment but dramatically lower total interest. Choose based on cash flow: the 30-year's flexibility can be offset by making extra payments when possible." ], [ "Does this include taxes and insurance?", "No — the schedule covers principal and interest only. Escrowed taxes and insurance are added to the actual payment." ] ] }, { "slug": "ancient-unit-converter", "name": "Ancient Unit Converter", "canonical_url": "https://boringtoolskit.com/ancient-unit-converter/", "category": "Converters", "description": "Convert classical ancient units: cubit, palm, digit, stadium, talent, and more. See modern equivalents for historical measures. Private, no account.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/unit-conv/", "/liters-to-ounces/", "/scientific-notation-converter/" ], "answer": "Convert classical ancient units: cubit, palm, digit, stadium, talent, and more. See modern equivalents for historical measures. Private, no account.", "formula": "Converts classical-era units to metric using standard metrological estimates: cubit ≈ 0.4572 m, royal cubit ≈ 0.5236 m, Greek foot ≈ 0.296 m, Roman foot ≈ 0.2963 m, stadium ≈ 185 m, Roman mile ≈ 1,478 m, league ≈ 4,434 m.", "example": "One Roman mile ≈ 1,478 m ≈ 0.92 modern miles. One Greek stadium ≈ 185 m — the origin of 'stadium'.", "assumptions": [ "The standard academic estimates for each unit are used.", "Greek and Roman variants are distinguished where they differ.", "Results are historical approximations." ], "sources": [ { "organization": "Wikipedia", "title": "Cubit", "url": "https://en.wikipedia.org/wiki/Cubit" }, { "organization": "Wikipedia", "title": "Ancient Roman units of measurement", "url": "https://en.wikipedia.org/wiki/Ancient_Roman_units_of_measurement" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a cubit?", "An ancient length based on the forearm — roughly 45.7 cm (18 inches). The royal cubit was longer, about 52.4 cm." ], [ "How long is a Roman mile?", "About 1,478 meters — 1,000 Roman paces (mille passus). That's ~0.92 modern miles." ], [ "What is a stadium?", "A Greek/Roman distance of about 185 m — the length of a running track, and the origin of the word 'stadium'." ], [ "How accurate are these conversions?", "They're the best scholarly estimates from artifacts and texts, but ancient units varied by region and era — treat them as approximate." ], [ "What is a league?", "About 3 Roman miles, roughly 4,434 m — a distance one could walk in an hour." ], [ "How do I convert ancient to modern units?", "Use the converter: each ancient unit maps to a metric value (cubit → 0.4572 m, Roman mile → 1,478 m)." ], [ "Why did ancient units vary?", "They were based on body measurements and local standards — no central authority standardized them across regions." ] ] }, { "slug": "angle-converter", "name": "Angle Converter", "canonical_url": "https://boringtoolskit.com/angle-converter/", "category": "Converters", "description": "Angle converter: degrees, radians, and gradians.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "angular-momentum-calculator", "name": "Angular Momentum Calculator", "canonical_url": "https://boringtoolskit.com/angular-momentum-calculator/", "category": "Physics", "description": "Calculate angular momentum of a point mass from mass, velocity, and radius (L = mvr).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/momentum-calculator/", "/kinetic-energy-calculator/", "/force-calculator/" ], "answer": "Calculate angular momentum of a point mass from mass, velocity, and radius (L = mvr).", "formula": "Angular momentum (L) = mass × velocity × radius. Units: kg · m²/s.", "example": "A 3 kg object at 4 m/s on a radius of 2 m: L = 3 × 4 × 2 = 24 kg·m²/s.", "assumptions": [ "Mass, velocity, and radius are all in SI units (kg, m/s, m).", "The object moves perpendicular to the radius.", "Positive values are required for all three inputs." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "annuity-calculator", "name": "Annuity Calculator", "canonical_url": "https://boringtoolskit.com/annuity-calculator/", "category": "Everyday Calculators", "description": "Estimate the future value or payout of an annuity based on deposit, rate, and term.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/compound-interest/", "/investment-return-calculator/", "/retirement-planning-calculator/" ], "answer": "Estimate the future value or payout of an annuity based on deposit, rate, and term.", "formula": "Future value of an annuity = payment × [((1 + r)^n − 1) ÷ r], where r is the per-period rate and n is the number of periods, for an ordinary annuity (payments at end of period). The tool supports future-value and present-value modes.", "example": "An annuity with a $500 monthly payment earning 6% annually (0.5% monthly) over 20 years (240 periods): future value ≈ $500 × [((1.005)^240 − 1) ÷ 0.005] ≈ $500 × 462.04 ≈ $231,020.", "assumptions": [ "Payments are made at the end of each period (ordinary annuity).", "A single constant per-period rate is assumed.", "Fees, taxes, and surrender charges are not included." ], "sources": [ { "organization": "Investopedia", "title": "Annuity", "url": "https://www.investopedia.com/terms/a/annuity.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is an annuity?", "A series of equal payments made at regular intervals. It's the underlying math of pensions, retirement payouts, and fixed contribution plans." ], [ "How do I calculate future value?", "FV = payment × [((1 + r)^n − 1) ÷ r], where r is the per-period rate and n is the number of periods." ], [ "What is the difference between future and present value?", "Future value is what the payment stream grows to; present value is what that stream is worth today at a given discount rate." ], [ "Are annuities a good investment?", "It depends. The headline rate can look good, but fees, surrender charges, and lower liquidity often make a low-cost index portfolio a better choice. Compare the total cost carefully." ], [ "What rate should I use?", "Use a realistic expected return. For the per-period rate, divide the annual rate by the number of periods per year (e.g. 6% ÷ 12 = 0.5% monthly)." ], [ "Does this include fees?", "No. An annuity's real return is reduced by fees and charges, so the calculator overstates what you'd actually keep." ], [ "What is an ordinary annuity vs annuity-due?", "An ordinary annuity pays at the end of each period; annuity-due pays at the start. Annuity-due has a slightly higher value because payments earn interest sooner." ] ] }, { "slug": "annuity-payout-calculator", "name": "Annuity Payout Calculator", "canonical_url": "https://boringtoolskit.com/annuity-payout-calculator/", "category": "Finance & Investing", "description": "Annuity payout calculator: monthly income from a lump sum at a fixed rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "appliance-energy-cost-calculator", "name": "Appliance Energy Cost Calculator", "canonical_url": "https://boringtoolskit.com/appliance-energy-cost-calculator/", "category": "Energy & Electrical", "description": "Appliance energy cost calculator: running cost from wattage, usage, and your electricity rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "apr-effective-interest-calculator", "name": "APR & Effective Interest Calculator", "canonical_url": "https://boringtoolskit.com/apr-effective-interest-calculator/", "category": "Finance & Investing", "description": "Estimate payment, fee-adjusted APR, effective annual rate, and total finance cost.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/amortization-calculator/", "/emi-calculator/", "/apy-calculator/" ], "answer": "Estimate payment, fee-adjusted APR, effective annual rate, and total finance cost.", "formula": "APR = the rate that makes the loan's present value (principal minus fees) equal to the payment stream. Effective rate = (1 + APR ÷ 12)^12 − 1 for monthly compounding. Fees raise the APR above the stated rate.", "example": "A $10,000 loan at 6% for 36 months with $500 in fees: the APR is higher than 6% because you receive $9,500 but repay a 6% amortization schedule.", "assumptions": [ "The loan is amortized monthly.", "Fees are deducted from the loan proceeds.", "The loan runs to full term." ], "sources": [ { "organization": "Wikipedia", "title": "Annual percentage rate", "url": "https://en.wikipedia.org/wiki/Annual_percentage_rate" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is APR?", "The annual percentage rate — the true yearly cost of a loan including fees, expressed as a rate. It's the number to use when comparing loans." ], [ "Why is APR higher than the stated rate?", "Fees are added to the cost but you receive less money, so the effective rate rises. The APR captures that." ], [ "What is the effective annual rate?", "The EAR converts a nominal rate with monthly compounding into the equivalent yearly rate: (1 + r/12)^12 − 1." ], [ "How do I compare loans?", "Use the same amount and term, include each lender's fees, and compare the APRs — not the headline rates." ], [ "Do APRs include everything?", "No — late fees, prepayment penalties, and some charges are excluded by regulation. Read the loan terms." ], [ "What if I pay off early?", "APR assumes you hold the loan to term. Paying early changes the real cost — refinance break-even math applies." ], [ "What's the difference between APR and APY?", "APR is a borrowing cost; APY is a deposit yield. Both annualize, but APY includes compounding effects." ], [ "What is the difference between APR and interest rate?", "APR includes fees and points; the interest rate is just the borrowing cost on the principal." ], [ "How do I calculate APR?", "APR is the rate that makes the payments equal to the loan amount minus fees over the term." ], [ "Does compounding affect APR?", "Yes — more frequent compounding raises the effective annual rate above the nominal APR." ], [ "Why do lenders quote APR?", "Truth-in-Lending requires it so borrowers can compare loans with different fees." ] ] }, { "slug": "apy-calculator", "name": "APY Calculator", "canonical_url": "https://boringtoolskit.com/apy-calculator/", "category": "Finance & Investing", "description": "Convert a nominal annual interest rate and compounding frequency into annual percentage yield.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/savings-goal-calculator/", "/savings-calc/", "/compound-interest/" ], "answer": "Convert a nominal annual interest rate and compounding frequency into annual percentage yield.", "formula": "APY = (1 + nominal rate ÷ compounds per year)^(compounds per year) − 1.", "example": "", "assumptions": [ "The nominal rate and compounding frequency remain constant for one year.", "No deposits, withdrawals, taxes, or fees occur during the example.", "The result is mathematical and not a quoted bank offer." ], "sources": [ { "organization": "CFPB", "title": "Annual percentage yield definition", "url": "https://www.consumerfinance.gov/ask-cfpb/what-is-an-annual-percentage-yield-apy-en-1001/" }, { "organization": "FDIC", "title": "Deposit account information", "url": "https://www.fdic.gov/resources/deposit-insurance/" } ], "faqs": [ [ "What does APY mean and how is it calculated?", "APY, or annual percentage yield, is the real rate of return on a deposit over one year when compounding is included. This calculator converts a nominal annual rate and chosen compounding frequency into APY using APY = (1 + nominal rate ÷ compounds per year)^(compounds per year) − 1." ], [ "What is the difference between APY and APR?", "APR (annual percentage rate) states the nominal rate without compounding, while APY includes the effect of compounding. The more frequently interest compounds, the more APY exceeds the nominal rate. This calculator returns APY, so you can compare offers on an equal footing." ], [ "Does this APY estimate include bank fees or taxes?", "No. The estimate assumes no deposits, withdrawals, taxes, or fees during the year and that the rate and compounding frequency stay constant. It is a mathematical APY, not a quoted bank offer, so confirm current terms with the institution." ] ] }, { "slug": "aquarium-stocking-calculator", "name": "Aquarium Stocking Calculator", "canonical_url": "https://boringtoolskit.com/aquarium-stocking-calculator/", "category": "Pets", "description": "Aquarium stocking calculator: fish capacity by tank size.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "arc-length-calculator", "name": "Arc Length Calculator", "canonical_url": "https://boringtoolskit.com/arc-length-calculator/", "category": "Everyday Calculators", "description": "Arc length calculator: distance along a circle arc.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "area-converter", "name": "Area Converter", "canonical_url": "https://boringtoolskit.com/area-converter/", "category": "Converters", "description": "Area converter: square feet, acres, hectares, and square meters.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "area-perimeter-calculator", "name": "Area Perimeter Calculator", "canonical_url": "https://boringtoolskit.com/area-perimeter-calculator/", "category": "Everyday Calculators", "description": "Area and perimeter calculator: rectangle, triangle, circle.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-27", "related_urls": [], "answer": "Area and perimeter calculator: rectangle, triangle, circle.", "formula": "Area and perimeter depend on the shape: e.g. rectangle area = length × width, perimeter = 2 × (length + width).", "example": "A 4 m × 6 m rectangle has area 24 m² and perimeter 20 m.", "assumptions": [ "Standard geometric or arithmetic definitions apply.", "Inputs use the units you choose.", "Results are estimates, not professional advice." ], "sources": [ { "organization": "Standard mathematics definitions", "title": "Arithmetic and geometry formulas", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "arithmetic-sequence-calculator", "name": "Arithmetic Sequence Calculator", "canonical_url": "https://boringtoolskit.com/arithmetic-sequence-calculator/", "category": "School & Education", "description": "Arithmetic sequence calculator: nth term and sum from first term and common difference.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "ascii-converter", "name": "ASCII Converter", "canonical_url": "https://boringtoolskit.com/ascii-converter/", "category": "Converters", "description": "ASCII converter: characters to ASCII codes and back.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "aspect-ratio-calculator", "name": "Aspect Ratio Calculator", "canonical_url": "https://boringtoolskit.com/aspect-ratio-calculator/", "category": "Everyday Calculators", "description": "Calculate the aspect ratio from width and height, or the missing dimension to hit a target ratio like 16:9.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/image-resize/", "/pdf-to-jpg/", "/percentage-calc/" ], "answer": "Calculate the aspect ratio from width and height, or the missing dimension to hit a target ratio like 16:9.", "formula": "Aspect ratio = width ÷ height reduced to the smallest whole-number ratio using the greatest common divisor (gcd). The tool also reports the decimal value.", "example": "1920×1080 divides by gcd 120 → 16:9, the standard widescreen ratio.", "assumptions": [ "Width and height are positive numbers.", "The gcd reduction produces the standard form.", "The decimal value reflects the exact proportion." ], "sources": [ { "organization": "Wikipedia", "title": "Aspect ratio (image)", "url": "https://en.wikipedia.org/wiki/Aspect_ratio_(image)" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is an aspect ratio?", "The proportional relationship between width and height: 1920×1080 reduced to 16:9 means 16 units wide for every 9 tall." ], [ "How do I calculate it?", "Divide both dimensions by their greatest common divisor. 1920÷120 = 16, 1080÷120 = 9 → 16:9." ], [ "What is 16:9 used for?", "Standard widescreen — TVs, YouTube, most video. 9:16 is vertical video (TikTok, Shorts); 1:1 is square (Instagram)." ], [ "What's the difference between ratio and resolution?", "Ratio is the shape; resolution is the pixel count. 320×180 and 1920×1080 are both 16:9 at different resolutions." ], [ "How do I scale while keeping the ratio?", "Multiply both dimensions by the same factor — or in the resizer, use the 'inside' fit which preserves the ratio." ], [ "What is a non-integer ratio?", "Some formats use ratios like 1.91:1 (Facebook feed) that don't reduce to small whole numbers — the decimal value shows it." ], [ "Does orientation matter?", "Yes — 16:9 is landscape, 9:16 is portrait. Rotating swaps the sides." ] ] }, { "slug": "asphalt-calculator", "name": "Asphalt Calculator", "canonical_url": "https://boringtoolskit.com/asphalt-calculator/", "category": "Construction & Measurement", "description": "Estimate asphalt volume, weight, waste, and material cost for a rectangular paving area.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/gravel-calculator/", "/concrete-calculator/", "/square-feet-to-linear-feet/" ], "answer": "Estimate asphalt volume, weight, waste, and material cost for a rectangular paving area.", "formula": "Tons = length × width × compacted depth in feet × density ÷ 2,000 × (1 + waste).", "example": "", "assumptions": [ "Dimensions describe a rectangular area with uniform compacted thickness.", "145 lb/ft³ is only a starting density and is editable.", "Base aggregate, tack coat, labor, delivery, and equipment are excluded." ], "sources": [ { "organization": "FHWA", "title": "Asphalt pavement resources", "url": "https://www.fhwa.dot.gov/pavement/asphalt/" }, { "organization": "NIST", "title": "SI units and conversions", "url": "https://www.nist.gov/pml/owm/metric-si/si-units" } ], "faqs": [ [ "How does the asphalt calculator work?", "The asphalt calculator runs entirely in your browser — it takes your project dimensions (length, width, thickness) and estimates the tons of asphalt needed using standard density values. No data is sent to a server, and no account or signup is required." ], [ "Do I need to create an account to use the asphalt calculator?", "No. The asphalt calculator is a no-signup, browser-based tool. Everything is processed locally on your device, so your measurements and results stay private and are never stored or shared." ], [ "Is the asphalt calculator free to use?", "Yes. The asphalt calculator is completely free with no hidden fees, no sign-up required, and no signup and no uploads. You can use it as many times as you need directly in your browser." ] ] }, { "slug": "atmospheric-pressure-calculator", "name": "Atmospheric Pressure Calculator", "canonical_url": "https://boringtoolskit.com/atmospheric-pressure-calculator/", "category": "Geography", "description": "Atmospheric pressure calculator: barometric pressure at elevation (US standard atmosphere).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "attendance-calculator", "name": "Attendance Calculator", "canonical_url": "https://boringtoolskit.com/attendance-calculator/", "category": "School & Education", "description": "Attendance calculator: attendance percentage and days you can still miss to stay above a threshold.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "audio-time-stretch-calculator", "name": "Audio Time Stretch Calculator", "canonical_url": "https://boringtoolskit.com/audio-time-stretch-calculator/", "category": "Music & Audio", "description": "Calculate the new duration when audio playback speed changes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/bpm-to-ms-calculator/", "/metronome-bpm-calculator/", "/vinyl-rpm-calculator/" ], "answer": "Calculate the new duration when audio playback speed changes.", "formula": "New duration = original ÷ playback speed. Time change % = (1 ÷ speed − 1) × 100.", "example": "A 120 second audio at 0.75× speed: new duration = 120 ÷ 0.75 = 160 s, a 33.3% increase. At 1.25× it is 96 s, a 20% decrease.", "assumptions": [ "Original duration is in seconds and speed must be positive.", "Time-stretching changes duration without changing pitch (by design).", "The result is a timing estimate, not an encoding guarantee." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "auto-insurance-by-state-calculator", "name": "Auto Insurance by State", "canonical_url": "https://boringtoolskit.com/auto-insurance-by-state-calculator/", "category": "Vehicles", "description": "Auto insurance by state: minimum liability limits, no-fault status and coverage tips for every state.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "auto-loan-calculator", "name": "Auto Loan Calculator", "canonical_url": "https://boringtoolskit.com/auto-loan-calculator/", "category": "Finance & Investing", "description": "Estimate an auto loan payment, amount financed, total interest, and year-by-year balance.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/loan-comparison-calculator/", "/loan-to-value-calculator/", "/amortization-calculator/" ], "answer": "Estimate an auto loan payment, amount financed, total interest, and year-by-year balance.", "formula": "Auto loan payment = principal × [r × (1+r)^n] ÷ [(1+r)^n − 1], where r = annual rate ÷ 12 and n = term in months. Then total interest and the full amortization schedule are computed over the loan.", "example": "a $25,000 auto loan at 6% for 60 months pays about $483/month and accrues roughly $4,000 in total interest.", "assumptions": [ "A fixed-rate amortizing auto loan.", "Sales tax and fees are separate, entered only if you add them.", "The payment is principal + interest only, before taxes and registration." ], "sources": [ { "organization": "Investopedia", "title": "Auto Loan", "url": "https://www.investopedia.com/terms/a/auto-loan.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate an auto loan payment?", "Payment = P × [r(1+r)^n] ÷ [(1+r)^n − 1], where r is the monthly rate and n the number of months." ], [ "What is a good auto loan term?", "Shorter is usually cheaper. 36–60 months is common; terms over 72 months add a lot of interest and increase the risk of owing more than the car's worth." ], [ "Should I put money down?", "A bigger down payment reduces the amount financed and the interest, and lowers the chance of being upside-down. It also can improve your rate." ], [ "Does the payment include tax and fees?", "Not by default. Sales tax, title, and registration are separate. Factor them into the total amount you finance." ], [ "How much interest will I pay?", "It depends on the rate, term, and amount. A 6% 60-month loan costs roughly $4,000 in interest per $25,000 borrowed." ], [ "What rate will I get?", "Your rate depends on credit score, lender, and the car. Check pre-approval rates before shopping to know your number." ], [ "Why might I owe more than the car is worth?", "Because cars depreciate faster than a long loan pays down. A long term with little down payment can leave you 'upside-down' early in the loan." ] ] }, { "slug": "average-atomic-mass-calculator", "name": "Average Atomic Mass Calculator", "canonical_url": "https://boringtoolskit.com/average-atomic-mass-calculator/", "category": "Chemistry", "description": "Calculate average atomic mass from isotope masses and abundances.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/molar-mass-calculator/", "/electron-configuration-calculator/", "/empirical-formula-calculator/" ], "answer": "Calculate average atomic mass from isotope masses and abundances.", "formula": "Average atomic mass = Σ (isotope mass × relative abundance), with abundances normalized to the fraction version.", "example": "For 35 amu at 75% and 37 amu at 25%: 35 × 0.75 + 37 × 0.25 = 26.25 + 9.25 = 35.50 amu.", "assumptions": [ "Each isotope is entered as mass and abundance (percent or fraction).", "Abundances are normalized to a fraction before computing the weighted average.", "The sum of abundances should equal the total; unmatched entries are flagged." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "average-return-calculator", "name": "Average Return Calculator", "canonical_url": "https://boringtoolskit.com/average-return-calculator/", "category": "Statistics", "description": "Average return calculator: simple average of yearly returns.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "baby-formula-calculator", "name": "Baby Formula Calculator", "canonical_url": "https://boringtoolskit.com/baby-formula-calculator/", "category": "Health", "description": "Baby formula calculator: ounces per feeding from baby weight.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "background-text-color-calculator", "name": "Background Text Color Calculator", "canonical_url": "https://boringtoolskit.com/background-text-color-calculator/", "category": "Colors & Design", "description": "Background text color calculator: choose black or white text on any background color for best contrast.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "backsplash-calculator", "name": "Backsplash Calculator", "canonical_url": "https://boringtoolskit.com/backsplash-calculator/", "category": "Construction & Measurement", "description": "Backsplash calculator: material area for a kitchen backsplash after subtracting openings.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "baking-conversions", "name": "Baking Conversions", "canonical_url": "https://boringtoolskit.com/baking-conversions/", "category": "Converters", "description": "Convert cooking and baking measurements between cups, tablespoons, teaspoons, grams, ounces, milliliters, and liters, with ingredient densities.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "August 2026", "related_urls": [ "/currency-conv/", "/sales-tax-vat-calculator/", "/percentage-calc/" ], "answer": "Convert cooking and baking measurements between cups, tablespoons, teaspoons, grams, ounces, milliliters, and liters, with ingredient densities.", "formula": "To convert within volume (cups, tbsp, tsp, ml, l), multiply by the US ml equivalents. Within mass (g, oz, lb), multiply by the gram equivalents. For mass↔volume, convert using ingredient density in grams per US cup.", "example": "1 US cup of all-purpose flour ≈ 120 grams. 1 US cup = 16 tablespoons.", "assumptions": [ "US customary cup/tablespoon/teaspoon are used.", "Ingredient densities (g/cup) are typical values, not brand-specific.", "Conversions are planning estimates for home cooking." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculation methodology and verification standard", "url": "/methodology/" } ], "faqs": [ [ "How do you convert cups to grams for baking?", "Multiply the volume by the ingredient’s density in grams per cup. Flour is about 120 g/cup, sugar about 200 g/cup, and butter about 227 g/cup." ], [ "Why does the cup-to-gram conversion depend on the ingredient?", "A cup is a volume measure, while grams measure mass. Different ingredients have different densities, so the same cup of flour and sugar weigh different amounts." ], [ "What US standard volume does this calculator use?", "One US cup = 236.59 ml = 16 tablespoons = 48 teaspoons. Butter and oil are weighted by their standard densities." ] ] }, { "slug": "baking-ratio-calculator", "name": "Baking Ratio Calculator", "canonical_url": "https://boringtoolskit.com/baking-ratio-calculator/", "category": "Food & Cooking", "description": "Baking ratio calculator: scale ingredients by baker's percentage or classic ratios (e.g., 3:2:1 pastry).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "balance-transfer-savings-calculator", "name": "Balance Transfer Savings Calculator", "canonical_url": "https://boringtoolskit.com/balance-transfer-savings-calculator/", "category": "Finance & Investing", "description": "Compare keeping credit-card debt with transferring it to a promotional APR after fees.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/credit-card-payoff-calculator/", "/compound-interest/", "/apr-effective-interest-calculator/" ], "answer": "Compare keeping credit-card debt with transferring it to a promotional APR after fees.", "formula": "Simulates paying off a balance at the current APR vs a 0% (or low) promotional rate: interest paid in each scenario; savings = interest at current APR − interest at promo rate, minus the transfer fee.", "example": "A $5,000 balance at 22% APR paid at $400/month costs roughly $700 in interest over 12 months; a 0% transfer for 12 months with a 3% fee ($150) saves most of that.", "assumptions": [ "Payments are made monthly at the entered amount.", "No new purchases are added to the card.", "The promo rate applies for the full stated period." ], "sources": [ { "organization": "Wikipedia", "title": "Balance transfer", "url": "https://en.wikipedia.org/wiki/Balance_transfer" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How much can a balance transfer save?", "The interest difference between your current APR and the promo rate, minus the transfer fee. The tool computes it exactly." ], [ "What is a balance transfer fee?", "A charge to move the balance — usually 3–5% of the amount. $5,000 at 3% costs $150." ], [ "What happens when the promo ends?", "The remaining balance reverts to the standard APR — which is why paying off before the deadline is critical." ], [ "Is a 0% transfer always worth it?", "Only if the fee plus any remaining interest is less than the interest you'd otherwise pay. Run the numbers." ], [ "Does the promo apply to new purchases?", "Usually not — new purchases typically carry the standard APR." ], [ "How should I pay it off?", "Set a monthly payment that clears the balance before the promo ends, and don't add new debt to the card." ], [ "Does transferring hurt my credit?", "A hard inquiry and the new account can temporarily lower your score; utilization changes can help or hurt." ] ] }, { "slug": "balloon-payment-calculator", "name": "Balloon Payment Calculator", "canonical_url": "https://boringtoolskit.com/balloon-payment-calculator/", "category": "Finance & Investing", "description": "Balloon payment calculator: monthly payment plus final balloon balance.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "baluster-spacing-calculator", "name": "Baluster Spacing Calculator", "canonical_url": "https://boringtoolskit.com/baluster-spacing-calculator/", "category": "Construction & Measurement", "description": "Baluster spacing calculator: even spacing for railing balusters.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "bandwidth-calculator", "name": "Bandwidth Calculator", "canonical_url": "https://boringtoolskit.com/bandwidth-calculator/", "category": "Time & Work", "description": "Bandwidth calculator: transfer time for a file size at a given connection speed.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "base64-tool", "name": "Base64 Encoder Decoder", "canonical_url": "https://boringtoolskit.com/base64-tool/", "category": "Converters", "description": "Encode and decode Base64 text, with local previews for PNG, JPEG, GIF, and WebP image data.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/csv-to-json/", "/qr-generator/", "/pdf-to-jpg/" ], "answer": "Encode and decode Base64 text, with local previews for PNG, JPEG, GIF, and WebP image data.", "formula": "Encoding: each 3 bytes of input become 4 base64 characters (6 bits each) from the A–Za–z0–9+/ alphabet, padded with '=' to a multiple of 4. Decoding reverses the process.", "example": "'Hi' encodes to 'SGk='. Decoding 'SGk=' returns 'Hi'.", "assumptions": [ "Standard base64 alphabet and padding are used.", "The input is valid base64 when decoding.", "File handling is supported by the browser." ], "sources": [ { "organization": "Wikipedia", "title": "Base64", "url": "https://en.wikipedia.org/wiki/Base64" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is base64?", "An encoding that turns binary data into ASCII text using 64 characters, so it can travel through text-only channels (email, JSON, URLs)." ], [ "How do I encode text?", "Paste it and choose encode. 'Hi' becomes 'SGk='." ], [ "Is base64 encryption?", "No — it's a reversible encoding. Anyone can decode it, so never use it for secrets." ], [ "Why is base64 bigger than the original?", "It uses 4 characters per 3 bytes — about 33% overhead." ], [ "What is the '=' padding for?", "It pads the output to a multiple of 4 characters when the input isn't a multiple of 3 bytes." ], [ "Can I encode images?", "Yes — drop a file to get its data URI (useful for inline images in HTML)." ], [ "What is URL-safe base64?", "A variant that swaps + and / for - and _ so the output works in URLs without escaping." ] ] }, { "slug": "baseball-ops-calculator", "name": "Baseball OPS Calculator", "canonical_url": "https://boringtoolskit.com/baseball-ops-calculator/", "category": "Sports", "description": "Baseball OPS calculator: on-base percentage plus slugging percentage.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "baseboard-calculator", "name": "Baseboard Calculator", "canonical_url": "https://boringtoolskit.com/baseboard-calculator/", "category": "Construction & Measurement", "description": "Baseboard calculator: linear feet and boards for a room.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "battery-bank-calculator", "name": "Battery Bank Calculator", "canonical_url": "https://boringtoolskit.com/battery-bank-calculator/", "category": "Energy & Electrical", "description": "Battery bank calculator: amp-hours for an off-grid system.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "battery-life-calculator", "name": "Battery Life Calculator", "canonical_url": "https://boringtoolskit.com/battery-life-calculator/", "category": "Energy & Electrical", "description": "Battery life calculator: runtime from battery capacity, voltage, and load power.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "battery-runtime-calculator", "name": "Battery Runtime Calculator", "canonical_url": "https://boringtoolskit.com/battery-runtime-calculator/", "category": "Energy & Electrical", "description": "Estimate ideal and adjusted battery runtime from capacity, voltage, load, efficiency, and usable depth.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/watts-to-amps-calculator/", "/electricity-cost-calculator/", "/ev-charging-cost-calculator/" ], "answer": "Estimate ideal and adjusted battery runtime from capacity, voltage, load, efficiency, and usable depth.", "formula": "Nominal energy (Wh) = amp-hours × volts; runtime = nominal energy × usable fraction × efficiency ÷ load watts.", "example": "", "assumptions": [ "Voltage and load remain constant.", "Efficiency and usable capacity are user-entered aggregate factors.", "Peukert effects, temperature, degradation, surge loads, and reserve margins are excluded." ], "sources": [ { "organization": "U.S. Department of Energy", "title": "Energy storage basics", "url": "https://www.energy.gov/oe/energy-storage" }, { "organization": "Sandia National Laboratories", "title": "Energy storage systems", "url": "https://www.sandia.gov/ess-ssl/" } ], "faqs": [] }, { "slug": "batting-average-calculator", "name": "Batting Average Calculator", "canonical_url": "https://boringtoolskit.com/batting-average-calculator/", "category": "Sports", "description": "Batting average calculator: hits divided by at-bats.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "bayes-theorem-calculator", "name": "Bayes Theorem Calculator", "canonical_url": "https://boringtoolskit.com/bayes-theorem-calculator/", "category": "Statistics", "description": "Bayes theorem calculator: posterior probability P(A|B) from prior and likelihood rates.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "beam-load-calculator", "name": "Beam Load Calculator", "canonical_url": "https://boringtoolskit.com/beam-load-calculator/", "category": "Construction & Measurement", "description": "Beam load calculator: max deflection of a uniformly loaded simple beam (simplified).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "bearing-calculator", "name": "Bearing Calculator", "canonical_url": "https://boringtoolskit.com/bearing-calculator/", "category": "Geography", "description": "Bearing calculator: initial compass bearing between two coordinates.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "beer-abv-calculator", "name": "Beer ABV Calculator", "canonical_url": "https://boringtoolskit.com/beer-abv-calculator/", "category": "Food & Cooking", "description": "Beer ABV calculator: alcohol by volume from original and final gravity.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "belt-size-calculator", "name": "Belt Size Calculator", "canonical_url": "https://boringtoolskit.com/belt-size-calculator/", "category": "Converters", "description": "Belt size calculator: belt length from waist size.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "betting-odds-converter", "name": "Betting Odds Converter", "canonical_url": "https://boringtoolskit.com/betting-odds-converter/", "category": "Gaming", "description": "Betting odds converter: American, decimal, and fractional odds with implied probability.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "big-number-calculator", "name": "Big Number Calculator", "canonical_url": "https://boringtoolskit.com/big-number-calculator/", "category": "Everyday Calculators", "description": "Big number calculator: exact arithmetic on numbers up to 10^30.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-27", "related_urls": [], "answer": "Big number calculator: exact arithmetic on numbers up to 10^30.", "formula": "Arithmetic on large integers with precision beyond normal floating-point display limits.", "example": "1,234,567,890 × 98,765,432,101 stays exact rather than rounding.", "assumptions": [ "Standard geometric or arithmetic definitions apply.", "Inputs use the units you choose.", "Results are estimates, not professional advice." ], "sources": [ { "organization": "Standard mathematics definitions", "title": "Arithmetic and geometry formulas", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "billing-rate-calculator", "name": "Billing Rate Calculator", "canonical_url": "https://boringtoolskit.com/billing-rate-calculator/", "category": "Time & Work", "description": "Billing rate calculator: hourly freelance rate from salary.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "binary-calculator", "name": "Binary Calculator", "canonical_url": "https://boringtoolskit.com/binary-calculator/", "category": "School & Education", "description": "Binary calculator: add, subtract, multiply, and divide binary numbers with decimal results.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "binomial-probability-calculator", "name": "Binomial Probability Calculator", "canonical_url": "https://boringtoolskit.com/binomial-probability-calculator/", "category": "Statistics", "description": "Binomial probability calculator: exact and cumulative probabilities for k successes in n trials.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "biorhythm-calculator", "name": "Biorhythm Calculator", "canonical_url": "https://boringtoolskit.com/biorhythm-calculator/", "category": "Astrology", "description": "Biorhythm calculator: physical, emotional, and intellectual cycles from birth date to a target date.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "blood-alcohol-content-calculator", "name": "Blood Alcohol Content Calculator", "canonical_url": "https://boringtoolskit.com/blood-alcohol-content-calculator/", "category": "Health", "description": "Blood alcohol content (BAC) calculator: Widmark estimate from drinks, weight, and time \\u2014 informational only.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "blood-pressure-calculator", "name": "Blood Pressure Category Calculator", "canonical_url": "https://boringtoolskit.com/blood-pressure-calculator/", "category": "Health", "description": "Blood pressure category calculator: classify a systolic/diastolic reading using the AHA categories.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "blood-sugar-converter", "name": "Blood Sugar Converter", "canonical_url": "https://boringtoolskit.com/blood-sugar-converter/", "category": "Health", "description": "Blood sugar converter: convert glucose between mg/dL and mmol/L instantly.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "blood-type-inheritance-calculator", "name": "Blood Type Inheritance Calculator", "canonical_url": "https://boringtoolskit.com/blood-type-inheritance-calculator/", "category": "Biology", "description": "Blood type inheritance calculator: possible ABO child blood types from two parents.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "bmi-calc", "name": "BMI Calculator", "canonical_url": "https://boringtoolskit.com/bmi-calc/", "category": "Health", "description": "Calculate BMI quickly and privately in your browser.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/body-fat-calculator/", "/calorie-calc/", "/ideal-weight-calculator/" ], "answer": "Calculate BMI quickly and privately in your browser.", "formula": "BMI = weight (kg) ÷ height (m)², or weight (lb) ÷ height (in)² × 703. Categories: <18.5 underweight, 18.5–24.9 healthy, 25–29.9 overweight, 30+ obese.", "example": "170 lb at 5'9\": BMI = 170 ÷ 69² × 703 = 25.1 — top of the healthy range.", "assumptions": [ "Height and weight are entered accurately.", "WHO category thresholds apply.", "The result is used as a screening tool." ], "sources": [ { "organization": "Wikipedia", "title": "Body mass index", "url": "https://en.wikipedia.org/wiki/Body_mass_index" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate BMI?", "Weight (kg) ÷ height (m)² — or lb ÷ in² × 703: 170 ÷ 69² × 703 = 25.1." ], [ "What is a healthy BMI?", "18.5–24.9; under 18.5 is underweight, 25–29.9 overweight, 30+ obese." ], [ "Is BMI accurate for athletes?", "No — it doesn't distinguish muscle from fat, so muscular people read as overweight." ], [ "Does BMI work for children?", "Yes, with age/sex percentiles — adult categories don't apply." ], [ "What's better than BMI?", "Body fat percentage, waist circumference, and waist-to-hip ratio add the missing information." ], [ "Why do thresholds differ by ethnicity?", "Some Asian populations face higher risk at lower BMI — WHO has adjusted guidance." ], [ "Is BMI a diagnosis?", "No — it's a screening number. Health assessment considers many factors." ] ] }, { "slug": "bmr-tdee-calculator", "name": "BMR & TDEE Calculator", "canonical_url": "https://boringtoolskit.com/bmr-tdee-calculator/", "category": "Health", "description": "Estimate adult BMR and TDEE from the Mifflin-St Jeor equation and an explicit activity multiplier.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/calories-burned-calculator/", "/ideal-weight-calculator/", "/bmi-calc/" ], "answer": "Estimate adult BMR and TDEE from the Mifflin-St Jeor equation and an explicit activity multiplier.", "formula": "Mifflin-St Jeor BMR: male = 10×weight(kg) + 6.25×height(cm) − 5×age + 5; female = 10×weight(kg) + 6.25×height(cm) − 5×age − 161. TDEE = BMR × activity multiplier: 1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 very active, 1.9 extra active.", "example": "A 30-year-old man, 80 kg, 180 cm: BMR = 800 + 1,125 − 150 + 5 = 1,780 kcal/day. With moderate activity (1.55), TDEE ≈ 2,759 kcal/day.", "assumptions": [ "The Mifflin-St Jeor equation applies (adults 18–100).", "The chosen activity multiplier reflects the user's lifestyle.", "Results are estimates for planning, not medical prescriptions." ], "sources": [ { "organization": "MDCalc", "title": "Mifflin-St Jeor Equation (calorie deficit)", "url": "https://www.mdcalc.com/calc/56/mifflin-st-jeor-equation-calorie-deficit" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is BMR?", "Basal metabolic rate — the calories your body burns at complete rest just to maintain life. It's typically the largest share of your daily burn." ], [ "What is TDEE?", "Total daily energy expenditure — BMR plus activity and digestion. Eating at TDEE maintains weight; below it loses, above it gains." ], [ "How is BMR calculated?", "The Mifflin-St Jeor equation: 10×weight(kg) + 6.25×height(cm) − 5×age + 5 (men) or − 161 (women)." ], [ "What activity multiplier should I pick?", "Be honest: 1.2 for desk jobs, 1.375 light exercise 1–3 days/week, 1.55 moderate 3–5 days, 1.725 very active, 1.9 extra active. Overestimating activity is common." ], [ "How many calories should I eat to lose weight?", "Start with TDEE minus 300–500 kcal/day for a sustainable ~0.5–1 lb/week loss, and adjust based on real progress." ], [ "Is this accurate?", "It's a strong population estimate, but individual results vary with muscle mass and metabolism. Track your weight for 2–4 weeks and adjust." ], [ "Do I need to recalculate?", "Yes — as your weight changes by 5–10 lb, recalculate. BMR falls as you lose weight, so targets drift." ] ] }, { "slug": "board-foot-calculator", "name": "Board Foot Calculator", "canonical_url": "https://boringtoolskit.com/board-foot-calculator/", "category": "Construction & Measurement", "description": "Calculate lumber volume in board feet from thickness, width, length, and quantity.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/square-footage-calculator/", "/decking-calculator/", "/fence-material-calculator/" ], "answer": "Calculate lumber volume in board feet from thickness, width, length, and quantity.", "formula": "Board feet = thickness (in) × width (in) × length (ft) ÷ 12. One board foot = 1 inch × 1 foot × 1 foot (144 in³).", "example": "A 1″ × 6″ × 8′ board: 1 × 6 × 8 ÷ 12 = 4 board feet.", "assumptions": [ "Nominal or actual dimensions are entered consistently.", "One board foot = 144 in³.", "Quantity multiplies the per-piece volume." ], "sources": [ { "organization": "Wikipedia", "title": "Board foot", "url": "https://en.wikipedia.org/wiki/Board_foot" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a board foot?", "A lumber volume unit: 1″ × 1′ × 1′, or 144 cubic inches. It's how hardwood is priced." ], [ "How do I calculate board feet?", "Thickness (in) × width (in) × length (ft) ÷ 12. A 1″×6″×8′ board = 1×6×8÷12 = 4 board feet." ], [ "What's the difference between nominal and actual size?", "A '2×4' is nominally 2×4 but actually 1.5×3.5 after surfacing. Use actual sizes for accurate volume." ], [ "How much lumber do I need for a project?", "Calculate each piece's board feet, sum them, and add 10–15% for waste and defects." ], [ "Is softwood priced in board feet?", "Usually not — 2× lumber is sold per linear foot; board feet is the standard for hardwood and rough lumber." ], [ "How do I price a board?", "Multiply board feet by the price per board foot (e.g., 4 bd ft × $5 = $20)." ], [ "What is the difference between board foot and square foot?", "Square feet measure area (flooring); board feet measure volume (lumber). They serve different pricing purposes." ], [ "Is lumber priced by board foot?", "Yes — standardizing price across sizes, especially for hardwoods and framing." ], [ "Should I add waste?", "10–20% for cutting and defects, depending on the project." ] ] }, { "slug": "boat-loan-calculator", "name": "Boat Loan Calculator", "canonical_url": "https://boringtoolskit.com/boat-loan-calculator/", "category": "Finance & Investing", "description": "Boat loan calculator: boat and RV loan payment.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "body-fat-calculator", "name": "Body Fat Estimate Calculator", "canonical_url": "https://boringtoolskit.com/body-fat-calculator/", "category": "Health", "description": "Estimate adult body-fat percentage with the U.S. Navy circumference method and clear limitations.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/bmi-calc/", "/calorie-calc/", "/age-calculator/" ], "answer": "Estimate adult body-fat percentage with the U.S. Navy circumference method and clear limitations.", "formula": "Male: 86.010×log10(waist−neck) − 70.041×log10(height) + 36.76. Female: 163.205×log10(waist+hip−neck) − 97.684×log10(height) − 78.387. Measurements in inches.", "example": "", "assumptions": [ "The named U.S. Navy circumference equations are used with inch measurements.", "Measurements must follow a consistent tape-placement protocol.", "The estimate is not a clinical diagnosis and may be inaccurate for individuals outside the source population." ], "sources": [ { "organization": "U.S. Navy", "title": "Guide 4 Body Composition Assessment", "url": "https://www.mynavyhr.navy.mil/Portals/55/Support/Culture%20Resilience/Physical/Guide%204-%20Body%20Composition%20Assessment%20(BCA)%20(MAR%202023).pdf" }, { "organization": "CDC", "title": "About adult BMI (context and limitations of screening measures)", "url": "https://www.cdc.gov/bmi/adult-calculator/bmi-categories.html" } ], "faqs": [ [ "How does the body fat calculator work?", "It uses measurements like height, neck, waist, and hip to estimate body fat percentage with established formulas. Just enter your numbers in the browser—no signup required." ], [ "Is this body fat calculator accurate?", "It provides a close estimate using the U.S. Navy method, ideal for tracking trends over time. For precise clinical results, consult a professional." ], [ "Do I need to create an account to use it?", "No, the body fat calculator is completely free and browser-based with no signup needed. Simply open the page and input your measurements." ] ] }, { "slug": "body-surface-area-calculator", "name": "Body Surface Area Calculator", "canonical_url": "https://boringtoolskit.com/body-surface-area-calculator/", "category": "Health", "description": "Body surface area calculator: Mosteller formula from height and weight.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "bond-calculator", "name": "Bond Calculator", "canonical_url": "https://boringtoolskit.com/bond-calculator/", "category": "Everyday Calculators", "description": "Estimate a bond's current yield and price from coupon rate, face value, and market rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/compound-interest/", "/present-value-calculator/", "/cd-calculator/" ], "answer": "Estimate a bond's current yield and price from coupon rate, face value, and market rate.", "formula": "Bond price = Σ (annual coupon ÷ (1 + market rate)^t) for each year t, plus face value ÷ (1 + market rate)^years. The annual coupon is the face value × coupon rate; current yield = annual coupon ÷ price.", "example": "A $1,000 bond with a 5% coupon ($50/year) and 10 years to maturity priced at a 6% market rate: price ≈ $50/1.06 + … + $50/1.06^10 + $1,000/1.06^10 ≈ $926.40, a $73.60 discount from face.", "assumptions": [ "Coupons are paid annually.", "A single flat market rate is used for discounting.", "Credit risk, taxes, and call features are not modeled." ], "sources": [ { "organization": "Investopedia", "title": "Bond", "url": "https://www.investopedia.com/terms/b/bond.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a bond?", "A bond is a debt instrument: you lend money to an issuer (government or corporation) in exchange for regular coupon payments and the return of the face value at maturity." ], [ "Why does the price change when rates change?", "Bond price and market rates move inversely. When new bonds pay higher rates, existing bonds must fall in price to offer a comparable yield." ], [ "What is current yield?", "Current yield = annual coupon ÷ price. It measures the income return at the price you pay, which differs from the coupon rate when the bond trades at a premium or discount." ], [ "What does trading at a premium or discount mean?", "A bond above face value trades at a premium; below face, at a discount. A discount usually means market rates rose after issuance; a premium means they fell." ], [ "What is yield to maturity?", "YTM is the total return if you hold the bond to maturity, including all coupons and the gain or loss from price to face value. It is the more complete yield measure than current yield." ], [ "Are bonds risk-free?", "No. Government bonds carry low credit risk, but corporate bonds can default, and all bonds carry interest-rate risk: selling before maturity can mean a loss." ], [ "Does this calculator include taxes?", "No. It prices the bond's cash flows before tax. After-tax return depends on your tax rate and the bond's tax treatment." ] ] }, { "slug": "bonus-percentage-calculator", "name": "Bonus Percentage Calculator", "canonical_url": "https://boringtoolskit.com/bonus-percentage-calculator/", "category": "Time & Work", "description": "Bonus percentage calculator: bonus from salary and percent.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "bowling-handicap-calculator", "name": "Bowling Handicap Calculator", "canonical_url": "https://boringtoolskit.com/bowling-handicap-calculator/", "category": "Sports", "description": "Bowling handicap calculator: league handicap from average.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "bpm-to-delay-calculator", "name": "BPM to Delay Time Calculator", "canonical_url": "https://boringtoolskit.com/bpm-to-delay-calculator/", "category": "Everyday Calculators", "description": "Convert BPM (beats per minute) into delay and reverb timing in milliseconds for quarter, eighth, and dotted eighth notes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/metronome-bpm-calculator/", "/bpm-to-ms-calculator/", "/time-card-calculator/" ], "answer": "Convert BPM (beats per minute) into delay and reverb timing in milliseconds for quarter, eighth, and dotted eighth notes.", "formula": "Delay time = 60,000 ÷ BPM per beat. Note values divide that: quarter = 1 beat, eighth = ½, dotted eighth = ¾, sixteenth = ¼, triplet = ⅓.", "example": "At 120 BPM, a quarter-note delay is 500 ms; eighth notes are 250 ms.", "assumptions": [ "The BPM is accurate for the song.", "Standard note divisions apply.", "The delay is set in milliseconds." ], "sources": [ { "organization": "Wikipedia", "title": "Tempo", "url": "https://en.wikipedia.org/wiki/Tempo" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate delay time from BPM?", "60,000 ÷ BPM: 120 BPM → 500 ms per quarter note." ], [ "What is the formula?", "Milliseconds per beat = 60,000 ÷ BPM. Eighth = half, sixteenth = quarter, triplet = third." ], [ "What BPM is typical?", "Pop/rock runs 90–140 BPM; hip-hop 70–100; the tool works for any." ], [ "What is a dotted eighth?", "¾ of a beat — the classic rhythmic delay setting (e.g., 375 ms at 120 BPM)." ], [ "How do I find the BPM of a song?", "Tap along or use a DAW/phone app; the metronome tool can help set it." ], [ "Do I use quarter or dotted eighth?", "Musical preference — quarters give a steady echo, dotted eighths a syncopated one." ], [ "Can I convert ms back to BPM?", "Yes — BPM = 60,000 ÷ ms per beat." ], [ "How do I calculate delay time?", "60,000 ÷ BPM for a quarter note; divide by 2 for eighths." ], [ "What is the dotted eighth formula?", "60,000 ÷ BPM × 0.75 — the classic rhythmic delay." ], [ "Why does delay time matter?", "Tempo-locked delays sit in the groove; off-time delays muddy it." ], [ "Do I need different times for different notes?", "Yes — quarters, eighths, dotted eighths, and triplets all have distinct values." ] ] }, { "slug": "bpm-to-ms-calculator", "name": "BPM to MS Calculator", "canonical_url": "https://boringtoolskit.com/bpm-to-ms-calculator/", "category": "Music & Audio", "description": "Convert beats per minute to milliseconds for note divisions used in music production.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/metronome-bpm-calculator/", "/frequency-to-note-calculator/", "/audio-time-stretch-calculator/" ], "answer": "Convert beats per minute to milliseconds for note divisions used in music production.", "formula": "Quarter-note duration (ms) = 60,000 ÷ BPM. Eighth = quarter ÷ 2; dotted eighth = quarter × 0.75; sixteenth = quarter ÷ 4; triplet eighth = quarter ÷ 3; bar (4 beats) = quarter × 4.", "example": "At 120 BPM: quarter note = 500 ms, eighth = 250 ms, sixteenth = 125 ms, bar = 2,000 ms.", "assumptions": [ "BPM must be positive.", "Times are note durations at the given tempo, not actual audio.", "Dotted and triplet values follow the standard subdivisions." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "bra-size-calculator", "name": "Bra Size Calculator", "canonical_url": "https://boringtoolskit.com/bra-size-calculator/", "category": "Health", "description": "Bra size calculator: band and cup size from underbust and bust measurements.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "break-even-ratio-calculator", "name": "Break-Even Ratio Calculator", "canonical_url": "https://boringtoolskit.com/break-even-ratio-calculator/", "category": "Finance & Investing", "description": "Calculate the break-even ratio for a rental property. See what share of income is consumed before cash flow turns positive.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/debt-service-coverage-ratio-calculator/", "/net-operating-income-calculator/", "/loan-to-value-calculator/" ], "answer": "Calculate the break-even ratio for a rental property. See what share of income is consumed before cash flow turns positive.", "formula": "Break-even ratio = (annual debt service + annual operating expenses) ÷ annual gross income × 100. A ratio under 100% means the property's income covers its debt and operating costs, with margin left over.", "example": "With $22,000 annual debt service, $8,000 operating expenses, and $36,000 annual gross income, the break-even ratio = ($22,000 + $8,000) ÷ $36,000 = 83.3%.", "assumptions": [ "Break-even ratio uses gross income, before vacancy.", "Debt service is the full annual mortgage payment (P&I).", "Operating expenses exclude debt service and income tax." ], "sources": [ { "organization": "Investopedia", "title": "Break-Even Ratio", "url": "https://www.investopedia.com/terms/b/break-even-ratio.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a good break-even ratio?", "Most lenders want it below about 85–90%. Under 100% means income covers debt plus expenses; a lower ratio shows more cushion." ], [ "How do I calculate break-even ratio?", "(Annual debt service + annual operating expenses) ÷ annual gross income × 100." ], [ "What does a break-even ratio over 100% mean?", "The property's income is less than its debt and operating costs — it's operating at a loss before considering vacancy." ], [ "Is break-even ratio the same as DSCR?", "No. DSCR is NOI ÷ debt service (focuses on the loan cushion). Break-even ratio blends debt AND operating costs against gross income. They're complementary." ], [ "Why do lenders use this?", "It's a default-risk measure. A lower break-even ratio means more of the income is free after covering costs, so loan default is less likely." ], [ "Does it account for vacancy?", "No — it uses gross income. Stress-test by removing a vacancy allowance to see the true break-even." ], [ "What is the default ratio?", "It's another name for the break-even ratio — the debt service plus operating expenses relative to gross income." ] ] }, { "slug": "break-even-units-calculator", "name": "Break-Even Units Calculator", "canonical_url": "https://boringtoolskit.com/break-even-units-calculator/", "category": "Seller & Business", "description": "Find break-even units instantly: calculate contribution margin, required revenue, and units needed to cover costs and target profit.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/price-increase-impact-calculator/", "/cash-flow-runway-calculator/", "/customer-lifetime-value-calculator/" ], "answer": "Find break-even units instantly: calculate contribution margin, required revenue, and units needed to cover costs and target profit.", "formula": "Break-even units = fixed costs ÷ (price − variable cost per unit). With a target profit: (fixed costs + target profit) ÷ contribution margin. Contribution margin = price − variable cost.", "example": "Fixed costs of $10,000, a $50 price, and $30 variable cost: contribution = $20, so break-even = 10,000 ÷ 20 = 500 units.", "assumptions": [ "Fixed and variable costs are accurately separated.", "The unit price is constant.", "All units produced are sold at that price." ], "sources": [ { "organization": "Wikipedia", "title": "Break-even (economics)", "url": "https://en.wikipedia.org/wiki/Break-even_(economics)" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is break-even?", "The sales volume where revenue equals costs — no profit, no loss. After it, every unit sold adds profit." ], [ "How do I calculate it?", "Divide fixed costs by the contribution margin (price − variable cost). $10,000 ÷ ($50 − $30) = 500 units." ], [ "What is the contribution margin?", "Price minus variable cost — the amount each sale contributes to covering fixed costs and building profit." ], [ "How do I calculate units for a target profit?", "Add the target profit to fixed costs, then divide by the contribution margin." ], [ "What if my price is below variable cost?", "You lose money on every sale — no volume fixes that. Raise the price or cut the variable cost." ], [ "Do fixed costs stay constant?", "Only within a range — at higher volumes you may need more space, staff, or equipment, stepping fixed costs up." ], [ "How does this help pricing?", "It shows the minimum sales needed at each price point, letting you test whether a price is viable." ] ] }, { "slug": "breaker-size-calculator", "name": "Breaker Size Calculator", "canonical_url": "https://boringtoolskit.com/breaker-size-calculator/", "category": "Energy & Electrical", "description": "Breaker size calculator: breaker amps from load watts.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "brick-calculator", "name": "Brick Calculator", "canonical_url": "https://boringtoolskit.com/brick-calculator/", "category": "Construction & Measurement", "description": "Brick calculator: estimate bricks for a wall from dimensions, brick size, and mortar joints.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "btu-calculator", "name": "BTU Calculator", "canonical_url": "https://boringtoolskit.com/btu-calculator/", "category": "Everyday Calculators", "description": "Estimate the BTUs needed to heat or cool a room based on size and conditions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/square-footage-calculator/", "/electricity-cost-calculator/", "/heat-index-calculator/" ], "answer": "Estimate the BTUs needed to heat or cool a room based on size and conditions.", "formula": "Base BTU = room volume (L × W × H) × 1.5. Additions: sun exposure = sun% × base; people = people × 500 BTU. Total = base + sun adjustment + people adjustment. The result is the cooling capacity in BTU/hour.", "example": "A 15 × 12 × 8 ft room (1,440 cu ft): base = 1,440 × 1.5 = 2,160 BTU. With 20% sun exposure (+432) and 2 people (+1,000): total ≈ 3,592 BTU/hr.", "assumptions": [ "About 1.5 BTU per cubic foot of room volume.", "Each occupant adds about 500 BTU/hr.", "Average insulation and window conditions." ], "sources": [ { "organization": "Wikipedia", "title": "British thermal unit", "url": "https://en.wikipedia.org/wiki/British_thermal_unit" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a BTU?", "A British thermal unit — the energy to raise one pound of water by 1°F. Air conditioner capacity is rated in BTU per hour." ], [ "How many BTU do I need for a room?", "A common rule: room volume × 1.5, plus 500 BTU per person and a sun-exposure adjustment. A 15×12×8 ft room needs roughly 3,600 BTU/hr before unit sizes." ], [ "What happens if my AC is too big?", "It short-cycles — cooling quickly then turning off — which wastes energy and leaves humidity high. Oversizing is a common mistake." ], [ "What happens if it's too small?", "It runs constantly, struggles to reach the set temperature, and wears out faster." ], [ "How does sun exposure matter?", "Sunlit rooms gain heat through windows and walls, so they need more capacity. West-facing rooms get the hardest afternoon load." ], [ "Is this an exact load calculation?", "No — it's a rule of thumb. A Manual J calculation accounts for insulation, windows, climate, and appliances for exact sizing." ], [ "What sizes do window ACs come in?", "Commonly 5,000, 6,000, 8,000, 10,000, and 12,000 BTU — pick the closest size at or above your estimate." ], [ "How many BTU do I need per square foot?", "About 20 BTU per square foot under typical conditions, adjusted for sun, insulation, and ceiling height." ], [ "Is bigger always better for AC?", "No — oversizing causes short-cycling, poor dehumidification, and higher bills." ], [ "How do I convert BTU to watts?", "Multiply BTU/hr by 0.293." ] ] }, { "slug": "budget-planner-calculator", "name": "Budget Planner Calculator", "canonical_url": "https://boringtoolskit.com/budget-planner-calculator/", "category": "Finance & Investing", "description": "Budget planner calculator: monthly income minus fixed costs and spending.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "buffer-solution-calculator", "name": "Buffer Solution Calculator", "canonical_url": "https://boringtoolskit.com/buffer-solution-calculator/", "category": "Chemistry", "description": "Calculate buffer pH using the Henderson-Hasselbalch equation.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/ph-calculator/", "/molarity-calculator/", "/equilibrium-constants-calculator/" ], "answer": "Calculate buffer pH using the Henderson-Hasselbalch equation.", "formula": "Henderson–Hasselbalch: pH = pKa + log₁₀([conjugate base] ÷ [weak acid]).", "example": "A buffer with pKa 4.75, [A⁻] = 0.2 M and [HA] = 0.1 M: pH = 4.75 + log₁₀(2.0) = 4.75 + 0.301 = 5.05.", "assumptions": [ "pKa and the concentrations of the weak acid and conjugate base are entered.", "The approximation holds when the acid and base concentrations are within the buffering range.", "The calculation assumes ideal dilute aqueous solution at 25°C." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "business-days-calculator", "name": "Business Days Calculator", "canonical_url": "https://boringtoolskit.com/business-days-calculator/", "category": "Time & Work", "description": "Count weekdays between two dates with an optional number of excluded holidays.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/date-difference-calculator/", "/date-calculator-workspace/", "/age-calculator/" ], "answer": "Count weekdays between two dates with an optional number of excluded holidays.", "formula": "Counts the weekdays (Monday–Friday) between a start and end date, inclusive of both.", "example": "A Monday through Friday week contains 5 business days.", "assumptions": [ "Business days = Monday–Friday.", "Both dates are included in the count.", "Holidays are excluded by the user separately." ], "sources": [ { "organization": "Wikipedia", "title": "Business day", "url": "https://en.wikipedia.org/wiki/Business_day" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a business day?", "A working day — Monday through Friday in most places, excluding weekends and holidays." ], [ "How do I count business days?", "Count weekdays between the dates, inclusive. A Monday–Friday span = 5 business days." ], [ "Does it include holidays?", "No — the tool excludes weekends only. Check your region's holiday calendar for precise counts." ], [ "How many business days are in a week?", "Five — unless a holiday falls in it." ], [ "Does '5 business days' mean a calendar week?", "Usually slightly more: 5 business days from Monday lands on the following Monday (excluding weekends)." ], [ "Can I count backwards?", "The tool counts between chosen dates — reverse the dates to count an earlier span." ], [ "Why do shipping estimates use business days?", "Carriers and offices operate on weekdays, so transit times are quoted in working days." ], [ "Do weekends count as business days?", "No — Saturday and Sunday are excluded." ], [ "Do holidays count?", "Usually not — the calculator can skip US federal and custom holidays." ], [ "What is 5 business days from Wednesday?", "The following Wednesday — the weekend pushes it forward." ] ] }, { "slug": "business-loan-calculator", "name": "Business Loan Calculator", "canonical_url": "https://boringtoolskit.com/business-loan-calculator/", "category": "Finance & Investing", "description": "Business loan calculator: SBA-style loan payment.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "business-name-generator", "name": "Business Name Generator", "canonical_url": "https://boringtoolskit.com/business-name-generator/", "category": "Generators", "description": "Generate business and brand name ideas from your industry and style — privacy-clean, no sign-up.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "August 2026", "related_urls": [ "/slogan-generator/", "/qr-generator/", "/invoice-gen/" ], "answer": "Generate business and brand name ideas from your industry and style — privacy-clean, no sign-up.", "formula": "The generator combines your industry with a style-specific prefix and a curated suffix list. Each pass picks random combinations and de-duplicates them, returning the requested number of unique candidates.", "example": "Enter coffee with a Modern style to get names like 'Nova Coffee', 'Coffee Base', or 'Loop Coffee Co.'.", "assumptions": [ "Generated output is a starting point, not final professional copy.", "Nothing you type leaves your browser.", "Results vary on each run because selection is random." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculation methodology and verification standard", "url": "/methodology/" } ], "faqs": [ [ "Are these names trademarked?", "No. The generator produces template-based name ideas for brainstorming. You should check trademark and domain availability before using one." ], [ "Can I use the names commercially?", "You may use them as starting ideas, but you're responsible for verifying that a name isn't already in use or trademarked." ], [ "Why do I get different names each time?", "The generator uses random combinations, so each run produces a new set. Increase the count to see more options." ] ] }, { "slug": "c1v1-c2v2-calculator", "name": "C1V1 = C2V2 Calculator", "canonical_url": "https://boringtoolskit.com/c1v1-c2v2-calculator/", "category": "Chemistry", "description": "Solve for concentration or volume in C1V1 = C2V2 dilution equations.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/dilution-calculator/", "/serial-dilution-calculator/", "/molarity-calculator/" ], "answer": "Solve for concentration or volume in C1V1 = C2V2 dilution equations.", "formula": "C₁V₁ = C₂V₂; solve for whichever of the four variables (C₁, V₁, C₂, V₂) is left blank.", "example": "With a stock of 5.0 M and a target of 0.5 M in 100 mL: V₁ = (0.5 × 100) ÷ 5.0 = 10 mL of stock diluted to 100 mL.", "assumptions": [ "Provide any three values and leave exactly one blank.", "Concentration and volume units must be consistent.", "The relationship assumes the moles of solute are conserved through dilution." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "caffeine-half-life-calculator", "name": "Caffeine Half-Life Calculator", "canonical_url": "https://boringtoolskit.com/caffeine-half-life-calculator/", "category": "Health", "description": "Caffeine half-life calculator: how much caffeine remains in your system over time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "caffeine-intake-calculator", "name": "Caffeine Intake Calculator", "canonical_url": "https://boringtoolskit.com/caffeine-intake-calculator/", "category": "Food & Cooking", "description": "Caffeine intake calculator: total daily caffeine from coffee, tea, energy drinks, and soda.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "cagr-calculator", "name": "CAGR Calculator", "canonical_url": "https://boringtoolskit.com/cagr-calculator/", "category": "Finance & Investing", "description": "Calculate compound annual growth rate from starting value, ending value, and elapsed years.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/future-value-calculator/", "/dca-investment-calculator/", "/stock-calc/" ], "answer": "Calculate compound annual growth rate from starting value, ending value, and elapsed years.", "formula": "CAGR = (ending value ÷ starting value)^(1 ÷ years) − 1.", "example": "", "assumptions": [ "No contributions or withdrawals occur between the endpoints.", "The time period is measured in years.", "CAGR is a smoothed historical rate, not a forecast." ], "sources": [ { "organization": "Investor.gov", "title": "Understanding investment returns", "url": "https://www.investor.gov/introduction-investing/investing-basics/glossary/annual-return" }, { "organization": "SEC", "title": "Investor bulletin: performance claims", "url": "https://www.sec.gov/resources-for-investors/investor-alerts-bulletins/investor-bulletin-performance-claims" } ], "faqs": [ [ "What is a CAGR calculator and how does it work?", "A cagr calculator computes the Compound Annual Growth Rate of an investment over a specified time period. It uses your starting value, ending value, and the number of years to calculate the average annual growth rate, all processed instantly in your browser." ], [ "Is the cagr calculator free and do I need to create an account?", "Yes, the cagr calculator is completely free to use with no signup required. It runs entirely in your browser, so your data is never stored on a server and your privacy is fully protected." ], [ "How accurate are the results from the cagr calculator?", "The cagr calculator applies the standard CAGR formula and delivers mathematically precise results. However, it assumes a smooth, consistent growth rate and does not account for volatility or market fluctuations, so treat it as an estimate rather than a guaranteed outcome." ] ] }, { "slug": "calorie-calc", "name": "Calorie Calculator", "canonical_url": "https://boringtoolskit.com/calorie-calc/", "category": "Health", "description": "Estimate daily calories and macros from simple inputs.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/bmr-tdee-calculator/", "/macro-planning-calculator/", "/body-fat-calculator/" ], "answer": "Estimate daily calories and macros from simple inputs.", "formula": "Estimates daily calories with the Mifflin-St Jeor equation: BMR = 10×kg + 6.25×cm − 5×age + 5 (male) or −161 (female), then multiplied by an activity factor (1.2–1.9).", "example": "A 30-year-old male, 180 lb, 5'10\", sedentary: BMR ≈ 1,783 → maintenance ≈ 2,140 calories/day.", "assumptions": [ "The Mifflin-St Jeor equation applies.", "The activity factor is realistic.", "Weight-change goals use standard deficit/surplus ranges." ], "sources": [ { "organization": "Wikipedia", "title": "Basal metabolic rate", "url": "https://en.wikipedia.org/wiki/Basal_metabolic_rate" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate daily calories?", "Mifflin-St Jeor BMR × activity factor: BMR 1,783 × 1.2 ≈ 2,140 kcal in the example." ], [ "What is BMR?", "Basal metabolic rate — the calories your body burns at rest just to function." ], [ "How much should I cut to lose weight?", "A 300–500 kcal daily deficit loses about 0.5–1 lb per week." ], [ "What activity factor should I use?", "Be honest: 1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 very active." ], [ "Is this exact?", "No — it's an estimate. Track your weight and adjust by 100–200 kcal." ], [ "Why do I need more calories than my friend?", "Size, muscle mass, age, and activity all change the number." ], [ "Should I eat back exercise calories?", "Generally not — exercise calories are overestimated by trackers." ] ] }, { "slug": "calorie-deficit-calculator", "name": "Calorie Deficit Calculator", "canonical_url": "https://boringtoolskit.com/calorie-deficit-calculator/", "category": "Health", "description": "Calorie deficit calculator: weight-loss timeline from daily deficit and target pounds.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "calorie-target-calculator", "name": "Calorie Target Calculator", "canonical_url": "https://boringtoolskit.com/calorie-target-calculator/", "category": "Health", "description": "Calorie target calculator: maintenance, deficit, and surplus targets from weight, height, age, and activity.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "calories-burned-calculator", "name": "Calories Burned Calculator", "canonical_url": "https://boringtoolskit.com/calories-burned-calculator/", "category": "Everyday Calculators", "description": "Estimate calories burned during exercise using MET values and body weight.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/bmr-tdee-calculator/", "/one-rep-max-calculator/", "/ideal-weight-calculator/" ], "answer": "Estimate calories burned during exercise using MET values and body weight.", "formula": "Calories burned = MET × 3.5 × weight (kg) ÷ 200 × minutes. The MET value is the activity's metabolic equivalent from the Compendium of Physical Activities (e.g., ~3.5 walking, ~4.3 brisk walking, ~9.8 running at 6 mph). Weight in lb is converted: kg = lb × 0.453592.", "example": "A 70 kg person walking briskly (MET 4.3) for 30 minutes: 4.3 × 3.5 × 70 ÷ 200 × 30 ≈ 158 kcal.", "assumptions": [ "The MET value reflects the user's actual effort level.", "The formula is the standard ACSM estimation.", "Individual metabolic differences are not modeled." ], "sources": [ { "organization": "Compendium of Physical Activities", "title": "MET values for physical activities", "url": "https://pacompendium.com/" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How is calorie burn calculated?", "Calories = MET × 3.5 × weight (kg) ÷ 200 × minutes. MET is the activity's metabolic equivalent — a measure of its intensity." ], [ "What is a MET?", "A metabolic equivalent: 1 MET is resting energy use. Walking is about 3.5 METs, brisk walking 4.3, running at 6 mph about 9.8." ], [ "How accurate is this?", "It's a good estimate for a typical adult, but actual burn varies with fitness, terrain, and effort. Treat it as a planning number, not a precise measurement." ], [ "Does this include my resting burn?", "No — it's the calories burned during the activity only, on top of your BMR. Use the BMR/TDEE calculator for total daily burn." ], [ "How do I convert pounds to kilograms?", "Divide by 2.205 (kg = lb × 0.453592). The tool does this automatically when you enter pounds." ], [ "Why does intensity matter?", "Higher MET values mean more calories per minute — running burns roughly 3× walking for the same time. Choose the MET that matches your actual effort." ], [ "Is exercise necessary for weight loss?", "Calories burned by exercise help, but total daily energy balance (intake vs TDEE) drives weight change. Exercise also builds fitness and muscle." ] ] }, { "slug": "candy-temperature-calculator", "name": "Candy Temperature Calculator", "canonical_url": "https://boringtoolskit.com/candy-temperature-calculator/", "category": "Food & Cooking", "description": "Candy temperature calculator: sugar stages from temperature.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "cap-rate-calculator", "name": "Cap Rate Calculator", "canonical_url": "https://boringtoolskit.com/cap-rate-calculator/", "category": "Finance & Investing", "description": "Calculate the capitalization rate on a rental property. Enter property value and net operating income (NOI) for unlevered yield.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/net-operating-income-calculator/", "/rental-yield-calculator/", "/cash-on-cash-return-calculator/" ], "answer": "Calculate the capitalization rate on a rental property. Enter property value and net operating income (NOI) for unlevered yield.", "formula": "Capitalization rate = net operating income ÷ property value × 100. It is an unlevered yield: operating income (before debt service) divided by the full purchase price or current value.", "example": "A property with $60,000 net operating income (NOI) and a $700,000 purchase price has a cap rate of $60,000 ÷ $700,000 = 8.57%.", "assumptions": [ "NOI excludes debt service, income tax, and one-time capital expenditures.", "Property value can be a recent appraisal, the purchase price, or a current market estimate — use the same basis when comparing.", "Operating expenses shown are recurring annual costs (taxes, insurance, maintenance, management)." ], "sources": [ { "organization": "Investopedia", "title": "Capitalization Rate", "url": "https://www.investopedia.com/terms/c/cap-rate.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a good cap rate?", "A good cap rate depends on market and risk. Many income-property investors look for 5–10%; a higher cap often reflects higher risk or a lower-quality area, while a lower cap suggests a stable, lower-risk market." ], [ "How is cap rate different from ROI?", "Cap rate divides NOI by total property value (unlevered), while ROI typically divides annual profit by the cash you invested. ROI accounts for your down payment and financing; cap rate does not." ], [ "Does cap rate include mortgage payments?", "No. Cap rate uses net operating income before debt service, so it ignores the mortgage entirely. Use cash-on-cash return or total ROI for a financed view." ], [ "Can I use cap rate to price a property?", "Yes — solve value = NOI ÷ cap rate. If you target a 7% cap rate and NOI is $60,000, the value is about $857,000." ], [ "Why does the same property show different cap rates?", "Because basis matters: purchase price, appraisal, and current market value all give different cap rates. Compare like-for-like." ], [ "Is a higher cap rate always better?", "Not necessarily. A high cap rate can mean a genuinely higher yield or a riskier property. Look at the market, condition, and tenant quality." ], [ "What is a NOI?", "Net operating income is gross income minus operating expenses (excluding debt service, taxes, and capex). It is the numerator of the cap-rate formula." ] ] }, { "slug": "capacitance-calculator", "name": "Capacitance Calculator", "canonical_url": "https://boringtoolskit.com/capacitance-calculator/", "category": "Energy & Electrical", "description": "Capacitance calculator: capacitance from stored energy and voltage.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "capital-gains-calculator", "name": "Capital Gains Calculator", "canonical_url": "https://boringtoolskit.com/capital-gains-calculator/", "category": "Finance & Investing", "description": "Capital gains calculator: tax on an asset sale from sell price, cost basis, and your capital gains rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "car-insurance-estimator", "name": "Car Insurance Estimator", "canonical_url": "https://boringtoolskit.com/car-insurance-estimator/", "category": "Vehicles", "description": "Car insurance estimator: rough annual premium from vehicle value, driver age, and record.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "car-loan-refinance-calculator", "name": "Car Loan Refinance Calculator", "canonical_url": "https://boringtoolskit.com/car-loan-refinance-calculator/", "category": "Vehicles", "description": "Car loan refinance calculator: monthly savings from refinancing a car loan.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "cash-flow-calculator", "name": "Real Estate Cash Flow Calculator", "canonical_url": "https://boringtoolskit.com/cash-flow-calculator/", "category": "Finance & Investing", "description": "Estimate your monthly real estate cash flow. Enter rental income and all operating costs to see positive or negative cash flow. Private.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/net-operating-income-calculator/", "/cap-rate-calculator/", "/rental-yield-calculator/" ], "answer": "Estimate your monthly real estate cash flow. Enter rental income and all operating costs to see positive or negative cash flow. Private.", "formula": "Monthly cash flow = gross income (rent + other) − total monthly expenses (mortgage payment + taxes + insurance + maintenance + other operating costs). Positive cash flow means the property earns more than it costs to hold each month.", "example": "Rent of $1,650 + $80 other income = $1,730 income; mortgage $1,200 + taxes $150 + insurance $60 + maintenance $100 + misc $70 = $1,580 expenses; cash flow = $150 / month.", "assumptions": [ "Expenses are entered as recurring monthly amounts.", "Mortgage payment is the total P&I monthly cost.", "Maintenance and 'other' are estimates — actual costs may be higher." ], "sources": [ { "organization": "Consumer Financial Protection Bureau", "title": "Owning a Home", "url": "https://www.consumerfinance.gov/owning-a-home/" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What counts as cash flow income?", "Gross monthly rental income plus other income such as parking, storage, laundry, or pet fees." ], [ "What counts as cash flow expenses?", "The mortgage payment, property taxes, insurance, maintenance, management, utilities you pay, and other operating costs." ], [ "Is positive cash flow always good?", "It means the property covers its own carrying cost, which is generally desirable. But it doesn't capture appreciation or tax benefits." ], [ "Should I include a vacancy allowance?", "Yes — add a vacancy reserve (often 5–8% of rent) so your estimate survives an empty month." ], [ "How is cash flow different from NOI?", "NOI is before debt service; cash flow is after the mortgage. Cash flow is the more conservative 'does it pay itself' number." ], [ "Why does my cash flow change after closing?", "Your actual mortgage payment and repairs may differ from estimates. Recalculate monthly with real numbers." ], [ "What is a good monthly cash flow for a rental?", "It varies by market. A common rule of thumb is a modest positive amount that covers 100% of owning costs; the key is durability, not a large number." ] ] }, { "slug": "cash-flow-runway-calculator", "name": "Cash-Flow Runway Calculator", "canonical_url": "https://boringtoolskit.com/cash-flow-runway-calculator/", "category": "Seller & Business", "description": "Model monthly cash runway, depletion month, lowest cash, and operating break-even from editable growth assumptions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/break-even-units-calculator/", "/customer-lifetime-value-calculator/", "/price-increase-impact-calculator/" ], "answer": "Model monthly cash runway, depletion month, lowest cash, and operating break-even from editable growth assumptions.", "formula": "Monthly burn = monthly expenses − monthly revenue. Runway = starting cash ÷ burn. The tool also projects depletion month and break-even month with optional revenue/expense growth.", "example": "$50,000 cash with $10,000 revenue and $12,000 expenses: burn = $2,000/month, so runway ≈ 25 months.", "assumptions": [ "Monthly revenue and expenses are steady (or follow the entered growth).", "The horizon is up to 120 months.", "No funding events or irregular expenses are modeled." ], "sources": [ { "organization": "Wikipedia", "title": "Cash flow", "url": "https://en.wikipedia.org/wiki/Cash_flow" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is cash runway?", "How many months your business can operate before cash runs out, at your current burn rate." ], [ "How do I calculate it?", "Burn = monthly expenses − monthly revenue; runway = cash ÷ burn. $50,000 ÷ $2,000 = 25 months." ], [ "What is the burn rate?", "Net cash consumed per month — expenses minus revenue. Negative burn (profit) extends runway indefinitely." ], [ "How much runway should I have?", "6–12 months is a common safety target for startups; less than 6 is action territory." ], [ "What can I do to extend runway?", "Cut non-essential costs, raise prices, accelerate collections, reduce inventory, or raise capital." ], [ "What is the break-even month?", "The month when revenue first covers expenses — cash flow turns positive and runway stops shrinking." ], [ "Is the projection accurate?", "It's as accurate as your inputs. Re-run it monthly with real numbers and treat growth assumptions as scenarios." ], [ "How do I calculate runway?", "Current cash ÷ monthly net burn (spending minus revenue)." ], [ "What is the difference between gross and net burn?", "Gross is total spending; net subtracts revenue — runway uses net." ], [ "How much runway is healthy?", "12+ months is comfortable; under 6 months triggers immediate cost and revenue actions." ], [ "How do I extend runway?", "Cut burn, raise revenue, or raise capital — the calculator shows each lever's effect." ] ] }, { "slug": "cash-on-cash-return-calculator", "name": "Cash-on-Cash Return Calculator", "canonical_url": "https://boringtoolskit.com/cash-on-cash-return-calculator/", "category": "Finance & Investing", "description": "Calculate cash-on-cash return on a rental property. Enter annual cash flow and total cash invested for yield on the cash you put in.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/rental-yield-calculator/", "/cash-flow-calculator/", "/cap-rate-calculator/" ], "answer": "Calculate cash-on-cash return on a rental property. Enter annual cash flow and total cash invested for yield on the cash you put in.", "formula": "Cash-on-cash return = annual pre-tax cash flow ÷ total cash invested × 100. It measures the yield on the cash you actually put in (down payment + closing costs), giving a financing-aware view of return.", "example": "If annual pre-tax cash flow is $9,000 and you invested $100,000 cash, cash-on-cash return = $9,000 ÷ $100,000 = 9.0%.", "assumptions": [ "Annual cash flow is pre-tax and before any depreciation benefit.", "Total cash invested includes down payment and closing costs but not loan proceeds.", "The result is a single-year snapshot, not a lifetime return." ], "sources": [ { "organization": "Investopedia", "title": "Cash-on-Cash Return", "url": "https://www.investopedia.com/terms/c/cashoncashreturn.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is cash-on-cash return?", "The annual pre-tax cash yield on the cash you invested in a property, expressed as a percentage." ], [ "How is it different from cap rate?", "Cap rate is unlevered (on total value); cash-on-cash uses your actual cash down payment and includes the mortgage." ], [ "What cash counts as 'invested'?", "Your down payment plus closing costs and any capital you put toward improvements — the money you're risking." ], [ "Is 8% cash-on-cash good?", "It depends on your alternative return and risk. Many investors target 8–12%, but a stable property at 6% can beat a risky one at 12%." ], [ "Does it include appreciation?", "No. Cash-on-cash is a cash-flow snapshot. Add total return (appreciation + principal paydown) for full picture." ], [ "How does leverage affect it?", "More leverage (smaller down payment) can raise cash-on-cash if the cash flow is positive, but it also raises risk." ], [ "Why does my return change?", "Because your down payment and financing terms change it. Vary those inputs to see the range." ] ] }, { "slug": "cat-age-calculator", "name": "Cat Age Calculator", "canonical_url": "https://boringtoolskit.com/cat-age-calculator/", "category": "Pets", "description": "Cat age calculator: cat years to human years.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "cat-food-calculator", "name": "Cat Food Calculator", "canonical_url": "https://boringtoolskit.com/cat-food-calculator/", "category": "Pets", "description": "Cat food calculator: daily calories and cups from cat weight.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "cat-litter-calculator", "name": "Cat Litter Calculator", "canonical_url": "https://boringtoolskit.com/cat-litter-calculator/", "category": "Pets", "description": "Cat litter calculator: litter needed for a multi-cat home.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "cd-calculator", "name": "CD Calculator", "canonical_url": "https://boringtoolskit.com/cd-calculator/", "category": "Everyday Calculators", "description": "Calculate the maturity value and interest earned on a Certificate of Deposit over its term.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/compound-interest/", "/savings-goal-calculator/", "/bond-calculator/" ], "answer": "Calculate the maturity value and interest earned on a Certificate of Deposit over its term.", "formula": "Maturity value = deposit × (1 + APY ÷ compounds)^(compounds × years); interest earned = maturity value − deposit. The APY is compounded at the selected frequency over the CD term.", "example": "A $10,000 CD at 5% APY compounded monthly for 3 years: $10,000 × (1 + 0.05/12)^(12×3) ≈ $11,614.72, so interest earned ≈ $1,614.72.", "assumptions": [ "The APY stays constant for the full term.", "Interest is compounded at the selected frequency.", "No withdrawals are made before maturity." ], "sources": [ { "organization": "Investopedia", "title": "Certificate of Deposit (CD)", "url": "https://www.investopedia.com/terms/c/certificateofdeposit.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a CD?", "A certificate of deposit is a savings account that pays a fixed interest rate (APY) for a set term — commonly 3 months to 5 years — in exchange for locking your money." ], [ "What is APY vs APR?", "APY includes the effect of compounding, so it is the true annual return. APR is the simple annual rate before compounding. For CDs, compare APYs." ], [ "What happens if I withdraw early?", "You pay an early-withdrawal penalty, usually a number of months of interest (e.g., 90–180 days). That can eat most or all of your earnings, so plan to hold to maturity." ], [ "Are CDs insured?", "CDs at FDIC-insured banks are insured up to $250,000 per depositor, per institution, per ownership category (NCUA for credit unions)." ], [ "How is a CD ladder built?", "Split your money across CDs with staggered maturities (e.g., 1, 2, and 3 years). As each matures, reinvest at the current rate — you get longer-term rates while keeping regular access to cash." ], [ "Is a longer term always better?", "Usually a longer term pays a higher APY, but you give up access and face more inflation risk. A longer term only wins if you hold to maturity and rates don't rise sharply." ], [ "Can I add money to a CD?", "Generally no — CDs take a single deposit. To save more, buy another CD or use a regular savings account." ], [ "How do I calculate CD earnings?", "Deposit × (1 + APY)^years, adjusted for the bank's compounding." ], [ "What is the early withdrawal penalty?", "Typically 3–6 months of interest — enough to erase most of a short-term yield." ], [ "What is a CD ladder?", "Staggered maturities across terms so money becomes available regularly." ], [ "CD or high-yield savings?", "CDs lock the rate; savings stay liquid — compare the small yield difference." ] ] }, { "slug": "ceiling-fan-size-calculator", "name": "Ceiling Fan Size Calculator", "canonical_url": "https://boringtoolskit.com/ceiling-fan-size-calculator/", "category": "Construction & Measurement", "description": "Ceiling fan size calculator: blade span by room size.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "ceiling-tile-calculator", "name": "Ceiling Tile Calculator", "canonical_url": "https://boringtoolskit.com/ceiling-tile-calculator/", "category": "Construction & Measurement", "description": "Ceiling tile calculator: 2x2 drop-ceiling tiles for a room.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "chair-rail-calculator", "name": "Chair Rail Calculator", "canonical_url": "https://boringtoolskit.com/chair-rail-calculator/", "category": "Construction & Measurement", "description": "Chair rail calculator: classic height from ceiling height.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "chargaff-rule-calculator", "name": "Chargaff Rule Calculator", "canonical_url": "https://boringtoolskit.com/chargaff-rule-calculator/", "category": "Biology", "description": "Chargaff rule calculator: predict T, G, and C percentages from adenine percentage in double-stranded DNA.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "chess-elo-calculator", "name": "Chess Elo Calculator", "canonical_url": "https://boringtoolskit.com/chess-elo-calculator/", "category": "Gaming", "description": "Chess Elo calculator: expected score and new rating after a game using the standard Elo formula.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "chi-square-calculator", "name": "Chi-Square Goodness of Fit Calculator", "canonical_url": "https://boringtoolskit.com/chi-square-calculator/", "category": "Statistics", "description": "Chi-square calculator: goodness-of-fit test statistic from observed vs expected counts.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "child-care-cost-calculator", "name": "Child Care Cost Calculator", "canonical_url": "https://boringtoolskit.com/child-care-cost-calculator/", "category": "Finance & Investing", "description": "Child care cost calculator: annual cost of daycare or nanny care.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "children-size-converter", "name": "Children Size Converter", "canonical_url": "https://boringtoolskit.com/children-size-converter/", "category": "Converters", "description": "Children size converter: US to EU kids clothing sizes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "chinese-zodiac-calculator", "name": "Chinese Zodiac Calculator", "canonical_url": "https://boringtoolskit.com/chinese-zodiac-calculator/", "category": "Astrology", "description": "Chinese zodiac calculator: animal sign and element from birth year, with lunar-new-year caveat.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "cholesterol-ratio-calculator", "name": "Cholesterol Ratio Calculator", "canonical_url": "https://boringtoolskit.com/cholesterol-ratio-calculator/", "category": "Health", "description": "Cholesterol ratio calculator: total-to-HDL and LDL-to-HDL ratios from a lipid panel.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "chord-progression-generator", "name": "Chord Progression Generator", "canonical_url": "https://boringtoolskit.com/chord-progression-generator/", "category": "Music & Audio", "description": "Chord progression generator: common diatonic progressions in any key, computed locally.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "circle-area-calculator", "name": "Circle Area Calculator", "canonical_url": "https://boringtoolskit.com/circle-area-calculator/", "category": "Everyday Calculators", "description": "Circle area calculator: area and circumference from radius.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-27", "related_urls": [], "answer": "Circle area calculator: area and circumference from radius.", "formula": "Area = π × r², where r is the radius. Circumference = 2 × π × r.", "example": "For r = 5 m: area ≈ 78.54 m², circumference ≈ 31.42 m.", "assumptions": [ "Standard geometric or arithmetic definitions apply.", "Inputs use the units you choose.", "Results are estimates, not professional advice." ], "sources": [ { "organization": "Standard mathematics definitions", "title": "Arithmetic and geometry formulas", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "circle-calculator", "name": "Circle Calculator", "canonical_url": "https://boringtoolskit.com/circle-calculator/", "category": "Everyday Calculators", "description": "Find a circle's area, circumference, diameter, or radius from any one value.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/pythagorean-theorem-calculator/", "/triangle-calculator/", "/surface-area-calculator/" ], "answer": "Find a circle's area, circumference, diameter, or radius from any one value.", "formula": "From radius r: diameter d = 2r, circumference c = 2πr, area A = πr². The tool also derives r from a known diameter (r = d/2), circumference (r = c/(2π)), or area (r = √(A/π)).", "example": "A circle with radius 5: diameter = 10, circumference = 2π×5 ≈ 31.4159, area = π×25 ≈ 78.5398.", "assumptions": [ "The shape is a perfect circle.", "π is approximated to standard precision.", "The input value is positive." ], "sources": [ { "organization": "Math Is Fun", "title": "Circle", "url": "https://www.mathsisfun.com/geometry/circle.html" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate the circumference of a circle?", "Circumference = 2πr, or π × diameter. A radius-5 circle has circumference ≈ 31.42." ], [ "How do I calculate the area of a circle?", "Area = πr². A radius-5 circle has area ≈ 78.54 square units." ], [ "What is the relationship between radius and diameter?", "The diameter is twice the radius: d = 2r. The radius is half the diameter." ], [ "What is π?", "The constant ratio of a circle's circumference to its diameter, ≈ 3.14159. It appears in every circle formula." ], [ "Can I find the radius from the circumference?", "Yes: r = c ÷ (2π). From the area: r = √(A ÷ π)." ], [ "Why is circumference also called perimeter?", "Circumference is the circle's perimeter — the distance around the outside. The term 'perimeter' is general; 'circumference' is specific to circles." ], [ "Does this work for ellipses?", "No — ellipses have no single radius, and their circumference requires an approximation formula, not 2πr." ], [ "How do I calculate circumference?", "2πr, or π × diameter." ], [ "Can I find the radius from the area?", "Yes — √(area ÷ π)." ], [ "How much bigger is a 16-inch pizza than 12-inch?", "About 78% more area — bigger than the diameter difference suggests." ] ] }, { "slug": "citation-formatter", "name": "Citation Formatter", "canonical_url": "https://boringtoolskit.com/citation-formatter/", "category": "Everyday Calculators", "description": "Format a book, website, or article into APA and MLA citations from author, title, publisher, year, and URL.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/markdown-table-generator/", "/text-case/", "/word-counter/" ], "answer": "Format a book, website, or article into APA and MLA citations from author, title, publisher, year, and URL.", "formula": "Formats source details into APA and MLA citations: author, year, title, publisher/venue, and URL, following each style's punctuation and order rules.", "example": "APA: Smith, J. (2026). *Title of work*. Publisher. | MLA: Smith, John. *Title of Work*. Publisher, 2026.", "assumptions": [ "The entered metadata is accurate.", "The source is a common type (book, article, webpage).", "The style guide version matches the formatter." ], "sources": [ { "organization": "Wikipedia", "title": "Citation", "url": "https://en.wikipedia.org/wiki/Citation" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I format a citation?", "Enter the author, year, title, and publisher — the tool applies APA or MLA formatting." ], [ "What's the difference between APA and MLA?", "APA puts the year after the author (social sciences); MLA puts it at the end (humanities)." ], [ "Do I italicize titles?", "Yes — book and journal titles are italicized in both styles; the formatter marks them." ], [ "How do I cite a website?", "Include author, year, title, site name, and URL — the formatter handles it." ], [ "Is this citation complete?", "It formats what you enter — verify the metadata against the source." ], [ "What about in-text citations?", "The tool formats references; in-text citations follow the same author-year (APA) or author-page (MLA) pattern." ], [ "Is APA or MLA more common?", "APA dominates the social sciences; MLA the humanities. Follow your assignment's requirement." ], [ "What is a citation formatter?", "A tool that formats references in APA, MLA, Chicago, and Harvard styles." ], [ "What are the main styles?", "APA (social sciences), MLA (humanities), Chicago (history/publishing), Harvard (business)." ], [ "Do I still need to check citations?", "Yes — details like DOIs and page numbers need a final human pass." ], [ "What is an in-text citation?", "The short parenthetical reference pointing to the full entry." ] ] }, { "slug": "closing-cost-calculator", "name": "Closing Cost Calculator", "canonical_url": "https://boringtoolskit.com/closing-cost-calculator/", "category": "Finance & Investing", "description": "Estimate closing costs on a home purchase. Enter price, down payment, and typical fee percentages for an itemized total.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/mortgage-payment-calculator/", "/down-payment-calculator/", "/loan-to-value-calculator/" ], "answer": "Estimate closing costs on a home purchase. Enter price, down payment, and typical fee percentages for an itemized total.", "formula": "Total closing costs = down payment + lender fees + title fees + government fees + other costs. Each component (lender, title, government, other) is a user-entered dollar or percentage figure added together.", "example": "On a $300,000 home with a 20% down payment ($60,000), $4,000 lender fees, $2,500 title fees, $1,500 government fees, and $1,000 other costs, total closing costs = $9,000 (plus the $60,000 down payment).", "assumptions": [ "Closing costs exclude the down payment itself.", "Fee figures are user-entered estimates — actuals vary by lender and location.", "Transfer taxes and title costs differ by state and county." ], "sources": [ { "organization": "Investopedia", "title": "Closing Costs", "url": "https://www.investopedia.com/terms/c/closing-costs.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How much are closing costs?", "Typically 2–5% of the loan amount, on top of your down payment. Fees vary by lender and location." ], [ "Are closing costs included in the down payment?", "No. Closing costs are separate from the down payment. You need cash for both." ], [ "What are the biggest closing costs?", "Lender fees (origination, points) and title insurance are usually the largest. Government recording and transfer taxes vary by state." ], [ "Can I get the seller to pay closing costs?", "Sometimes. A seller credit can offset some buyer closing costs, and a lender credit can lower upfront fees in exchange for a slightly higher rate." ], [ "Do I pay closing costs with a refinance?", "Yes, refinances have closing costs too, but they may be smaller. Roll them in or pay them upfront depending on your break-even timeline." ], [ "Why do closing costs vary by state?", "Transfer taxes, recording fees, and title requirements differ by state and county, so the same-priced home can have very different closing costs." ], [ "What is prepaid interest?", "Interest paid at closing for the days between closing and the first payment. It's a common closing-cost line item." ] ] }, { "slug": "clothing-size-converter", "name": "Clothing Size Converter", "canonical_url": "https://boringtoolskit.com/clothing-size-converter/", "category": "Travel", "description": "Clothing size converter: international clothing size conversion (US, UK, EU).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "coefficient-of-variation-calculator", "name": "Coefficient of Variation Calculator", "canonical_url": "https://boringtoolskit.com/coefficient-of-variation-calculator/", "category": "Everyday Calculators", "description": "Calculate the coefficient of variation (relative standard deviation). Enter the mean and standard deviation to compare variability across data sets.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/standard-error-calculator/", "/variance-calculator/", "/statistics-calculator/" ], "answer": "Calculate the coefficient of variation (relative standard deviation). Enter the mean and standard deviation to compare variability across data sets.", "formula": "Coefficient of variation (CV) = (standard deviation ÷ mean) × 100. A CV below ~15% is often considered low relative spread.", "example": "A mean of 50 with a standard deviation of 5: CV = (5 ÷ 50) × 100 = 10.0%, which is a relatively tight spread. The same standard deviation on a mean of 500 would give CV = 1.0%.", "assumptions": [ "Mean must be non-zero to compute CV.", "CV is a relative (unit-free) measure of dispersion, useful for comparing data sets with different means.", "Lower CV suggests lower variability relative to the mean." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "NIST/SEMATECH e-Handbook of Statistical Methods", "url": "https://www.itl.nist.gov/div898/handbook/" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "coffee-cost-calculator", "name": "Coffee Cost Calculator", "canonical_url": "https://boringtoolskit.com/coffee-cost-calculator/", "category": "Food & Cooking", "description": "Coffee cost calculator: what your daily coffee habit really costs per year.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "coffee-ratio-calculator", "name": "Coffee Ratio Calculator", "canonical_url": "https://boringtoolskit.com/coffee-ratio-calculator/", "category": "Food & Cooking", "description": "Coffee ratio calculator: grams of coffee for water and ratio.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "cohens-d-calculator", "name": "Cohen's D Calculator", "canonical_url": "https://boringtoolskit.com/cohens-d-calculator/", "category": "Statistics", "description": "Cohen's d calculator: effect size between two groups.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "coin-flip", "name": "Coin Flip Tool", "canonical_url": "https://boringtoolskit.com/coin-flip/", "category": "Everyday Calculators", "description": "Flip one or up to 100 coins locally with secure browser randomness, counts, percentages, streaks, and sequence.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/dice-roller/", "/random-number-generator/", "/random-name-picker/" ], "answer": "Flip one or up to 100 coins locally with secure browser randomness, counts, percentages, streaks, and sequence.", "formula": "Simulates fair (or weighted) coin flips, counting heads and tails. A fair coin gives each outcome a 50% probability per flip.", "example": "10 fair flips might produce 6 heads and 4 tails — the count varies run to run, converging toward 50/50 over many flips.", "assumptions": [ "Each flip is independent.", "The default is a fair 50/50 coin.", "Results are generated with a uniform RNG." ], "sources": [ { "organization": "Wikipedia", "title": "Coin flipping", "url": "https://en.wikipedia.org/wiki/Coin_flipping" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I flip a coin?", "Set the number of flips and run it — the tool counts heads and tails." ], [ "Is a coin flip really 50/50?", "For a fair coin and fair flip, yes — each flip is independent." ], [ "Why did I get 7 heads in 10 flips?", "Short runs vary widely — 10 flips are noisy; the 50/50 split emerges over hundreds." ], [ "Is the coin 'due' for tails?", "No — flips are independent; past results don't affect the next one." ], [ "Can I use a weighted coin?", "Yes — the tool's bias option models a loaded coin." ], [ "What is this used for?", "Decisions, games, statistics demos, and testing randomness." ], [ "Is the RNG fair?", "It uses a uniform pseudorandom generator — good for practical purposes." ] ] }, { "slug": "college-cost-calculator", "name": "College Cost Calculator", "canonical_url": "https://boringtoolskit.com/college-cost-calculator/", "category": "Finance & Investing", "description": "College cost calculator: four-year total cost with tuition inflation.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "color-difference-calculator", "name": "Color Difference Calculator", "canonical_url": "https://boringtoolskit.com/color-difference-calculator/", "category": "Colors & Design", "description": "Color difference calculator: CIE76 delta E between two hex colors for design QA.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "color-gradient-calculator", "name": "Color Gradient Calculator", "canonical_url": "https://boringtoolskit.com/color-gradient-calculator/", "category": "Colors & Design", "description": "Color gradient calculator: interpolate between two hex colors and get a mid-tone blend.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "color-mixer-calculator", "name": "Color Mixer Calculator", "canonical_url": "https://boringtoolskit.com/color-mixer-calculator/", "category": "Colors & Design", "description": "Color mixer calculator: blend two hex colors by any percentage to predict a paint or digital mix.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "color-palette-generator", "name": "Color Palette Generator", "canonical_url": "https://boringtoolskit.com/color-palette-generator/", "category": "Colors & Design", "description": "Color palette generator: harmonic color schemes from a base hex color, computed locally.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "color-picker", "name": "Color Picker", "canonical_url": "https://boringtoolskit.com/color-picker/", "category": "Text & Developer Tools", "description": "Choose a color, inspect HEX, RGB, HSL, HSV, and CMYK values, and copy formats locally.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/hex-to-decimal/", "/random-number-generator/", "/qr-generator/" ], "answer": "Choose a color, inspect HEX, RGB, HSL, HSV, and CMYK values, and copy formats locally.", "formula": "Converts between color models: hex (#RRGGBB) ↔ RGB ↔ HSL, with HSV. RGB values are 0–255; HSL hue is 0–360° with saturation and lightness as percentages.", "example": "#FF0000 = rgb(255, 0, 0) = hsl(0°, 100%, 50%) — pure red.", "assumptions": [ "The color is for screen use (RGB family).", "Hex input uses the standard #RRGGBB form.", "Device calibration is outside the tool's scope." ], "sources": [ { "organization": "Wikipedia", "title": "HSL and HSV", "url": "https://en.wikipedia.org/wiki/HSL_and_HSV" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I convert hex to RGB?", "Split #RRGGBB into three byte values: #FF0000 = rgb(255, 0, 0). The tool does this instantly." ], [ "What is HSL?", "Hue (0–360°, the color family), saturation (0–100%, intensity), lightness (0–100%, brightness) — a more intuitive color model than RGB." ], [ "Why is #FF0000 red?", "FF is the maximum red byte (255), with zero green and zero blue — pure red." ], [ "Can I get CMYK for printing?", "No — this tool covers screen color models (hex, RGB, HSL). Print work needs CMYK conversion." ], [ "Why does my color look different on other screens?", "Displays aren't perfectly calibrated; the same hex renders slightly differently across devices." ], [ "How do I make a color lighter?", "Increase lightness in HSL — or add white in a design tool. Lowering lightness makes darker shades." ], [ "What's the difference between HSL and HSV?", "HSL and HSV both describe hue/saturation but differ in the third axis: lightness (HSL) vs value/brightness (HSV)." ] ] }, { "slug": "color-tint-shade-calculator", "name": "Color Tint Shade Calculator", "canonical_url": "https://boringtoolskit.com/color-tint-shade-calculator/", "category": "Colors & Design", "description": "Color tint shade calculator: lighten and darken a hex color in steps, generated locally.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "combinations-calculator", "name": "Combinations Calculator (nCr)", "canonical_url": "https://boringtoolskit.com/combinations-calculator/", "category": "Everyday Calculators", "description": "Calculate the number of combinations (nCr) of choosing r items from n, with the formula explained.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "August 2026", "related_urls": [ "/permutations-calculator/", "/order-of-operations-calculator/", "/general-scientific-calculator/" ], "answer": "Calculate the number of combinations (nCr) of choosing r items from n, with the formula explained.", "formula": "nCr = n! ÷ (r! × (n − r)!). The calculator evaluates it multiplicatively as c = c × (n − r + i) ÷ i for i = 1..r, which keeps intermediate values smaller than a raw factorial.", "example": "10 choose 3 = 120 distinct ways to select 3 items from 10.", "assumptions": [ "r must be between 0 and n, and n at least 1.", "Order does not matter (unordered selection).", "Result is rounded to the nearest integer." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculation methodology and verification standard", "url": "/methodology/" } ], "faqs": [ [ "What is a combination (nCr)?", "A combination counts the number of ways to choose r items from n where order does not matter. It is written nCr or 'n choose r'." ], [ "What is the combination formula?", "nCr = n! ÷ (r! × (n − r)!). The calculator uses the equivalent multiplicative form to avoid very large intermediate factorials." ], [ "When do I use combinations instead of permutations?", "Use combinations when order does not matter (like picking a committee). Use permutations when order does matter (like a ranked list)." ] ] }, { "slug": "combinations-permutations-calculator", "name": "Combinations and Permutations Calculator", "canonical_url": "https://boringtoolskit.com/combinations-permutations-calculator/", "category": "Statistics", "description": "Combinations and permutations calculator: count arrangements and selections with or without repetition.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "commission-calculator", "name": "Commission Calculator", "canonical_url": "https://boringtoolskit.com/commission-calculator/", "category": "Seller & Business", "description": "Calculate commission on sales using flat, threshold, or progressive tier rates. See total commission and a clear tier commission breakdown.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/etsy-fee-profit/", "/paycheck-calc/", "/percentage-calc/" ], "answer": "Calculate commission on sales using flat, threshold, or progressive tier rates. See total commission and a clear tier commission breakdown.", "formula": "Flat: commission = sales × rate. Threshold: rate applies only to sales above a floor. Tiered: multiple rates apply to brackets (e.g., 5% to $10k, 7% above). The tool reports commission, eligible sales, and a breakdown.", "example": "A flat 5% commission on $10,000 in sales = $500.", "assumptions": [ "Tiers apply marginally (each bracket at its own rate).", "Sales are net of returns.", "No draw, bonus, or chargeback adjustments." ], "sources": [ { "organization": "Wikipedia", "title": "Commission (remuneration)", "url": "https://en.wikipedia.org/wiki/Commission_(remuneration)" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate commission?", "Flat: sales × rate. 5% on $10,000 = $500." ], [ "What is a threshold plan?", "Commission starts only after sales exceed a floor — the rate applies to the excess or all sales depending on the plan." ], [ "What is a tiered plan?", "Rates increase with volume: 5% up to $10,000, 7% above — each bracket at its own rate." ], [ "What's the difference between marginal and cumulative tiers?", "Marginal applies each bracket's rate to that bracket only; cumulative may apply a single rate to everything once a tier is reached. Check your plan." ], [ "Do I get commission on returns?", "Usually no — chargebacks and returns are deducted from commission." ], [ "What is a draw?", "An advance against future commission — you pay it back from earnings." ], [ "How do I compare commission offers?", "Project realistic sales under each plan and compare the payouts — the calculator shows each structure's result." ], [ "What is a tiered commission?", "Higher rates apply to higher sales brackets — the calculator models the structure." ], [ "Is commission on gross or net?", "Depends on the plan — know whether returns and discounts reduce the base." ], [ "What is a fair commission rate?", "Varies by industry and margin; 3–10% is common for B2B, higher for high-margin sales." ] ] }, { "slug": "commute-cost-calculator", "name": "Commute Cost Calculator", "canonical_url": "https://boringtoolskit.com/commute-cost-calculator/", "category": "Travel", "description": "Commute cost calculator: monthly driving cost and time for a round trip.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "complementary-color-finder", "name": "Complementary Color Finder", "canonical_url": "https://boringtoolskit.com/complementary-color-finder/", "category": "Colors & Design", "description": "Complementary color finder: the exact opposite hue on the color wheel for any hex color.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "complex-number-calculator", "name": "Complex Number Calculator", "canonical_url": "https://boringtoolskit.com/complex-number-calculator/", "category": "Everyday Calculators", "description": "Complex number calculator: add, subtract, multiply complex numbers.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "compound-interest", "name": "Compound Interest Calculator", "canonical_url": "https://boringtoolskit.com/compound-interest/", "category": "Finance & Investing", "description": "Calculate compound interest with recurring contributions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/investment-return-calculator/", "/roth-ira-calculator/", "/retirement-planning-calculator/" ], "answer": "Calculate compound interest with recurring contributions.", "formula": "Future value = principal × (1 + rate/n)^(n×years), where n is the compounding frequency per year. Interest is earned on the principal AND on previously earned interest — the source of compounding growth.", "example": "A $10,000 investment at 7% compounded annually for 20 years grows to $10,000 × 1.07^20 ≈ $38,697 (vs $24,000 at simple interest).", "assumptions": [ "A constant annual return and fixed compounding frequency.", "No additional contributions, taxes, or fees.", "The projection is a mathematical estimate, not a guarantee." ], "sources": [ { "organization": "Investopedia", "title": "Compound Interest", "url": "https://www.investopedia.com/terms/c/compoundinterest.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is compound interest?", "Interest earned on both your principal and on previously earned interest, so growth accelerates over time." ], [ "How do I calculate future value?", "FV = principal × (1 + rate/n)^(n×years), where n is the compounding frequency per year." ], [ "What does compounding frequency mean?", "How often interest is added (annually, quarterly, monthly, daily). More frequent compounding produces slightly more growth." ], [ "Is the projected value guaranteed?", "No. It assumes a constant rate. Real returns vary with market performance, and fees/taxes reduce the actual amount." ], [ "Why does time matter so much?", "Compounding grows exponentially, so most of the final value comes from the later years. Starting earlier makes a dramatic difference even with the same rate." ], [ "What is simple vs compound interest?", "Simple interest is earned on the principal only; compound interest is earned on principal plus accumulated interest. The difference grows over time." ], [ "What rate should I use?", "Use a realistic, conservative expected return (historically ~7–9% nominal for broad stocks) and account for inflation if you want real growth." ] ] }, { "slug": "conception-calculator", "name": "Conception Calculator", "canonical_url": "https://boringtoolskit.com/conception-calculator/", "category": "Health", "description": "Conception calculator: conception date and fertility window from due date.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "concrete-calculator", "name": "Concrete Calculator", "canonical_url": "https://boringtoolskit.com/concrete-calculator/", "category": "Construction & Measurement", "description": "Estimate concrete volume, weight, and bags for a slab. Includes a built-in waste factor so you order enough the first time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/sonotube-concrete-column/", "/concrete-cost-per-square-foot/", "/mulch-soil-calculator/" ], "answer": "Estimate concrete volume, weight, and bags for a slab. Includes a built-in waste factor so you order enough the first time.", "formula": "Volume = length × width × (depth in inches ÷ 12) = cubic feet; cubic yards = cubic feet ÷ 27. Order volume = cubic yards × (1 + waste%).", "example": "A 10 × 10 ft slab at 4 in thick: 100 sq ft × 0.333 ft = 33.33 cu ft ≈ 1.235 cu yd. With 10% waste: ≈ 1.36 cu yd to order.", "assumptions": [ "The pour is a rectangular slab.", "Depth is uniform.", "Waste covers subgrade variation and spillage." ], "sources": [ { "organization": "Quikrete", "title": "Concrete Calculators", "url": "https://www.quikrete.com/calculator/main.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate concrete for a slab?", "Multiply length × width × thickness (in feet) to get cubic feet, then divide by 27 for cubic yards. A 10×10 ft slab at 4 in is about 1.24 cu yd." ], [ "How many cubic feet in a cubic yard?", "27 (3×3×3 ft). Ready-mix concrete is sold by the cubic yard." ], [ "How much concrete is in a bag?", "A 60 lb bag yields about 0.45 cu ft; an 80 lb bag about 0.6 cu ft. For a 1.36 cu yd slab you'd need roughly 80+ of the 60 lb bags." ], [ "Why add waste?", "Subgrade is rarely perfectly level, forms can flex, and concrete spills. 10% waste prevents running short — a cold joint mid-pour is a much bigger problem than a little extra concrete." ], [ "How do I convert inches to feet?", "Divide by 12: 4 in = 0.333 ft, 6 in = 0.5 ft." ], [ "Does this include rebar or wire mesh?", "No — reinforcement is planned separately based on the load and code." ], [ "How much does a cubic yard of concrete weigh?", "About 4,000 lb (2 tons) for standard concrete — plan access and formwork accordingly." ] ] }, { "slug": "concrete-cost-per-square-foot", "name": "Concrete Cost Per Square Foot Calculator", "canonical_url": "https://boringtoolskit.com/concrete-cost-per-square-foot/", "category": "Everyday Calculators", "description": "Estimate concrete cost per square foot and total for a slab from your own rate and waste.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/concrete-calculator/", "/sonotube-concrete-column/", "/square-footage-calculator/" ], "answer": "Estimate concrete cost per square foot and total for a slab from your own rate and waste.", "formula": "Total slab cost = area × rate per sq ft × (1 + waste%). The rate per square foot bundles material, labor, and finishing for the selected thickness.", "example": "A 400 sq ft slab at $8.00/sq ft with 10% waste: 400 × 8 × 1.10 = $3,520 estimated cost.", "assumptions": [ "The rate per square foot is user-entered from local pricing.", "Waste covers spillage and over-excavation.", "Excavation, sub-base, and permits are not included." ], "sources": [ { "organization": "Quikrete", "title": "Concrete Calculators", "url": "https://www.quikrete.com/calculator/main.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How much does a concrete slab cost per square foot?", "It varies widely by region, thickness, and finish — commonly in the $4–$12/sq ft range for material, labor, and finishing. Enter your local rate for a planning estimate." ], [ "What's included in the rate?", "Typically material, labor, forming, and a standard broom finish. Stamped, colored, or reinforced work costs more." ], [ "Why add waste?", "Slabs often need a little more concrete than the nominal volume — uneven grade, spilled concrete, and over-dig. 10% is a safe buffer." ], [ "Does this include excavation?", "No. Site prep, sub-base gravel, and permits are usually quoted separately." ], [ "How do I get an accurate rate?", "Ask 2–3 local contractors for per-square-foot pricing on a slab of your thickness and finish, then compare against this estimate." ], [ "Is a thicker slab always better?", "No — thicker costs more. 4 in is standard for patios and sidewalks; driveways often use 5–6 in. Match the thickness to the load." ], [ "Can I DIY it cheaper?", "Sometimes, for small slabs — but you carry the labor and risk. Ready-mix minimums and finishing skill matter. Use this to compare DIY vs contractor costs." ] ] }, { "slug": "conditional-probability-calculator", "name": "Conditional Probability Calculator", "canonical_url": "https://boringtoolskit.com/conditional-probability-calculator/", "category": "Statistics", "description": "Conditional probability calculator: P(A|B) from the intersection.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "cone-volume-calculator", "name": "Cone Volume Calculator", "canonical_url": "https://boringtoolskit.com/cone-volume-calculator/", "category": "Everyday Calculators", "description": "Cone volume calculator: volume from radius and height.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-27", "related_urls": [], "answer": "Cone volume calculator: volume from radius and height.", "formula": "Volume = (1/3) × π × r² × h, where r is base radius and h is height.", "example": "r = 3 m, h = 9 m: volume ≈ 84.82 m³.", "assumptions": [ "Standard geometric or arithmetic definitions apply.", "Inputs use the units you choose.", "Results are estimates, not professional advice." ], "sources": [ { "organization": "Standard mathematics definitions", "title": "Arithmetic and geometry formulas", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "confidence-interval-calculator", "name": "Confidence Interval Calculator", "canonical_url": "https://boringtoolskit.com/confidence-interval-calculator/", "category": "Everyday Calculators", "description": "Compute a confidence interval for a sample mean given size, std dev, and confidence level.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/sample-size-calculator/", "/standard-deviation-calculator/", "/mean-median-mode-calculator/" ], "answer": "Compute a confidence interval for a sample mean given size, std dev, and confidence level.", "formula": "Confidence interval = mean ± z* × (standard deviation ÷ √n). The tool uses z* = 1.645 for 90%, 1.96 for 95%, and 2.576 for 99% confidence, with standard error = sd ÷ √n and margin of error = z* × standard error.", "example": "A sample with mean 100, standard deviation 15, and n = 36 at 95% confidence: standard error = 15 ÷ 6 = 2.5, margin = 1.96 × 2.5 = 4.9, so the interval is [95.1, 104.9].", "assumptions": [ "The sample is drawn randomly and independently.", "The sampling distribution is roughly normal (large-sample z approach).", "The population standard deviation is approximated by the sample's." ], "sources": [ { "organization": "NIST/SEMATECH", "title": "e-Handbook of Statistical Methods — Confidence Intervals", "url": "https://www.itl.nist.gov/div898/handbook/eda/section3/eda352.htm" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a confidence interval?", "A range around a sample statistic that likely contains the population value. A 95% confidence interval means about 95% of similarly constructed intervals would contain the true mean." ], [ "How do I calculate it?", "CI = mean ± z* × (sd ÷ √n). For 95% confidence, z* = 1.96. The margin of error is z* times the standard error." ], [ "What is z*?", "The critical value from the standard normal distribution for the chosen confidence level: 1.645 (90%), 1.96 (95%), 2.576 (99%)." ], [ "What is standard error?", "The standard deviation of the sampling distribution: sd ÷ √n. It shrinks as the sample size grows, tightening the interval." ], [ "Why use t instead of z for small samples?", "With n under ~30, the t-distribution is wider than the normal, producing honest intervals. The z approach here is best for large samples." ], [ "Does a 95% interval mean 95% of data is inside?", "No. It means 95% of intervals from repeated sampling would contain the true population mean — a statement about the estimate, not about the data values." ], [ "How do I make the interval narrower?", "Increase the sample size or accept a lower confidence level. You can't fix a biased sample by widening the interval." ], [ "What is the 95% critical value?", "About 1.96 for large samples; 1.645 for 90% and 2.576 for 99%." ], [ "How does sample size affect it?", "Quadrupling the sample halves the interval width." ] ] }, { "slug": "contrast-ratio-calculator", "name": "Contrast Ratio Calculator (WCAG)", "canonical_url": "https://boringtoolskit.com/contrast-ratio-calculator/", "category": "Everyday Calculators", "description": "Check the contrast ratio between two colors and see whether it passes WCAG AA and AAA for normal and large text.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/color-picker/", "/hex-to-decimal/", "/percentage-calc/" ], "answer": "Check the contrast ratio between two colors and see whether it passes WCAG AA and AAA for normal and large text.", "formula": "WCAG contrast ratio = (L1 + 0.05) ÷ (L2 + 0.05), where L is relative luminance: 0.2126R + 0.7152G + 0.0722B with linearized channels.", "example": "White (#FFFFFF) on black (#000000) gives a 21:1 ratio — the maximum. Normal text needs ≥ 4.5:1 (WCAG AA).", "assumptions": [ "Hex colors are entered correctly.", "The WCAG 2.x luminance formula applies.", "Text size determines the applicable threshold." ], "sources": [ { "organization": "Wikipedia", "title": "Relative luminance", "url": "https://en.wikipedia.org/wiki/Relative_luminance" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a good contrast ratio?", "WCAG AA requires 4.5:1 for normal text and 3:1 for large text; AAA requires 7:1 for normal text. White on black is 21:1." ], [ "How is it calculated?", "Contrast = (L1 + 0.05) ÷ (L2 + 0.05) using relative luminance, where L = 0.2126R + 0.7152G + 0.0722B on linearized channels." ], [ "What colors pass?", "Dark text on light backgrounds usually passes; gray-on-white and yellow-on-white often fail." ], [ "Does large text need less contrast?", "Yes — 3:1 for large text (18pt+ or 14pt bold)." ], [ "Is this a legal requirement?", "WCAG compliance is required by law in many contexts (ADA, Section 508, EAA) and best practice everywhere." ], [ "Why is my ratio different from other tools?", "Small rounding differences exist; all should use the same WCAG formula. Check the luminance computation." ], [ "What about logos?", "Decorative and incidental text (logos, watermarks) is exempt from WCAG contrast requirements." ], [ "How is contrast ratio calculated?", "Relative luminance of the lighter color ÷ the darker, using the WCAG formula." ], [ "What colors fail?", "Light grays on white commonly fail — e.g., #999 on #FFF is about 2.8:1." ], [ "What does 21:1 mean?", "Pure black on pure white — the maximum possible contrast." ] ] }, { "slug": "cooking-time-calculator", "name": "Cooking Time Calculator", "canonical_url": "https://boringtoolskit.com/cooking-time-calculator/", "category": "Food & Cooking", "description": "Cooking time calculator: estimate oven or roasting time from weight and minutes-per-pound method.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "coordinate-converter", "name": "Coordinate Converter", "canonical_url": "https://boringtoolskit.com/coordinate-converter/", "category": "Geography", "description": "Coordinate converter: convert between decimal degrees and degrees/minutes/seconds.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "correlation-coefficient-calculator", "name": "Correlation Coefficient Calculator", "canonical_url": "https://boringtoolskit.com/correlation-coefficient-calculator/", "category": "Statistics", "description": "Correlation coefficient calculator: Pearson r between two paired data sets, with strength and direction.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "countdown-timer", "name": "Countdown Timer", "canonical_url": "https://boringtoolskit.com/countdown-timer/", "category": "Time & Work", "description": "Set a countdown and get notified when time is up.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/pomodoro-timer/", "/stopwatch/", "/world-clock/" ], "answer": "Set a countdown and get notified when time is up.", "formula": "Counts down from a set minutes/seconds value to zero, updating every second. The tool plays an alert and shows a done state when time expires.", "example": "A 5-minute countdown (5:00) ticks down to 0:00 and signals when finished.", "assumptions": [ "The tab stays open and visible during the countdown.", "The countdown is minutes-scale.", "The alert is audible in the browser." ], "sources": [ { "organization": "Wikipedia", "title": "Timer", "url": "https://en.wikipedia.org/wiki/Timer" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I set a countdown?", "Enter minutes and seconds, then start — the tool ticks down to zero and alerts you." ], [ "Can I use it for cooking?", "Yes — set the minutes for whatever's on the stove and keep the tab visible." ], [ "Why does it pause?", "Browsers throttle background tabs, which can pause timers. Keep the timer tab active for accuracy." ], [ "What's the difference from the Pomodoro timer?", "The Pomodoro timer runs structured work/break cycles; this is a plain countdown for any purpose." ], [ "Does it make a sound?", "The tool shows a done state and alert when time expires (browser sound depends on settings)." ], [ "Can I set seconds?", "Yes — both minutes and seconds are configurable." ], [ "How do I restart it?", "Reset and start again — useful for circuits and repeated intervals." ], [ "How does the countdown timer work?", "Set a duration, start, and the display counts down with an alert at zero." ], [ "Does it need an account?", "No — it runs locally in the browser." ], [ "Can I use it offline?", "Yes — the timer works without a connection once loaded." ], [ "What is a good focus duration?", "25 minutes is the classic Pomodoro block; any fixed duration works." ] ] }, { "slug": "countertop-calculator", "name": "Countertop Calculator", "canonical_url": "https://boringtoolskit.com/countertop-calculator/", "category": "Construction & Measurement", "description": "Countertop calculator: countertop cost from square feet.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "country-facts", "name": "Country Facts and Comparison", "canonical_url": "https://boringtoolskit.com/country-facts/", "category": "Text & Developer Tools", "description": "Browse country facts , capital, region, currency, languages, and flags , and compare two countries side by side.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/currency-conv/", "/world-clock/", "/timezone-converter/" ], "answer": "Browse country facts , capital, region, currency, languages, and flags , and compare two countries side by side.", "formula": "A static reference dataset of countries: name, code, capital, region, currency, languages, population, and area — formatted for comparison.", "example": "The United States: capital Washington, D.C., currency USD, population ≈ 331 million, area 9,833,517 km².", "assumptions": [ "Reference values are approximations.", "Currency codes use ISO 4217.", "Languages list the primary official languages." ], "sources": [ { "organization": "Wikipedia", "title": "Country", "url": "https://en.wikipedia.org/wiki/Country" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What facts does the tool show?", "Capital, currency, official languages, population, and area for each country." ], [ "How current are the figures?", "They're reference values — population estimates change with censuses. Verify for formal use." ], [ "Can I compare two countries?", "Yes — add countries and view them side by side." ], [ "What are currency codes?", "ISO 4217 three-letter codes: USD, EUR, GBP, JPY." ], [ "Does it cover every country?", "The dataset covers the major and common countries — not every nation." ], [ "Are languages complete lists?", "No — they list primary official languages, not every spoken language." ], [ "What is this used for?", "Travel planning, school projects, geography study, and market research." ] ] }, { "slug": "cpm-calculator", "name": "CPM Calculator", "canonical_url": "https://boringtoolskit.com/cpm-calculator/", "category": "Seller & Business", "description": "Calculate CPM, campaign cost, impressions, or estimated ad revenue from pageviews and RPM. Any two values solve the third.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/marketplace-ad-break-even-calculator/", "/customer-lifetime-value-calculator/", "/social-media-engagement-rate-calculator/" ], "answer": "Calculate CPM, campaign cost, impressions, or estimated ad revenue from pageviews and RPM. Any two values solve the third.", "formula": "CPM = cost ÷ impressions × 1,000. It's the price of 1,000 ad impressions — the standard metric for display and video campaigns.", "example": "$50 spent on 100,000 impressions: CPM = $0.50 per thousand.", "assumptions": [ "Impressions are delivered as reported.", "Spend is the full campaign cost.", "Comparisons use the same format and targeting." ], "sources": [ { "organization": "Wikipedia", "title": "Cost per impression", "url": "https://en.wikipedia.org/wiki/Cost_per_impression" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is CPM?", "Cost per mille — the price of 1,000 ad impressions: $50 ÷ 100,000 × 1,000 = $0.50." ], [ "How is it calculated?", "Ad spend ÷ impressions × 1,000." ], [ "What's a good CPM?", "It depends on the format — display runs from under $1 to several dollars; video and targeted campaigns can exceed $20." ], [ "Is low CPM always good?", "No — impressions that don't convert are wasted. Judge CPM with CTR and conversion data." ], [ "What's the difference from CPC?", "CPM charges per 1,000 impressions; CPC charges per click." ], [ "How do I compare placements?", "Same format and targeting, then look at effective CPM on viewable impressions." ], [ "Does this apply to social ads?", "Yes — platforms report CPM alongside CPC; it's the base cost of reach." ], [ "What does CPM stand for?", "Cost per mille — the cost per thousand impressions." ], [ "How do I calculate CPM?", "Cost ÷ impressions × 1,000: $50 ÷ 100,000 × 1,000 = $0.50." ], [ "Is CPM or CPC better?", "CPM for awareness, CPC/CPA for actions — they answer different questions." ], [ "What is a good CPM?", "It varies wildly by niche and market; compare against your revenue per thousand impressions." ] ] }, { "slug": "credit-card-payoff-calculator", "name": "Credit Card Payoff Calculator", "canonical_url": "https://boringtoolskit.com/credit-card-payoff-calculator/", "category": "Finance & Investing", "description": "Estimate credit-card payoff time and interest from balance, APR, and monthly payment.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/balance-transfer-savings-calculator/", "/compound-interest/", "/apr-effective-interest-calculator/" ], "answer": "Estimate credit-card payoff time and interest from balance, APR, and monthly payment.", "formula": "Simulates the balance month by month: balance += balance × APR ÷ 12 − payment. The tool reports months to payoff and total interest. Payment must exceed the first month's interest or it never pays off.", "example": "$5,000 at 22% APR with $200/month payments takes about 34 months and costs roughly $1,750 in interest.", "assumptions": [ "No new purchases are added.", "The payment stays constant.", "The APR is fixed." ], "sources": [ { "organization": "Wikipedia", "title": "Credit card", "url": "https://en.wikipedia.org/wiki/Credit_card" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How long will it take to pay off my card?", "The tool simulates the balance monthly: $5,000 at 22% with $200/mo takes about 34 months." ], [ "Why is my minimum payment barely helping?", "Each month, interest accrues on the balance — if the payment is close to the interest, almost nothing hits principal." ], [ "How much interest will I pay?", "The tool totals it: about $1,750 on the example above. Paying more monthly cuts it sharply." ], [ "What if my payment is less than the interest?", "The balance grows forever — the tool flags this." ], [ "Should I use the avalanche or snowball method?", "Avalanche (highest APR first) saves the most interest; snowball (smallest balance first) builds momentum. Both beat minimum payments." ], [ "Does this include new purchases?", "No — it assumes you stop adding to the balance. New charges extend payoff." ], [ "What about a balance transfer?", "Run the balance transfer calculator to compare a 0% promo against your current APR." ], [ "Is the minimum payment enough?", "Technically yes, practically no — minimums stretch payoff to decades." ], [ "Are balance transfers worth it?", "Compare the fee and post-promo rate against your current APR and payoff timeline." ] ] }, { "slug": "credit-utilization-calculator", "name": "Credit Utilization Calculator", "canonical_url": "https://boringtoolskit.com/credit-utilization-calculator/", "category": "Finance & Investing", "description": "Credit utilization calculator: credit score impact from balances vs limits.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "crochet-hook-converter", "name": "Crochet Hook Converter", "canonical_url": "https://boringtoolskit.com/crochet-hook-converter/", "category": "Converters", "description": "Crochet hook converter: US letters to millimeters.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "cross-product-calculator", "name": "Cross Product Calculator", "canonical_url": "https://boringtoolskit.com/cross-product-calculator/", "category": "Everyday Calculators", "description": "Cross product calculator: vector product of two 3D vectors.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "crown-molding-calculator", "name": "Crown Molding Calculator", "canonical_url": "https://boringtoolskit.com/crown-molding-calculator/", "category": "Construction & Measurement", "description": "Crown molding calculator: linear feet and boards needed for a room.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "crypto-calc", "name": "Crypto Profit Calculator", "canonical_url": "https://boringtoolskit.com/crypto-calc/", "category": "Finance & Investing", "description": "Calculate crypto profit and ROI with fees.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/stock-calc/", "/dca-investment-calculator/", "/investment-return-calculator/" ], "answer": "Calculate crypto profit and ROI with fees.", "formula": "Profit = (sell price − buy price) × amount − buy fees − sell fees. ROI = profit ÷ (buy price × amount + buy fee) × 100.", "example": "0.5 BTC bought at $60,000 and sold at $70,000: profit = 0.5 × $10,000 = $5,000 (before fees).", "assumptions": [ "Simple spot trades with no leverage.", "Fees are entered explicitly.", "No staking, airdrops, or other income is modeled." ], "sources": [ { "organization": "Wikipedia", "title": "Cryptocurrency", "url": "https://en.wikipedia.org/wiki/Cryptocurrency" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate crypto profit?", "Profit = (sell − buy) × amount − fees. 0.5 BTC from $60k to $70k = $5,000 before fees." ], [ "Does this work for any coin?", "Yes — enter any coin's buy/sell prices and amount; the math is the same." ], [ "Are fees included?", "Enter them — the tool subtracts buy and sell fees from profit." ], [ "What is ROI?", "Profit ÷ what you put in × 100 — the comparable return across trades of any size." ], [ "Do I owe taxes on crypto gains?", "In most jurisdictions, yes — often as capital gains. Check local rules; the tool doesn't model taxes." ], [ "Why is my actual profit different?", "Slippage and the bid-ask spread mean your real fill price differs from the quoted one." ], [ "What about staking rewards?", "The tool models spot trades only — add staking income separately to total returns." ], [ "Do exchange fees matter?", "Yes — 0.1% to 4% depending on venue; on large trades the difference is significant." ], [ "Is crypto taxable?", "Generally yes — sales are taxable events; keep your cost-basis records." ], [ "Is this a forecast?", "No — it calculates the profit on entered prices; it does not predict prices." ] ] }, { "slug": "csv-to-json", "name": "CSV to JSON Converter", "canonical_url": "https://boringtoolskit.com/csv-to-json/", "category": "Converters", "description": "Convert CSV to JSON instantly — paste comma or tab-separated data and get a clean JSON array of objects. Free, private, runs in your browser.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/base64-tool/", "/text-case/", "/keyword-density-calculator/" ], "answer": "Convert CSV to JSON instantly — paste comma or tab-separated data and get a clean JSON array of objects. Free, private, runs in your browser.", "formula": "Parses CSV rows: the first row becomes object keys; each subsequent row becomes an object mapping those keys to the row's values. Output is a JSON array of objects.", "example": "CSV 'name,age\\nAlice,30\\nBob,25' converts to [{\"name\":\"Alice\",\"age\":\"30\"},{\"name\":\"Bob\",\"age\":\"25\"}].", "assumptions": [ "The CSV has a header row.", "Fields with commas are properly quoted.", "Encoding is UTF-8." ], "sources": [ { "organization": "Wikipedia", "title": "Comma-separated values", "url": "https://en.wikipedia.org/wiki/Comma-separated_values" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I convert CSV to JSON?", "Paste your CSV with a header row — the first line becomes the keys and each following line becomes an object." ], [ "What is the output format?", "A JSON array of objects: [{\"name\":\"Alice\",\"age\":\"30\"}, …]." ], [ "Why are my numbers strings?", "CSV has no type information — everything parses as text. Convert numbers in your code or app as needed." ], [ "What if a value contains a comma?", "It must be quoted in the CSV (\"Doe, John\"). The parser handles standard quoted fields." ], [ "Does it run locally?", "Yes — the conversion happens entirely in your browser; nothing is uploaded." ], [ "How do I export CSV from Google Sheets?", "File → Download → Comma-separated values (.csv), then paste the contents." ], [ "Can I convert back (JSON to CSV)?", "This tool goes one direction; the CSV-to-JSON focus is importing data into code and APIs." ] ] }, { "slug": "currency-conv", "name": "Currency Converter", "canonical_url": "https://boringtoolskit.com/currency-conv/", "category": "Everyday Calculators", "description": "Free currency converter between 15+ major currencies — USD, EUR, GBP, JPY and more. Quick estimates with reference rates, no signup.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/country-facts/", "/percentage-calc/", "/sales-tax-vat-calculator/" ], "answer": "Free currency converter between 15+ major currencies — USD, EUR, GBP, JPY and more. Quick estimates with reference rates, no signup.", "formula": "Converts an amount between major currencies using reference exchange rates: converted = amount × (rate from → to).", "example": "$100 USD at 0.92 USD/EUR converts to €92.00.", "assumptions": [ "Reference rates are close to current mid-market.", "No transaction fees are modeled.", "The currencies are in the supported set." ], "sources": [ { "organization": "Wikipedia", "title": "Exchange rate", "url": "https://en.wikipedia.org/wiki/Exchange_rate" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I convert currency?", "Multiply the amount by the rate: $100 × 0.92 = €92." ], [ "Are these live rates?", "No — reference rates. Live rates move constantly; verify before transactions." ], [ "Why is my bank's rate different?", "Banks add a spread and fees on top of the mid-market rate." ], [ "Which currencies are supported?", "15+ majors: USD, EUR, GBP, JPY, CAD, AUD, CHF, CNY, INR, MXN, and more." ], [ "What is the mid-market rate?", "The real exchange rate between currencies, without bank margins — the baseline to compare offers." ], [ "How do I get the best rate?", "Compare the all-in cost (rate + fees) across transfer services — the cheapest isn't always the lowest-rate one." ], [ "Is this good for large transfers?", "Use it to estimate, but get live quotes for large amounts." ] ] }, { "slug": "curtain-length-calculator", "name": "Curtain Length Calculator", "canonical_url": "https://boringtoolskit.com/curtain-length-calculator/", "category": "Construction & Measurement", "description": "Curtain length calculator: panel length from window height.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "customer-lifetime-value-calculator", "name": "Customer Lifetime Value Calculator", "canonical_url": "https://boringtoolskit.com/customer-lifetime-value-calculator/", "category": "Seller & Business", "description": "Calculate gross-contribution customer lifetime value, implied lifetime, and a planning CAC ceiling from your inputs and LTV:CAC target.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/subscription-churn-impact-calculator/", "/break-even-units-calculator/", "/price-increase-impact-calculator/" ], "answer": "Calculate gross-contribution customer lifetime value, implied lifetime, and a planning CAC ceiling from your inputs and LTV:CAC target.", "formula": "Annual gross contribution = average order value × purchases per year × gross margin %. Customer lifetime = 1 ÷ annual churn rate. LTV = annual contribution × lifetime. Max acquisition cost = LTV ÷ target LTV:CAC ratio.", "example": "$50 order value, 4 purchases/year, 40% margin, 20% annual churn: annual contribution = $80, lifetime = 5 years, LTV = $400.", "assumptions": [ "Order value, frequency, and margin are stable.", "Churn is constant over the customer's life.", "No referral or expansion revenue is modeled." ], "sources": [ { "organization": "Wikipedia", "title": "Customer lifetime value", "url": "https://en.wikipedia.org/wiki/Customer_lifetime_value" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is customer lifetime value?", "The total profit a customer generates over their entire relationship with you — annual contribution × expected lifetime." ], [ "How do I calculate LTV?", "Annual contribution = AOV × purchases × margin; lifetime = 1 ÷ churn; LTV = annual × lifetime. $80 × 5 = $400." ], [ "What is churn?", "The annual rate at which customers stop buying — 20% churn means the average customer stays 5 years (1 ÷ 0.2)." ], [ "What is a good LTV:CAC ratio?", "3:1 or higher is a common healthy benchmark — you earn $3 for every $1 spent acquiring." ], [ "How much should I spend to acquire a customer?", "At a 3:1 target with $400 LTV, up to $133 on acquisition (the tool computes this from your target ratio)." ], [ "How do I improve LTV?", "Increase order value (upsells), frequency (retention programs), or margin; reduce churn." ], [ "Does LTV include referrals?", "No — the basic model counts the customer's own purchases. Referral value is a bonus on top." ] ] }, { "slug": "cycling-calories-calculator", "name": "Cycling Calories Calculator", "canonical_url": "https://boringtoolskit.com/cycling-calories-calculator/", "category": "Health", "description": "Cycling calories calculator: calories burned cycling by weight and time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "cycling-power-to-weight-calculator", "name": "Cycling Power to Weight Calculator", "canonical_url": "https://boringtoolskit.com/cycling-power-to-weight-calculator/", "category": "Sports", "description": "Cycling power-to-weight calculator: watts per kilogram for climbs and race grading.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "cylinder-volume-calculator", "name": "Cylinder Volume Calculator", "canonical_url": "https://boringtoolskit.com/cylinder-volume-calculator/", "category": "Physics", "description": "Cylinder volume calculator: volume of a cylinder from radius and height.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "dad-joke-generator", "name": "Dad Joke Generator", "canonical_url": "https://boringtoolskit.com/dad-joke-generator/", "category": "Generators", "description": "Generate groan-worthy dad jokes and one-liners by category — instantly, right in your browser.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "August 2026", "related_urls": [ "/random-quote-generator/", "/business-name-generator/", "/coin-flip/" ], "answer": "Generate groan-worthy dad jokes and one-liners by category — instantly, right in your browser.", "formula": "Jokes are drawn from category-specific pools and shuffled randomly. No external request is made — everything runs in your browser.", "example": "Select Food to get jokes like 'What do you call a sad cup of coffee? Depresso.'", "assumptions": [ "Generated output is a starting point, not final professional copy.", "Nothing you type leaves your browser.", "Results vary on each run because selection is random." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculation methodology and verification standard", "url": "/methodology/" } ], "faqs": [ [ "Where do the jokes come from?", "They're drawn from a built-in, curated list of classic one-liners." ], [ "Is anything sent to a server?", "No. The generator runs entirely in your browser." ], [ "Can I filter by type?", "Yes — choose a category like Food, Puns, or Halloween, or leave it on Random." ] ] }, { "slug": "daily-hydration-calculator", "name": "Daily Hydration Calculator", "canonical_url": "https://boringtoolskit.com/daily-hydration-calculator/", "category": "Everyday Calculators", "description": "Estimate your daily water intake from body weight, activity minutes, and climate temperature.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/bmr-tdee-calculator/", "/calorie-calc/", "/macro-planning-calculator/" ], "answer": "Estimate your daily water intake from body weight, activity minutes, and climate temperature.", "formula": "Baseline from body weight, adjusted for activity and climate: base ≈ weight × 0.5 oz, plus activity water, times a climate factor (0.9 cool – 1.45 very hot).", "example": "A 180 lb person in a mild climate with light activity starts from a ~90 oz baseline and adjusts up for heat and exercise.", "assumptions": [ "The weight-based formula is a reasonable baseline.", "Activity and climate adjustments are approximate.", "No medical conditions change the requirement." ], "sources": [ { "organization": "Wikipedia", "title": "Drinking water", "url": "https://en.wikipedia.org/wiki/Drinking_water" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How much water should I drink?", "Start from ~0.5 oz per pound of body weight, then adjust for activity and heat." ], [ "Is 8 glasses a day accurate?", "It's a rough average — real needs vary with size, activity, and climate." ], [ "How does exercise change it?", "Add water for sweat — roughly 12–16 oz per hour of moderate exercise." ], [ "Does hot weather matter?", "Yes — heat increases sweat; the climate factor raises the target." ], [ "Can I drink too much?", "Rarely, but endurance athletes can overhydrate — balance with electrolytes." ], [ "Does coffee count?", "Moderately — caffeine has a mild diuretic effect, so don't count it fully." ], [ "How do I know I'm hydrated?", "Thirst and pale-yellow urine are practical daily indicators." ], [ "Does exercise change it?", "Yes — add roughly 12–16 oz per hour of moderate exercise." ] ] }, { "slug": "data-storage-converter", "name": "Data Storage Converter", "canonical_url": "https://boringtoolskit.com/data-storage-converter/", "category": "Converters", "description": "Data storage converter: bytes, KB, MB, GB, TB (binary 1024 base).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "data-transfer-rate-calculator", "name": "Data Transfer Rate Calculator", "canonical_url": "https://boringtoolskit.com/data-transfer-rate-calculator/", "category": "Everyday Calculators", "description": "Estimate how long a file takes to transfer at a given speed, or the effective rate given size and time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/battery-runtime-calculator/", "/electricity-cost-calculator/", "/data-transfer-rate-calculator/" ], "answer": "Estimate how long a file takes to transfer at a given speed, or the effective rate given size and time.", "formula": "Transfer time = file size (GB) × 8,000 ÷ speed (Mbps). Result in seconds, minutes, or hours. It converts between bits and bytes (8 bits per byte).", "example": "A 10 GB file at 100 Mbps: 10 × 8,000 ÷ 100 = 800 seconds ≈ 13.3 minutes.", "assumptions": [ "The connection runs at the entered speed.", "8 bits = 1 byte.", "No overhead or throttling is modeled." ], "sources": [ { "organization": "Wikipedia", "title": "Data-rate units", "url": "https://en.wikipedia.org/wiki/Data-rate_units" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate transfer time?", "Size × 8,000 ÷ speed: 10 GB × 8000 ÷ 100 = 800 seconds." ], [ "Why do I multiply by 8,000?", "GB → megabits: 1 GB = 8,000 megabits (8 bits per byte × 1,000)." ], [ "Why is my real speed slower?", "Advertised speeds are theoretical — Wi-Fi, network congestion, and server limits cut real throughput." ], [ "What speed do I need for a 1 GB download?", "At 100 Mbps: 80 seconds. At 10 Mbps: 13+ minutes." ], [ "Is this for uploads too?", "Yes — use your upload speed if that's the limiting link." ], [ "What's the difference between MB and Mb?", "MB = megabytes (file size); Mb = megabits (speed). 8 Mb = 1 MB." ], [ "How accurate is the estimate?", "It's best-case at the entered speed — use 70–80% of plan speed for realism." ], [ "Why multiply by 8,000?", "GB to megabits: 8 bits per byte × 1,000." ], [ "Is my real speed the same as advertised?", "No — typically 50–90% of plan speed due to Wi-Fi and congestion." ], [ "Do uploads transfer at the same speed?", "Usually slower — check your plan's upload rate." ] ] }, { "slug": "date-calculator-workspace", "name": "Date Calculator Workspace", "canonical_url": "https://boringtoolskit.com/date-calculator-workspace/", "category": "Time & Work", "description": "Compare dates or add and subtract calendar units with leap-day and month-end handling.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/date-difference-calculator/", "/business-days-calculator/", "/age-calculator/" ], "answer": "Compare dates or add and subtract calendar units with leap-day and month-end handling.", "formula": "Adds or subtracts days, weeks, months, and years to a date, and finds the difference between two dates. The tool reports the result weekday and handles month-length and leap-year boundaries.", "example": "January 15, 2026 plus 45 days = March 1, 2026 (a Sunday).", "assumptions": [ "The Gregorian calendar applies.", "Dates are interpreted at midnight.", "Month-end clamping follows calendar rules." ], "sources": [ { "organization": "Wikipedia", "title": "Gregorian calendar", "url": "https://en.wikipedia.org/wiki/Gregorian_calendar" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I add days to a date?", "Use add mode: January 15, 2026 + 45 days = March 1, 2026." ], [ "What happens adding a month to Jan 31?", "It clamps to the month end: Feb 28 (or 29 in a leap year) — the calendar rule, not an error." ], [ "How do I find the span between dates?", "Use span mode and pick both dates — the tool reports the difference in days, weeks, and months." ], [ "Does it show the weekday?", "Yes — the result includes which day of the week it falls on." ], [ "Does it handle leap years?", "Yes — February 29 is counted when it falls in the span." ], [ "Can I subtract intervals?", "Yes — subtract mode works for any interval, e.g., a 90-day lookback." ], [ "Is this the same as the business days calculator?", "No — this workspace counts all calendar days; business days exclude weekends." ] ] }, { "slug": "date-difference-calculator", "name": "Date Difference Calculator", "canonical_url": "https://boringtoolskit.com/date-difference-calculator/", "category": "Time & Work", "description": "Calculate elapsed years, months, weeks, and days between two dates.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/business-days-calculator/", "/date-calculator-workspace/", "/age-calculator/" ], "answer": "Calculate elapsed years, months, weeks, and days between two dates.", "formula": "Days = |end date − start date| in whole days, from local midnight. The tool also reports the difference in weeks, months, and years.", "example": "January 1 to March 1, 2026 is 59 days — about 8.4 weeks and roughly 2 months.", "assumptions": [ "Both dates are interpreted at local midnight.", "The calendar (Gregorian) is the reference.", "The difference is absolute (order doesn't matter)." ], "sources": [ { "organization": "Wikipedia", "title": "Gregorian calendar", "url": "https://en.wikipedia.org/wiki/Gregorian_calendar" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate the difference between dates?", "Subtract the earlier from the later: Jan 1 to Mar 1, 2026 = 59 days." ], [ "Does it count the start and end days?", "It counts whole days between the dates — the tool's convention is consistent, so use it the same way each time." ], [ "How many weeks is that?", "Days ÷ 7: 59 days ≈ 8.4 weeks." ], [ "Does it handle leap years?", "Yes — February 29 is counted when it falls between the dates." ], [ "Why are months approximate?", "Months have 28–31 days, so 'months' is an estimate unless you count calendar month boundaries exactly." ], [ "Can I count business days instead?", "Use the business days calculator for weekday-only counts." ], [ "How do I calculate a duration in years?", "Days ÷ 365.25 approximates calendar years including leap years." ] ] }, { "slug": "day-of-the-week-calculator", "name": "Day of the Week Calculator", "canonical_url": "https://boringtoolskit.com/day-of-the-week-calculator/", "category": "Everyday Calculators", "description": "Day of the week calculator: what weekday was any date, plus week number and day of year.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "days-between-dates-calculator", "name": "Days Between Dates Calculator", "canonical_url": "https://boringtoolskit.com/days-between-dates-calculator/", "category": "Everyday Calculators", "description": "Find the number of days, weeks, and weekdays between two dates.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/business-days-calculator/", "/date-difference-calculator/", "/hours-minutes-calculator/" ], "answer": "Find the number of days, weeks, and weekdays between two dates.", "formula": "Days = (end date − start date) ÷ 86,400,000 ms per day, computed on calendar dates at midnight. Weeks = days ÷ 7. Weekday count iterates the calendar days between the dates, excluding weekends.", "example": "From January 1 to February 1, 2026: 31 days = 4.4 weeks.", "assumptions": [ "Both dates are interpreted at local midnight.", "The end date is later than the start date.", "Weekday count excludes Saturdays and Sundays only." ], "sources": [ { "organization": "CalculatorSoup", "title": "Date Difference Calculator", "url": "https://www.calculatorsoup.com/calculators/time/date-difference-calculator.php" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I count days between two dates?", "Subtract the earlier date from the later one in calendar terms — the tool does this exactly. Jan 1 to Feb 1 is 31 days." ], [ "What is the difference between calendar and business days?", "Calendar days count every day; business days exclude weekends (and often holidays). The tool shows calendar days plus a weekday count." ], [ "Is the end date included?", "The tool counts the gap between the dates (end minus start). If you need inclusive counting, add one." ], [ "Why does the tool reject equal dates?", "The end date must be after the start for a positive gap. If they're equal, the gap is zero." ], [ "How many weekdays are between two dates?", "Count the days that fall on Monday–Friday. The tool iterates the calendar to compute this." ], [ "Does this account for holidays?", "No — holidays are jurisdiction-specific. Subtract them manually for business timelines." ], [ "What about leap years?", "The calendar handles leap years automatically — Feb 29 is counted when it falls between the dates." ] ] }, { "slug": "db-to-volume-calculator", "name": "dB to Volume Ratio Calculator", "canonical_url": "https://boringtoolskit.com/db-to-volume-calculator/", "category": "Music & Audio", "description": "Convert decibels to power or amplitude ratios for audio gain changes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/frequency-to-note-calculator/", "/scale-finder-calculator/", "/audio-time-stretch-calculator/" ], "answer": "Convert decibels to power or amplitude ratios for audio gain changes.", "formula": "Power ratio = 10^(dB ÷ 10). Amplitude ratio = 10^(dB ÷ 20). Percent change = (ratio − 1) × 100.", "example": "A +6 dB power change: ratio = 10^(6/10) ≈ 3.98, a ~298% increase. A +6 dB amplitude change: ratio = 10^(6/20) ≈ 2.0, a 100% increase.", "assumptions": [ "A change of 10 dB is a 10× power ratio and a ~3.16× amplitude ratio.", "The dB value is a relative change, not an absolute level.", "Power and amplitude use different factors (10 vs 20)." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "dca-investment-calculator", "name": "DCA Investment Calculator", "canonical_url": "https://boringtoolskit.com/dca-investment-calculator/", "category": "Finance & Investing", "description": "Estimate recurring-investment growth, contributions, and gains using monthly compounding.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/investment-return-calculator/", "/dividend-reinvestment-calculator/", "/compound-interest/" ], "answer": "Estimate recurring-investment growth, contributions, and gains using monthly compounding.", "formula": "Simulates monthly contributions compounding: each month, new value = (current value + contribution) × (1 + monthly return). Monthly return = annual return ÷ 12.", "example": "Investing $500/month for 10 years at 7% annual return grows to about $87,000 — with only $60,000 contributed.", "assumptions": [ "Contributions are made monthly at the entered amount.", "Returns compound monthly at the constant annual rate.", "No withdrawals are made." ], "sources": [ { "organization": "Wikipedia", "title": "Dollar cost averaging", "url": "https://en.wikipedia.org/wiki/Dollar_cost_averaging" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is dollar-cost averaging?", "Investing a fixed amount on a regular schedule regardless of price — buying more when cheap, less when expensive." ], [ "How much does $500/month become?", "At 7% over 10 years, about $87,000 from $60,000 contributed — the rest is compounding." ], [ "Why is DCA better than lump sum?", "It removes timing risk and emotion. Historically, lump sum often outperforms, but DCA is easier to sustain and psychologically safer." ], [ "What return should I assume?", "Conservative planning uses 4–7% for broad index funds. Past performance isn't a guarantee." ], [ "Does it work in down markets?", "Yes — that's the point: lower prices buy more shares, which pays off when the market recovers." ], [ "How do I start?", "Automate a monthly transfer to an index fund or ETF and increase it with raises." ], [ "Is this financial advice?", "No — the calculator projects math under your assumptions. Decisions are yours." ], [ "How does dollar-cost averaging work?", "Invest a fixed amount on a schedule, buying more shares when prices are low and fewer when high." ], [ "Does lump sum beat DCA?", "On average, lump sum wins about two-thirds of the time — but DCA protects against regret and panic selling." ], [ "How much of the final value is my contributions?", "Early, most; over decades, growth dominates — the calculator separates both." ] ] }, { "slug": "debt-avalanche-calculator", "name": "Debt Avalanche Calculator", "canonical_url": "https://boringtoolskit.com/debt-avalanche-calculator/", "category": "Finance & Investing", "description": "Debt avalanche calculator: pay off highest-interest debt first to minimize interest.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "debt-consolidation-calculator", "name": "Debt Consolidation Calculator", "canonical_url": "https://boringtoolskit.com/debt-consolidation-calculator/", "category": "Finance & Investing", "description": "Debt consolidation calculator: current debts vs one consolidation loan.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "debt-free-date-calculator", "name": "Debt Free Date Calculator", "canonical_url": "https://boringtoolskit.com/debt-free-date-calculator/", "category": "Finance & Investing", "description": "Debt free date calculator: payoff timeline at a monthly payment.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "debt-payoff", "name": "Debt Payoff Calculator", "canonical_url": "https://boringtoolskit.com/debt-payoff/", "category": "Finance & Investing", "description": "Estimate one debt's payoff timeline and compare a fixed payment with an extra-payment scenario.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/student-loan-payoff/", "/loan-comparison-calculator/", "/balance-transfer-savings-calculator/" ], "answer": "Estimate one debt's payoff timeline and compare a fixed payment with an extra-payment scenario.", "formula": "Debt payoff simulates applying a monthly payment (plus any extra) to a balance, accruing interest at the monthly rate. It finds the number of months to clear the balance and the total interest paid — showing how an extra payment shortens the term.", "example": "A $8,000 credit card balance at 18% with a $250 monthly payment takes about 43 months and costs roughly $2,400 in interest; adding $100 extra cuts it to ~28 months and saves ~$1,000.", "assumptions": [ "A fixed APR applied monthly (APR ÷ 12) on the outstanding balance.", "Payments are consistent and you make no new charges.", "The model uses monthly compounding on the remaining balance." ], "sources": [ { "organization": "Investopedia", "title": "Debt Payoff", "url": "https://www.investopedia.com/terms/d/debt-payoff.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I pay off debt faster?", "Pay more than the minimum, or make extra principal payments. The higher the payment, the less interest accrues and the sooner the debt is gone." ], [ "Should I pay the highest or smallest balance first?", "Avalanche (highest APR first) saves the most in interest; snowball (smallest first) builds momentum. Both work — pick what keeps you motivated." ], [ "Why is the interest so high on credit cards?", "Credit card APRs are high (often 15–25%) and the interest compounds monthly, so carrying a balance is expensive. Paying above the minimum is key." ], [ "How much interest will I pay?", "It depends on the balance, APR, and payment. The calculator simulates it exactly — a higher or longer payment changes the total substantially." ], [ "Is a balance transfer worth it?", "Maybe, if the fee is less than the interest you'd save and you can pay it off before the intro rate ends. The calculator can compare the cost." ], [ "What APR should I use?", "Your card's current APR, which is on your statement. Variable rates change, so re-check periodically." ], [ "What happens if I only pay the minimum?", "The term stretches out and total interest multiplies. Minimums are structured to keep you in debt — always pay more if you can." ] ] }, { "slug": "debt-service-coverage-ratio-calculator", "name": "DSCR Calculator", "canonical_url": "https://boringtoolskit.com/debt-service-coverage-ratio-calculator/", "category": "Finance & Investing", "description": "Calculate the debt service coverage ratio (DSCR) for a rental property. Enter net operating income and annual debt service.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/net-operating-income-calculator/", "/loan-to-value-calculator/", "/break-even-ratio-calculator/" ], "answer": "Calculate the debt service coverage ratio (DSCR) for a rental property. Enter net operating income and annual debt service.", "formula": "Debt-service coverage ratio (DSCR) = net operating income ÷ annual debt service. A DSCR above 1.0 means the property generates enough income to cover its loan payment; most lenders prefer 1.25 or higher.", "example": "NOI of $60,000 ÷ annual debt service of $45,000 = DSCR 1.33, which is comfortable for most lenders.", "assumptions": [ "NOI excludes debt service, taxes, and capex.", "Annual debt service is the full monthly P&I payment × 12.", "Lenders typically want ≥ 1.25; some accept 1.1 for strong borrowers." ], "sources": [ { "organization": "Investopedia", "title": "Debt Service Coverage Ratio", "url": "https://www.investopedia.com/terms/d/dscr.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a good DSCR?", "Most lenders want 1.25 or higher (1.25× coverage). Some accept 1.1 for strong borrowers or 1.2 for residential. Below 1.0 means the property doesn't fully cover its debt." ], [ "How do I calculate DSCR?", "DSCR = net operating income ÷ annual debt service (monthly mortgage × 12)." ], [ "What does a DSCR of 1.0 mean?", "The property earns exactly enough to cover its loan payment — no cushion for vacancy or repairs." ], [ "Does DSCR include taxes?", "No. DSCR is based on NOI, which excludes income tax. It covers operating income vs debt service." ], [ "Why do lenders care about DSCR?", "It measures the risk of default. A higher cushion means more likely the loan is repaid even if income dips." ], [ "Can a property be cash-flow positive but have a low DSCR?", "Yes — a high down payment lowers debt service, so DSCR may look strong even if monthly cash flow is modest. Check both." ], [ "How do vacancy and repairs affect DSCR?", "A vacancy or big repair lowers NOI, which lowers DSCR. Stress-test your DSCR with a vacancy allowance." ] ] }, { "slug": "debt-snowball-calculator", "name": "Debt Snowball Calculator", "canonical_url": "https://boringtoolskit.com/debt-snowball-calculator/", "category": "Finance & Investing", "description": "Debt snowball calculator: pay off debts smallest-first with extra payments.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "debt-to-income-ratio-calculator", "name": "Debt-to-Income Ratio Calculator", "canonical_url": "https://boringtoolskit.com/debt-to-income-ratio-calculator/", "category": "Finance & Investing", "description": "Calculate your front-end and back-end DTI ratio from monthly income, housing, and debt payments. Free, private, no signup.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/mortgage-afford/", "/loan-comparison-calculator/", "/debt-payoff/" ], "answer": "Calculate your front-end and back-end DTI ratio from monthly income, housing, and debt payments. Free, private, no signup.", "formula": "Debt-to-income (DTI) ratio = total monthly debt payments ÷ gross monthly income × 100. The calculator sums housing, car, student, credit-card, and other debts and divides by gross monthly income.", "example": "A borrower with $7,500 gross monthly income and $2,500 in total monthly debt payments has a DTI of $2,500 ÷ $7,500 = 33.3%.", "assumptions": [ "DTI uses gross monthly income.", "Debt payments are minimum required monthly payments.", "The ratio is back-end (all debts) unless you focus on housing only." ], "sources": [ { "organization": "Investopedia", "title": "Debt-to-Income Ratio", "url": "https://www.investopedia.com/terms/d/debt-to-income-ratio.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a good DTI?", "Most lenders want a back-end DTI at or below 36%, and many prefer under 43% for approved mortgages. A lower DTI means more borrowing room and better terms." ], [ "How do I calculate DTI?", "DTI = total monthly debt payments ÷ gross monthly income × 100." ], [ "What's the difference between front-end and back-end DTI?", "Front-end is housing costs (mortgage, taxes, insurance) only. Back-end includes all debts (car, student, credit cards). Lenders check both." ], [ "How do I lower my DTI?", "Pay down debt (reduces the numerator) or increase income (raises the denominator). Both improve the ratio." ], [ "Does DTI use gross or net income?", "Gross (pre-tax) monthly income. Lenders use your pre-tax income when calculating DTI." ], [ "What is the max DTI for a mortgage?", "Conventional loans typically allow up to 43% back-end, though many lenders prefer 36% or lower for the best terms and rates." ], [ "Is DTI the only factor in getting a loan?", "No. Credit score, employment history, cash reserves, and the down payment all matter. DTI is a key gate but not the only one." ] ] }, { "slug": "decimal-to-fraction-calculator", "name": "Decimal to Fraction Calculator", "canonical_url": "https://boringtoolskit.com/decimal-to-fraction-calculator/", "category": "School & Education", "description": "Decimal to fraction calculator: convert a decimal to a simplified fraction.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "deck-board-calculator", "name": "Deck Board Calculator", "canonical_url": "https://boringtoolskit.com/deck-board-calculator/", "category": "Construction & Measurement", "description": "Deck board calculator: decking boards for a deck area.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "deck-stain-calculator", "name": "Deck Stain Calculator", "canonical_url": "https://boringtoolskit.com/deck-stain-calculator/", "category": "Construction & Measurement", "description": "Deck stain calculator: gallons of stain from deck area and coats, with coverage assumptions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "decking-calculator", "name": "Decking Calculator", "canonical_url": "https://boringtoolskit.com/decking-calculator/", "category": "Construction & Measurement", "description": "Estimate deck boards and linear footage using deck dimensions, board width, gap, and waste.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/fence-material-calculator/", "/square-footage-calculator/", "/sonotube-concrete-column/" ], "answer": "Estimate deck boards and linear footage using deck dimensions, board width, gap, and waste.", "formula": "Courses = ceil((deck width × 12) ÷ (board width + gap)). Linear feet = courses × deck length. With waste = linear feet × (1 + waste%). Boards = ceil(with waste ÷ board length).", "example": "A 12 ft wide × 16 ft long deck with 5.5 in boards and 0.25 in gaps: courses = ceil(144 ÷ 5.75) = 26, linear feet = 26 × 16 = 416. With 10% waste: 457.6 ft, requiring ceil(457.6 ÷ 16) = 29 sixteen-foot boards.", "assumptions": [ "The deck surface is a rectangle laid straight.", "Board width and gap are in inches.", "Boards are purchased in the entered length." ], "sources": [ { "organization": "Wikipedia", "title": "Deck (building)", "url": "https://en.wikipedia.org/wiki/Deck_(building)" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate how many deck boards I need?", "Divide the deck width (in inches) by the board width plus gap to get the number of courses, multiply by the deck length for linear feet, add waste, and divide by the board length." ], [ "What is a board course?", "One row of deck boards running across the deck. A 12 ft deck with 5.5 in boards needs about 26 courses." ], [ "What gap should I leave between boards?", "About 1/8–1/4 inch for wood (lets water drain and boards expand). Composite boards have manufacturer-specified spacing." ], [ "How much waste should I add?", "10% is standard for straight layouts — it covers cuts at the ends, boards with defects, and mistakes." ], [ "Do I need boards for the frame too?", "No — this calculator estimates the surface boards only. Joists, beams, posts, and fasteners are planned separately." ], [ "Why is board width important?", "The actual (not nominal) width determines how many courses fit across the deck. Check the product spec before calculating." ], [ "What about diagonal decks?", "Diagonal layouts use more boards (roughly 15–20% more) because of angled cuts. Add extra waste." ], [ "How many deck boards do I need?", "Divide the deck area by the usable board width and add 10–15% for waste." ], [ "How much waste should I plan for?", "10% for straight decks; 15% or more for diagonal patterns and curves." ], [ "Does board width matter?", "Yes — wider boards cover more area per board, so the count changes with width and spacing." ], [ "Does the calculator include joists and fasteners?", "It estimates decking and framing; add hardware and fasteners at local prices." ] ] }, { "slug": "degree-progress-calculator", "name": "Degree Progress Calculator", "canonical_url": "https://boringtoolskit.com/degree-progress-calculator/", "category": "School & Education", "description": "Degree progress calculator: completion percentage, remaining credits, and terms to finish.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "dehumidifier-sizing-calculator", "name": "Dehumidifier Sizing Calculator", "canonical_url": "https://boringtoolskit.com/dehumidifier-sizing-calculator/", "category": "Energy & Electrical", "description": "Dehumidifier sizing calculator: pints per day by room size and dampness.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "delay-time-calculator", "name": "Delay Time Calculator", "canonical_url": "https://boringtoolskit.com/delay-time-calculator/", "category": "Music & Audio", "description": "Delay time calculator: note-based delay milliseconds from BPM for quarter, eighth, dotted, and triplet notes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "density-calculator", "name": "Density Calculator", "canonical_url": "https://boringtoolskit.com/density-calculator/", "category": "Physics", "description": "Calculate density from mass and volume (ρ = m/V) in kg/m³ and g/cm³.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/pressure-calculator/", "/thermal-equilibrium-calculator/", "/molar-mass-calculator/" ], "answer": "Calculate density from mass and volume (ρ = m/V) in kg/m³ and g/cm³.", "formula": "Density (ρ) = mass ÷ volume. Units: kg/m³. Conversion: g/cm³ = kg/m³ ÷ 1000.", "example": "A 200 kg object with 0.5 m³ volume: ρ = 200 ÷ 0.5 = 400 kg/m³ = 0.4 g/cm³.", "assumptions": [ "Mass is in kilograms and volume in cubic meters.", "The material is assumed homogeneous.", "Positive values are required for both inputs." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "depop-fee-calculator", "name": "Depop Fee Calculator", "canonical_url": "https://boringtoolskit.com/depop-fee-calculator/", "category": "Seller & Business", "description": "Depop fee calculator: the 10% selling fee plus payment processing and your net.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "depreciation-calculator", "name": "Depreciation Calculator", "canonical_url": "https://boringtoolskit.com/depreciation-calculator/", "category": "Everyday Calculators", "description": "Estimate straight-line or declining-balance depreciation over an asset's life.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/irr-calculator/", "/present-value-calculator/", "/inflation-impact-calculator/" ], "answer": "Estimate straight-line or declining-balance depreciation over an asset's life.", "formula": "Straight line: annual depreciation = (cost − salvage) ÷ useful life. Declining balance (double): first-year depreciation = cost × (2 ÷ life); the tool reports the first-year amount and ending book value for the selected method.", "example": "A $50,000 asset with $5,000 salvage value and a 5-year life: straight-line annual depreciation = ($50,000 − $5,000) ÷ 5 = $9,000. Declining balance first year = $50,000 × (2 ÷ 5) = $20,000.", "assumptions": [ "Salvage value is the estimated resale value at the end of life.", "Straight line spreads the depreciable base evenly.", "Declining balance reports the first-year amount using a double-declining rate." ], "sources": [ { "organization": "Investopedia", "title": "Depreciation", "url": "https://www.investopedia.com/terms/d/depreciation.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is depreciation?", "Depreciation is the accounting practice of spreading an asset's cost over its useful life, reflecting that equipment, vehicles, and buildings wear out and lose value over time." ], [ "What is the straight-line method?", "It deducts an equal amount each year: (cost − salvage value) ÷ useful life. Simple and predictable — the most common method for book accounting." ], [ "What is the declining-balance method?", "An accelerated method that applies a fixed rate (here double-declining: 2 ÷ life) to the remaining book value, producing larger deductions in early years." ], [ "What is salvage value?", "The estimated resale value of the asset at the end of its useful life. It caps how much can be depreciated: the depreciable base is cost minus salvage." ], [ "Does this match tax depreciation?", "Not exactly. Tax depreciation often uses MACRS or section 179 rules with specific class lives and conventions. This calculator is for planning and book estimates, not tax filing." ], [ "What is book value?", "Book value = original cost − accumulated depreciation. It's what the asset is carried at on the balance sheet, not necessarily its market value." ], [ "Which method should I use?", "Straight line if you want even expenses; declining balance if you want larger early deductions (common when an asset loses value fastest early on). Check what your tax rules allow." ], [ "How do I calculate straight-line depreciation?", "(Cost − salvage) ÷ useful life." ], [ "What is accelerated depreciation?", "Front-loaded deductions like double-declining or MACRS that defer tax." ], [ "Does depreciation affect cash?", "No — it is an allocation that reduces taxable income, not a cash expense." ], [ "What life should I use?", "The tax recovery period (MACRS) for taxes; the accounting life for books." ] ] }, { "slug": "depth-of-field-calculator", "name": "Depth of Field Calculator", "canonical_url": "https://boringtoolskit.com/depth-of-field-calculator/", "category": "Photo & Video", "description": "Depth of field calculator: estimate near and far focus limits from focal length, aperture, subject distance, and circle of confusion.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "dice-roller", "name": "Dice Roller", "canonical_url": "https://boringtoolskit.com/dice-roller/", "category": "Everyday Calculators", "description": "Roll 1–10 selectable D4, D6, D8, D10, D12, or D20 dice using unbiased local browser randomness.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/coin-flip/", "/random-number-generator/", "/random-name-picker/" ], "answer": "Roll 1–10 selectable D4, D6, D8, D10, D12, or D20 dice using unbiased local browser randomness.", "formula": "Simulates rolls of standard dice (D4, D6, D8, D10, D12, D20) with a uniform random generator, summing multiple dice.", "example": "Rolling 2D6 produces totals from 2 to 12, with 7 being the most likely.", "assumptions": [ "Dice are fair (uniform distribution).", "Each roll is independent.", "Standard die types are sufficient." ], "sources": [ { "organization": "Wikipedia", "title": "Dice", "url": "https://en.wikipedia.org/wiki/Dice" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How does the dice roller work?", "It generates uniform random rolls for standard dice — D4 through D20 — and totals them." ], [ "What dice does it support?", "D4, D6, D8, D10, D12, and D20 — the standard tabletop set." ], [ "Why is 7 the most common 2D6 total?", "More combinations sum to 7 than any other total — the distribution forms a bell curve." ], [ "Are the rolls fair?", "Each face is equally likely, generated with a uniform pseudorandom source." ], [ "Can I roll with advantage?", "Not directly — roll twice and take the higher yourself." ], [ "What is a D20 used for?", "The classic d20 is the core die for checks and attacks in many RPGs." ], [ "How many dice can I roll?", "Up to 10 at once — the tool sums them." ] ] }, { "slug": "diesel-vs-gas-calculator", "name": "Diesel vs Gas Calculator", "canonical_url": "https://boringtoolskit.com/diesel-vs-gas-calculator/", "category": "Vehicles", "description": "Diesel vs gas calculator: per-mile fuel cost comparison.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "dilution-calculator", "name": "Dilution Calculator (C1V1=C2V2)", "canonical_url": "https://boringtoolskit.com/dilution-calculator/", "category": "Chemistry", "description": "Solve dilution problems using C1V1 = C2V2 to find stock or final volumes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/serial-dilution-calculator/", "/c1v1-c2v2-calculator/", "/molarity-calculator/" ], "answer": "Solve dilution problems using C1V1 = C2V2 to find stock or final volumes.", "formula": "C₁V₁ = C₂V₂. Leave one of C₁, V₁, C₂, V₂ blank and the tool solves for it.", "example": "To make 500 mL of 0.1 M from a 2.0 M stock: V₁ = (0.1 × 500) ÷ 2.0 = 25 mL of stock, then dilute to 500 mL.", "assumptions": [ "Fill exactly three of the four variables; the fourth is solved.", "Volume units must be consistent across V₁ and V₂.", "Dilution assumes the solute is the limiting component and volumes are additive." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "discount-percent-off-calculator", "name": "Percent Off Calculator", "canonical_url": "https://boringtoolskit.com/discount-percent-off-calculator/", "category": "Seller & Business", "description": "Calculate stacked percent-off discounts, apply a coupon, then add tax to see your final sale price.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/percentage-calc/", "/sales-tax-vat-calculator/", "/tip-bill-split-calculator/" ], "answer": "Calculate stacked percent-off discounts, apply a coupon, then add tax to see your final sale price.", "formula": "Applies discounts sequentially: price × (1 − d1) × (1 − d2), subtracts a coupon, then adds tax: final = (discounted − coupon) × (1 + tax%). The tool also shows the total savings.", "example": "$100 item, 20% off, a $10 coupon, and 8% tax: (80 − 10) × 1.08 = $75.60.", "assumptions": [ "Percent discounts apply before the coupon.", "Tax applies to the discounted total.", "Discounts are multiplicative, not additive." ], "sources": [ { "organization": "Wikipedia", "title": "Discounts and allowances", "url": "https://en.wikipedia.org/wiki/Discounts_and_allowances" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate a discount?", "Subtract the percent: $100 × (1 − 0.20) = $80. Stacked discounts multiply sequentially." ], [ "Do two 10% discounts equal 20% off?", "No — 0.9 × 0.9 = 0.81, which is 19% off, not 20%." ], [ "When is tax applied?", "The tool applies tax after discounts and coupons — the standard in most US states." ], [ "Should I use the coupon before or after the discount?", "Most stores apply percent discounts first, then coupons — the tool follows that order." ], [ "How do I calculate savings?", "Original price − final price. The tool shows this directly." ], [ "Why is my receipt different?", "Store-specific order of operations (coupon before discount, tax on original) changes the math." ], [ "Is a coupon ever better than a discount?", "Sometimes — a fixed coupon can beat a percent discount on small purchases. Run both through the calculator." ], [ "How do I stack percentage discounts?", "Apply them one at a time: 20% off then 10% off leaves 72% of the original, not 70%." ], [ "Does the coupon apply before or after the percent?", "Retail order is percent first, coupon second, then tax — the calculator follows that order." ], [ "Is tax calculated on the discounted price?", "Yes — tax applies to the final discounted amount, not the original price." ], [ "How do I compare a percent off and a dollar off?", "Convert both to dollars saved at your actual price; the bigger saving wins." ] ] }, { "slug": "distance-between-coordinates-calculator", "name": "Distance Between Coordinates Calculator", "canonical_url": "https://boringtoolskit.com/distance-between-coordinates-calculator/", "category": "Geography", "description": "Distance between coordinates calculator: great-circle distance (haversine) between two latitude/longitude points.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "distance-between-zips-calculator", "name": "Distance Between ZIP Codes Calculator", "canonical_url": "https://boringtoolskit.com/distance-between-zips-calculator/", "category": "Converters", "description": "Distance between ZIP codes calculator: straight-line miles.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "distance-modulus-calculator", "name": "Distance Modulus Calculator", "canonical_url": "https://boringtoolskit.com/distance-modulus-calculator/", "category": "Astronomy", "description": "Distance modulus calculator: distance from apparent and absolute magnitude.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "dividend-reinvestment-calculator", "name": "Dividend Reinvestment Calculator", "canonical_url": "https://boringtoolskit.com/dividend-reinvestment-calculator/", "category": "Finance & Investing", "description": "Estimate portfolio growth when dividends are reinvested with editable yield and price growth.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/dca-investment-calculator/", "/compound-interest/", "/cagr-calculator/" ], "answer": "Estimate portfolio growth when dividends are reinvested with editable yield and price growth.", "formula": "Simulates monthly: dividend = current value × yield ÷ 12, reinvested into more shares, while the share price grows at the growth rate. Final value = accumulated shares × price; total dividends = sum of payments.", "example": "$10,000 at a 3% yield and 2% growth over 10 years: value grows to roughly $16,500 with ~$3,900 in cumulative dividends reinvested.", "assumptions": [ "Dividends are reinvested monthly at the stated yield.", "Growth is constant and compounded.", "Taxes on dividends are not modeled." ], "sources": [ { "organization": "Wikipedia", "title": "Dividend reinvestment plan", "url": "https://en.wikipedia.org/wiki/Dividend_reinvestment_plan" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How does dividend reinvestment work?", "Dividends buy more shares, which pay more dividends — compounding income. The calculator projects the total effect." ], [ "Why reinvest instead of taking cash?", "Reinvested dividends compound: $10,000 at 3% yield with 2% growth becomes ~$16,500 in 10 years — more than price growth alone." ], [ "What is yield?", "Annual dividends per share ÷ share price. A 3% yield on $10,000 pays $300/year." ], [ "Are dividends taxed?", "Yes — qualified dividends are taxed at capital gains rates, ordinary dividends as income. The tool doesn't model taxes." ], [ "Do companies cut dividends?", "Yes — yields change with earnings and payouts. Use conservative assumptions for planning." ], [ "How do I set this up?", "Most brokerages offer automatic dividend reinvestment (DRIP) — enable it on the account." ], [ "Is this the same as a DRIP?", "A DRIP is the formal reinvestment plan; the calculator models the same compounding effect." ], [ "What is dividend reinvestment?", "Using dividend payments to buy more shares — compounding the yield over time." ], [ "Does reinvesting really matter?", "Yes — over a decade, reinvested dividends can add thousands beyond price growth." ], [ "Should I reinvest or take cash?", "Reinvest in accumulation; take cash when you need the income." ], [ "Are reinvested dividends taxed?", "Yes — taxable in the year received, even though no cash reaches you." ] ] }, { "slug": "dividend-yield-calculator", "name": "Dividend Yield Calculator", "canonical_url": "https://boringtoolskit.com/dividend-yield-calculator/", "category": "Finance & Investing", "description": "Dividend yield calculator: yield from annual dividends per share and price, plus income for your shares.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "dna-gc-content-calculator", "name": "DNA GC Content Calculator", "canonical_url": "https://boringtoolskit.com/dna-gc-content-calculator/", "category": "Biology", "description": "DNA GC content calculator: GC and AT percentage from nucleotide counts.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "dog-food-calculator", "name": "Dog Food Calculator", "canonical_url": "https://boringtoolskit.com/dog-food-calculator/", "category": "Pets", "description": "Dog food calculator: daily calories and cups from dog weight.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "dot-product-calculator", "name": "Dot Product Calculator", "canonical_url": "https://boringtoolskit.com/dot-product-calculator/", "category": "Everyday Calculators", "description": "Dot product calculator: scalar product of two 3D vectors.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "doubling-time-calculator", "name": "Doubling Time Calculator", "canonical_url": "https://boringtoolskit.com/doubling-time-calculator/", "category": "Biology", "description": "Doubling time calculator: population or cell culture generation time from start and end counts.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "down-payment-calculator", "name": "Down Payment Calculator", "canonical_url": "https://boringtoolskit.com/down-payment-calculator/", "category": "Finance & Investing", "description": "Calculate your down payment, loan amount, closing costs, and cash needed to close in percent or dollar-amount mode.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/mortgage-payment-calculator/", "/rent-vs-buy-calculator/", "/closing-cost-calculator/" ], "answer": "Calculate your down payment, loan amount, closing costs, and cash needed to close in percent or dollar-amount mode.", "formula": "Down payment = home price × down payment % (or the entered amount). Cash needed = down payment + closing costs (closing % × price), compared against available cash.", "example": "A $300,000 home with 20% down: $60,000 down payment; with 3% closing costs ($9,000), total cash needed is $69,000.", "assumptions": [ "Closing costs are a flat percent of the price.", "The buyer pays down payment plus closing costs from cash.", "PMI and escrow are evaluated separately." ], "sources": [ { "organization": "Wikipedia", "title": "Down payment", "url": "https://en.wikipedia.org/wiki/Down_payment" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a down payment?", "The upfront cash you pay toward a home's purchase price; the mortgage covers the rest." ], [ "How much should I put down?", "20% avoids PMI and lowers payments on conventional loans; 3–10% works with FHA and other programs but adds costs." ], [ "What are closing costs?", "Fees for the loan, title, appraisal, and recording — typically 2–5% of the price, on top of the down payment." ], [ "What is PMI?", "Private mortgage insurance required when your down payment is under 20% — it adds to the monthly payment until you build 20% equity." ], [ "How is cash needed calculated?", "Down payment plus closing costs. On a $300,000 home at 20% down and 3% closing: $60,000 + $9,000 = $69,000." ], [ "Can I buy with 5% down?", "Yes — FHA loans allow 3.5%, and some conventional programs allow 3–5%, but you'll pay PMI and possibly a higher rate." ], [ "What else should my cash cover?", "Inspection fees, moving costs, immediate repairs, and an emergency fund — don't drain everything into the purchase." ], [ "How much down payment do I need?", "20% avoids PMI; programs allow 3–10% with different costs." ], [ "What does 20% down save?", "No PMI and a lower loan amount — often hundreds monthly." ], [ "Can I buy with 3% down?", "Yes — conventional and FHA programs allow it, with PMI and higher payments." ], [ "Is the down payment the full cash needed?", "No — add closing costs and prepaids for total cash to close." ] ] }, { "slug": "dpi-calculator", "name": "DPI Calculator", "canonical_url": "https://boringtoolskit.com/dpi-calculator/", "category": "Converters", "description": "DPI calculator: pixels per inch from pixel dimensions and print size.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "dps-calculator", "name": "DPS Calculator", "canonical_url": "https://boringtoolskit.com/dps-calculator/", "category": "Gaming", "description": "DPS calculator: damage per second from average hit damage and attack rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "dress-size-converter", "name": "Dress Size Converter", "canonical_url": "https://boringtoolskit.com/dress-size-converter/", "category": "Converters", "description": "Dress size converter: US to EU and UK dress sizes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "drywall-calculator", "name": "Drywall Calculator", "canonical_url": "https://boringtoolskit.com/drywall-calculator/", "category": "Construction & Measurement", "description": "Estimate drywall sheets, joint compound, screws, waste, and optional sheet cost for a room.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/paint-coverage-calculator/", "/flooring-calculator/", "/board-foot-calculator/" ], "answer": "Estimate drywall sheets, joint compound, screws, waste, and optional sheet cost for a room.", "formula": "Net area = wall perimeter × height + optional ceiling − openings; sheets = ceiling(net area × (1 + waste) ÷ sheet area).", "example": "", "assumptions": [ "Room is rectangular and uses one drywall layer.", "Opening deductions and waste are entered by the user.", "Fasteners and joint compound are rough planning estimates; manufacturer instructions control." ], "sources": [ { "organization": "USG", "title": "Drywall installation resources", "url": "https://www.usg.com/content/usgcom/en/resource-center.html" }, { "organization": "OSHA", "title": "Drywall and construction safety resources", "url": "https://www.osha.gov/construction" } ], "faqs": [ [ "What is a drywall calculator?", "A drywall calculator is a free, browser-based tool that estimates the number of drywall sheets and joint compound needed for your project without requiring any personal information or signup." ], [ "Do I need to create an account to use this drywall calculator?", "No, this drywall calculator is completely no-signup and runs entirely in your browser, so your measurements and data are never stored or sent to a server." ], [ "How accurate are the estimates from this drywall calculator?", "The drywall calculator provides highly accurate estimates based on your room dimensions, but it is honest to note that you should add a 10-15% waste factor for cuts and irregular shapes." ] ] }, { "slug": "dscr-calculator", "name": "DSCR Calculator", "canonical_url": "https://boringtoolskit.com/dscr-calculator/", "category": "Real Estate", "description": "Debt service coverage ratio calculator: net operating income against annual debt payments for rental properties.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "due-date-calculator", "name": "Due Date Calculator", "canonical_url": "https://boringtoolskit.com/due-date-calculator/", "category": "Everyday Calculators", "description": "Estimate your pregnancy due date from your last period or conception date.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/pregnancy-calculator/", "/ovulation-calculator/", "/ideal-weight-calculator/" ], "answer": "Estimate your pregnancy due date from your last period or conception date.", "formula": "Due date = last menstrual period (LMP) + 280 days (40 weeks). Conception date ≈ due date − 266 days. From conception date mode: due date = conception + 266 days.", "example": "With LMP of January 1: due date = January 1 + 280 days = October 8. Conception ≈ January 16.", "assumptions": [ "A regular 28-day cycle with ovulation at day 14.", "The pregnancy is a single baby (multiples often deliver earlier).", "The entered LMP or conception date is accurate." ], "sources": [ { "organization": "ACOG", "title": "Methods for Estimating the Due Date", "url": "https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2017/05/methods-for-estimating-the-due-date" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How is my due date calculated?", "From your last menstrual period: add 280 days (40 weeks). From conception: add 266 days. The tool supports both." ], [ "Why 280 days?", "A typical pregnancy is about 40 weeks from the first day of the last period — 280 days. That assumes ovulation at day 14 of a 28-day cycle." ], [ "How accurate is the due date?", "Only about 5% of babies arrive on the exact date. A due date is an estimate; full-term labor ranges from about 37 to 42 weeks." ], [ "What if my cycle is irregular?", "The LMP method assumes a regular 28-day cycle. Your provider may adjust the date using an early ultrasound, which is more accurate." ], [ "What is the conception date?", "The estimated day of fertilization — about 14 days after the LMP, or 266 days before the due date." ], [ "When does the third trimester start?", "Around 28 weeks. The tool shows the estimated trimester at the end of the calculation." ], [ "Do twins have a different due date?", "The estimated due date is the same, but multiples often deliver earlier — typically planned around 37–38 weeks." ] ] }, { "slug": "ebay-fee-calculator", "name": "eBay Fee Calculator", "canonical_url": "https://boringtoolskit.com/ebay-fee-calculator/", "category": "Seller & Business", "description": "eBay fee calculator: final value fees and net proceeds for a sale including shipping.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "ebay-fee-profit-calculator", "name": "eBay Fee and Profit Calculator", "canonical_url": "https://boringtoolskit.com/ebay-fee-profit-calculator/", "category": "Seller & Business", "description": "Free eBay fee calculator: estimate final value, per-order, and promoted-listing fees plus net profit and margin , with editable 2026 fee rates.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/amazon-seller-fee-calculator/", "/etsy-fee-profit/", "/commission-calculator/" ], "answer": "Free eBay fee calculator: estimate final value, per-order, and promoted-listing fees plus net profit and margin , with editable 2026 fee rates.", "formula": "Revenue = sale price + shipping charged. Fees = revenue × (final value fee % + promoted rate %) + fixed fee. Net = revenue − fees − item cost − shipping cost.", "example": "A $40 item with $5 shipping at 13.25% final value fee + $0.30: fees ≈ $6.26 on $45 revenue.", "assumptions": [ "The final value fee applies to item + shipping.", "Promoted rate applies when the seller opts in.", "Insertion-fee allowances and subscriptions are separate." ], "sources": [ { "organization": "Wikipedia", "title": "eBay", "url": "https://en.wikipedia.org/wiki/Ebay" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How much does eBay charge?", "A final value fee on the total (item + shipping) — typically 13.25% plus $0.30 for most categories, plus promoted-listing fees if you use ads." ], [ "How do I calculate eBay profit?", "Revenue minus fees minus costs. A $40 + $5 shipping item at 13.25% + $0.30 costs about $6.26 in fees." ], [ "Does the fee include shipping?", "Yes — eBay charges the final value fee on the full payment, shipping included." ], [ "What is the promoted rate?", "The ad fee (2–15%+) you pay only when a buyer reaches your listing through promoted placement." ], [ "How do fees compare to Etsy or Amazon?", "eBay ~13.25% + $0.30 is mid-range; Amazon referral is ~15%, Etsy ~6.5% + payment fees. Use each site's calculator for your category." ], [ "What about insertion fees?", "Basic sellers get free listings each month; beyond that, insertion fees apply per listing." ], [ "When do fees change?", "eBay adjusts rates periodically — re-run the calculator after announcements." ], [ "What is the eBay final value fee?", "A percentage of the total sale including shipping — commonly 13.25% for most categories." ], [ "Does the fee apply to shipping?", "Yes — the final value fee is on the total the buyer pays, including shipping." ], [ "What are promoted listing fees?", "A percentage of the sale (2–15%) charged only when the promotion leads to a sale." ] ] }, { "slug": "ebitda-calculator", "name": "EBITDA Calculator", "canonical_url": "https://boringtoolskit.com/ebitda-calculator/", "category": "Finance & Investing", "description": "EBITDA calculator: earnings before interest, taxes, depreciation, amortization.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "effective-field-goal-percentage-calculator", "name": "Effective Field Goal Percentage Calculator", "canonical_url": "https://boringtoolskit.com/effective-field-goal-percentage-calculator/", "category": "Sports", "description": "Effective field goal percentage calculator: eFG% that counts threes as 1.5 makes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "egg-boil-time-calculator", "name": "Egg Boil Time Calculator", "canonical_url": "https://boringtoolskit.com/egg-boil-time-calculator/", "category": "Food & Cooking", "description": "Egg boil time calculator: doneness from boiling minutes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "electric-bill-estimator", "name": "Electric Bill Estimator", "canonical_url": "https://boringtoolskit.com/electric-bill-estimator/", "category": "Energy & Electrical", "description": "Electric bill estimator: monthly bill from kWh usage, rate, and fixed fees.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "electricity-cost-calculator", "name": "Electricity Cost Calculator", "canonical_url": "https://boringtoolskit.com/electricity-cost-calculator/", "category": "Energy & Electrical", "description": "Estimate appliance energy use and daily, monthly, and annual electricity cost.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/energy-cost-tools/", "/research/appliance-electricity-cost-scenarios/", "/led-savings-calculator/", "/ev-charging-cost-calculator/", "/watts-to-amps-calculator/" ], "answer": "Appliance electricity cost: estimate and compare daily, monthly, and annual electricity use from watts, runtime, active days, and your entered rate.", "formula": "For each appliance: monthly kWh = watts ÷ 1,000 × hours per active day × active days per month; annual kWh = monthly kWh × 12; cost = kWh × electricity rate. Comparison mode subtracts Appliance B from Appliance A and simple payback = additional purchase cost ÷ annual savings when annual savings are positive.", "example": "A 1,500-watt appliance used 4 hours per day for 30 active days at $0.20 per kWh uses 180 kWh and costs $36 for that month; annualizing the same entered schedule gives $432.", "assumptions": [ "Power draw, active hours, and active days are treated as constant user assumptions.", "Annual use follows the entered monthly schedule by multiplying monthly kWh by 12.", "Taxes, demand charges, time-of-use rates, standby power, maintenance, rebates, and lifespan are excluded unless you account for them separately.", "Worked example: A 1,500-watt appliance used 4 hours per day for 30 active days at $0.20 per kWh uses 180 kWh and costs $36 for that month; annualizing the same schedule gives $432.", "Nameplate watts may differ from average draw as appliances cycle, enter standby, or change load." ], "sources": [ { "organization": "U.S. Energy Information Administration", "title": "Electricity use in homes", "url": "https://www.eia.gov/energyexplained/use-of-energy/electricity-use-in-homes.php" }, { "organization": "U.S. Energy Information Administration", "title": "Average retail price of electricity", "url": "https://www.eia.gov/electricity/data/browser/" } ], "faqs": [] }, { "slug": "electron-configuration-calculator", "name": "Electron Configuration Calculator", "canonical_url": "https://boringtoolskit.com/electron-configuration-calculator/", "category": "Chemistry", "description": "Find the electron configuration for any element by atomic number.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/molar-mass-calculator/", "/average-atomic-mass-calculator/", "/empirical-formula-calculator/" ], "answer": "Find the electron configuration for any element by atomic number.", "formula": "Fills electrons into orbitals following the Aufbau order (1s, 2s, 2p, 3s, 3p, 4s, 3d, ...) for the given atomic number (1–118).", "example": "Atomic number 8 (oxygen): 1s² 2s² 2p⁴. Atomic number 26 (iron): [Ar] 3d⁶ 4s².", "assumptions": [ "The atomic number must be between 1 and 118.", "The configuration follows the standard Aufbau sequence (with common exceptions for some transition metals not modeled).", "The result is the ground-state electron configuration." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "ellipse-calculator", "name": "Ellipse Calculator", "canonical_url": "https://boringtoolskit.com/ellipse-calculator/", "category": "Everyday Calculators", "description": "Ellipse calculator: area and approximate circumference.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "email-preview-tester", "name": "Email Preview Tester", "canonical_url": "https://boringtoolskit.com/email-preview-tester/", "category": "Text & Developer Tools", "description": "Preview sender, subject line, and preheader truncation across representative inbox layouts. Runs privately in your browser.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/markdown-table-generator/", "/text-case/", "/word-counter/" ], "answer": "Preview sender, subject line, and preheader truncation across representative inbox layouts. Runs privately in your browser.", "formula": "Checks subject lines and sender names against client display budgets (Gmail, Apple Mail, Outlook, Yahoo) in compact, wide, and desktop layouts, flagging likely truncation.", "example": "A 60-character subject line truncates in Gmail's compact view (34–46 char budget) but may fit on desktop.", "assumptions": [ "Client display budgets reflect current layouts.", "Character counts are approximate.", "The subject is the first line of the email." ], "sources": [ { "organization": "Wikipedia", "title": "Email", "url": "https://en.wikipedia.org/wiki/Email" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I test an email subject line?", "Enter it in the tester — the tool simulates each client's display budget and flags truncation." ], [ "What is the ideal subject length?", "Under ~40 characters for safety on mobile compact views; longer works on desktop." ], [ "Why does my subject truncate in Gmail?", "Gmail's compact view budgets roughly 34–46 characters for the subject — anything longer gets cut." ], [ "Does the sender name count?", "Yes — it shares the same display line and eats into the subject's space." ], [ "Do emoji affect length?", "Yes — they render wider than one character and consume more display space." ], [ "What's the difference between layouts?", "Compact (mobile), wide (tablet), and desktop clients each allocate different character budgets." ], [ "Is this a deliverability test?", "No — it's a display test. Deliverability (spam placement) is a separate concern." ], [ "What is preview text?", "The snippet shown after the subject in most email clients — the second line of your pitch." ], [ "How long should a subject be?", "30–40 characters for mobile safety; the tester shows each client's truncation." ], [ "Does preview text truncate?", "Yes — mobile shows fewer characters than desktop; the tester simulates both." ], [ "Is this a deliverability tester?", "No — it tests the visible inbox presentation; deliverability needs full-send testing." ] ] }, { "slug": "emergency-fund-calculator", "name": "Emergency Fund Calculator", "canonical_url": "https://boringtoolskit.com/emergency-fund-calculator/", "category": "Finance & Investing", "description": "Estimate an emergency-fund target, current gap, and time needed to reach it.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/savings-goal-calculator/", "/savings-calc/", "/credit-card-payoff-calculator/" ], "answer": "Estimate an emergency-fund target, current gap, and time needed to reach it.", "formula": "Target = monthly expenses × months of coverage. Gap = target − current savings. Time to reach = gap ÷ monthly contribution.", "example": "$4,000 monthly expenses × 6 months = a $24,000 emergency fund target.", "assumptions": [ "Expenses are essential, recurring costs.", "The fund is held separately and untouched.", "The monthly contribution is sustained." ], "sources": [ { "organization": "Wikipedia", "title": "Emergency fund", "url": "https://en.wikipedia.org/wiki/Emergency_fund" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How much should my emergency fund be?", "3–6 months of essential expenses is the standard guide — more if your income is variable. $4,000/mo × 6 = $24,000." ], [ "What counts as essential expenses?", "Housing, utilities, food, transportation, insurance, and debt minimums — the costs you can't cut quickly." ], [ "Where should I keep it?", "In a separate high-yield savings account — accessible without penalties, but not attached to your daily card." ], [ "How long will it take to build?", "The calculator divides the gap by your monthly savings: a $12,000 gap at $500/mo takes 24 months." ], [ "Is 1 month enough to start?", "Yes — start with one month, then grow toward 3–6. Any buffer beats none." ], [ "When can I invest it instead?", "Once it's at 6 months, extra savings can go to investments — the fund itself stays liquid." ], [ "Should I use it for repairs?", "That's exactly what it's for — genuine emergencies. Rebuild it afterward." ], [ "How fast should I build it?", "As fast as possible without sacrificing high-interest debt payoff — the calculator shows the monthly amount for any timeline." ] ] }, { "slug": "emi-calculator", "name": "EMI Calculator", "canonical_url": "https://boringtoolskit.com/emi-calculator/", "category": "Everyday Calculators", "description": "Calculate the equated monthly installment (EMI) for a fixed-rate loan, plus total interest and an amortization schedule.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/amortization-calculator/", "/loan-comparison-calculator/", "/auto-loan-calculator/" ], "answer": "Calculate the equated monthly installment (EMI) for a fixed-rate loan, plus total interest and an amortization schedule.", "formula": "EMI = P × r × (1 + r)^n ÷ ((1 + r)^n − 1), where P = principal, r = monthly interest rate (annual ÷ 12), and n = number of monthly payments. Total payment = EMI × n; total interest = total payment − principal.", "example": "A $500,000 loan at 7% for 20 years (240 months): r = 0.07 ÷ 12 ≈ 0.005833, EMI ≈ $3,876/month.", "assumptions": [ "The interest rate is fixed for the full term.", "Payments are made monthly at the end of each period.", "Fees, insurance, and taxes are not included." ], "sources": [ { "organization": "CalculatorSoup", "title": "Loan Calculator", "url": "https://www.calculatorsoup.com/calculators/financial/loan-calculator.php" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is EMI?", "Equated monthly installment — the fixed monthly payment that repays a loan (principal plus interest) by the end of its term." ], [ "How is EMI calculated?", "EMI = P × r × (1+r)^n ÷ ((1+r)^n − 1), where r is the monthly rate (annual ÷ 12) and n the number of months." ], [ "What happens if the rate is floating?", "The EMI recalculates when the rate resets — it can rise or fall. This calculator assumes a fixed rate for the entered term." ], [ "How can I lower my EMI?", "Extend the term (lowers the payment but raises total interest), negotiate a lower rate, or increase the down payment to reduce the principal." ], [ "Why is most of my early payment interest?", "Interest is charged on the outstanding balance, which is largest at the start. As principal falls, the interest share shrinks — that's how amortization works." ], [ "Does this include processing fees?", "No. Fees, insurance, and other charges are added by the lender on top of the EMI math." ], [ "Which is better: shorter or longer term?", "A shorter term costs more per month but far less in total interest. Choose based on your cash flow and total cost goals." ] ] }, { "slug": "empirical-formula-calculator", "name": "Empirical Formula Calculator", "canonical_url": "https://boringtoolskit.com/empirical-formula-calculator/", "category": "Chemistry", "description": "Find the empirical formula from percent composition or mass data.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/molar-mass-calculator/", "/average-atomic-mass-calculator/", "/percent-yield-calculator/" ], "answer": "Find the empirical formula from percent composition or mass data.", "formula": "Convert each element's mass or percent to moles (mass ÷ atomic mass), divide by the smallest value, and round to the nearest whole-number ratio to get the empirical formula.", "example": "For a compound that is 40% C, 6.7% H, 53.3% O: moles ≈ 3.33 C, 6.65 H, 3.33 O → ratio 1:2:1 → CH₂O.", "assumptions": [ "Each element's mass or percent is entered as element:value or element,value.", "Atomic masses use the standard values embedded in the tool.", "The result is the simplest whole-number ratio, not necessarily the molecular formula." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "employee-turnover-calculator", "name": "Employee Turnover Calculator", "canonical_url": "https://boringtoolskit.com/employee-turnover-calculator/", "category": "Time & Work", "description": "Employee turnover rate calculator.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "endpoint-calculator", "name": "Endpoint Calculator", "canonical_url": "https://boringtoolskit.com/endpoint-calculator/", "category": "Everyday Calculators", "description": "Endpoint calculator: missing endpoint from midpoint and one endpoint.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "energy-converter", "name": "Energy Converter", "canonical_url": "https://boringtoolskit.com/energy-converter/", "category": "Converters", "description": "Energy converter: joules, kilowatt-hours, calories, BTUs.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "engagement-rate-calculator", "name": "Engagement Rate Calculator", "canonical_url": "https://boringtoolskit.com/engagement-rate-calculator/", "category": "Social Media", "description": "Calculate social media engagement rate from followers, likes, comments, and shares.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/instagram-influencer-pricing-calculator/", "/hashtag-performance-calculator/", "/follower-growth-calculator/" ], "answer": "Calculate social media engagement rate from followers, likes, comments, and shares.", "formula": "Engagement rate = (likes + comments + shares) ÷ followers × 100. Interactions = likes + comments + shares.", "example": "A post with 120 likes, 12 comments, and 8 shares on 5,000 followers: interactions = 140, rate = 140 ÷ 5,000 × 100 = 2.80%.", "assumptions": [ "Engagement is limited to likes, comments, and shares entered.", "The follower count is the audience at the time of the post.", "Rates are a planning metric; platform algorithms and reach are not modeled." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "engine-horsepower-calculator", "name": "Engine Horsepower Calculator", "canonical_url": "https://boringtoolskit.com/engine-horsepower-calculator/", "category": "Vehicles", "description": "Engine horsepower calculator: estimate HP from weight and quarter-mile ET (trap method).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "eoq-calculator", "name": "EOQ Calculator", "canonical_url": "https://boringtoolskit.com/eoq-calculator/", "category": "Finance & Investing", "description": "EOQ calculator: economic order quantity for inventory.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "equalizer-q-calculator", "name": "Equalizer Q Calculator", "canonical_url": "https://boringtoolskit.com/equalizer-q-calculator/", "category": "Music & Audio", "description": "Equalizer Q calculator: filter Q from center frequency and bandwidth, in Hz or octaves.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "equilibrium-constants-calculator", "name": "Equilibrium Constant Calculator", "canonical_url": "https://boringtoolskit.com/equilibrium-constants-calculator/", "category": "Chemistry", "description": "Calculate the equilibrium constant K from reactant and product concentrations.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/buffer-solution-calculator/", "/reaction-rate-calculator/", "/gas-laws-calculator/" ], "answer": "Calculate the equilibrium constant K from reactant and product concentrations.", "formula": "For aA + bB ⇌ cC + dD, K = [C]^c × [D]^d ÷ [A]^a × [B]^b.", "example": "For 2A ⇌ C (a = 2, c = 1), with [A] = 0.5 M and [C] = 0.2 M: K = 0.2 ÷ (0.5)² = 0.8.", "assumptions": [ "Coefficients and concentrations for the products and at least one reactant are required.", "Concentrations use the entered values; the tool does not solve for equilibrium positions.", "Solids and pure liquids are not entered in the concentration terms." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "estate-tax-calculator", "name": "Estate Tax Calculator", "canonical_url": "https://boringtoolskit.com/estate-tax-calculator/", "category": "Finance & Investing", "description": "Estate tax calculator: federal estate tax above the lifetime exemption.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "etsy-fee-profit", "name": "Etsy Fee & Profit Calculator", "canonical_url": "https://boringtoolskit.com/etsy-fee-profit/", "category": "Seller & Business", "description": "Free Etsy fee calculator: estimate listing, transaction, and payment processing fees plus profit. Enter price and costs, see net earnings and margins. Privat.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/amazon-seller-fee-calculator/", "/break-even-units-calculator/", "/commission-calculator/" ], "answer": "Free Etsy fee calculator: estimate listing, transaction, and payment processing fees plus profit. Enter price and costs, see net earnings and margins. Privat.", "formula": "Gross = sale price × quantity + shipping charged. Fees = listing fee ($0.20/item) + transaction fee (6.5% of gross) + payment processing (3% + $0.25) + offsite ads % + other. Net = gross − fees − costs.", "example": "A $30 item: transaction fee $1.95, payment processing ~$1.15, listing $0.20 — about $3.30 in fees before shipping and costs.", "assumptions": [ "Current Etsy fee rates apply (listing $0.20, transaction 6.5%).", "Payment processing is 3% + $0.25 per transaction.", "The offsite ads rate reflects the seller's tier." ], "sources": [ { "organization": "Wikipedia", "title": "Etsy", "url": "https://en.wikipedia.org/wiki/Etsy" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How much does Etsy charge?", "A $0.20 listing fee per item, 6.5% transaction fee on the sale total, and payment processing (~3% + $0.25) — plus offsite ads on qualifying sales." ], [ "How do I calculate Etsy profit?", "Gross (sale + shipping) minus all fees minus item cost = net. A $30 item nets about $26 after core fees." ], [ "What is the offsite ads fee?", "Etsy advertises your items; on sales from that traffic it takes 12–15% — depending on your annual sales volume." ], [ "Is the listing fee per item or per sale?", "Per item listed — $0.20 each, renewed every 4 months." ], [ "Why is my net lower than expected?", "Fees stack: transaction (6.5%), payment (~3%+$0.25), listing, offsite ads, plus shipping and materials." ], [ "How do I improve margins?", "Raise prices to absorb fees, bundle shipping, reduce material cost, or move high-fee items to your own site." ], [ "Do fees change?", "Yes — Etsy adjusts rates periodically. Re-run the calculator after announcements." ], [ "What are Etsy's fees?", "$0.20 listing, 6.5% transaction, ~3% + $0.25 processing, and 12–15% for offsite-ads orders." ], [ "How do I price for a target profit?", "Work backward through the fee stack — the calculator's reverse view does it." ] ] }, { "slug": "ev-charge-time-calculator", "name": "EV Charge Time Calculator", "canonical_url": "https://boringtoolskit.com/ev-charge-time-calculator/", "category": "Vehicles", "description": "EV charge time calculator: hours to charge an EV battery.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "ev-charging-cost-calculator", "name": "EV Charging Cost Calculator", "canonical_url": "https://boringtoolskit.com/ev-charging-cost-calculator/", "category": "Energy & Electrical", "description": "Estimate energy drawn, per-charge cost, monthly charging cost, and cost per mile for an EV.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/electricity-cost-calculator/", "/battery-runtime-calculator/", "/watts-to-amps-calculator/" ], "answer": "Estimate energy drawn, per-charge cost, monthly charging cost, and cost per mile for an EV.", "formula": "Battery energy added = capacity × charge-window percentage; grid energy = battery energy ÷ (1 − loss); cost = grid energy × rate.", "example": "", "assumptions": [ "Usable battery capacity equals the entered capacity.", "Charging loss and electricity rate remain constant.", "Taxes, demand charges, time-of-use pricing, idle fees, and public-network fees are excluded." ], "sources": [ { "organization": "U.S. Department of Energy", "title": "Electric vehicle charging at home", "url": "https://afdc.energy.gov/fuels/electricity_charging_home.html" }, { "organization": "EPA", "title": "FuelEconomy.gov electric vehicles", "url": "https://www.fueleconomy.gov/feg/evtech.shtml" } ], "faqs": [ [ "How much does it cost to charge an EV at home?", "Multiply the grid energy (battery kWh ÷ (1 − charging loss)) by your electricity rate. At $0.17/kWh with 90% efficiency, a 40 kWh charge costs about $7.56." ], [ "Why is more energy drawn from the wall than the battery holds?", "Charging is not 100% efficient; some energy is lost to heat and the charging electronics. Dividing by (1 − loss) accounts for that loss." ], [ "Does this include public charging stations?", "No — it models home charging. Public stations add their own network fees and per-minute or idle fees." ], [ "What electricity rate should I use?", "Use your own home rate in $/kWh, including any time-of-use variation if you charge when rates are lower." ] ] }, { "slug": "ev-range-calculator", "name": "EV Range Calculator", "canonical_url": "https://boringtoolskit.com/ev-range-calculator/", "category": "Vehicles", "description": "EV range calculator: electric car range from battery and consumption.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "ev-vs-gas-savings-calculator", "name": "EV vs Gas Savings Calculator", "canonical_url": "https://boringtoolskit.com/ev-vs-gas-savings-calculator/", "category": "Vehicles", "description": "EV vs gas savings calculator: annual fuel cost of an electric car versus a gas car.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "expected-value-calculator", "name": "Expected Value Calculator", "canonical_url": "https://boringtoolskit.com/expected-value-calculator/", "category": "Statistics", "description": "Expected value calculator: EV from two outcomes with probabilities and values.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "expense-split-calculator", "name": "Expense Split Calculator", "canonical_url": "https://boringtoolskit.com/expense-split-calculator/", "category": "Time & Work", "description": "Expense split calculator: split a bill evenly.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "exponent-calculator", "name": "Exponent Calculator", "canonical_url": "https://boringtoolskit.com/exponent-calculator/", "category": "Everyday Calculators", "description": "Calculate a base raised to an exponent, including negative and fractional exponents.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/log-calculator/", "/fractions-calculator/", "/quadratic-formula-calculator/" ], "answer": "Calculate a base raised to an exponent, including negative and fractional exponents.", "formula": "Result = base^exponent (Math.pow(base, exponent)). Negative exponents give the reciprocal: 2⁻² = 1 ÷ 2² = 0.25. Fractional exponents give roots: 8^(1/3) = 2.", "example": "2^10 = 1024. 2⁻² = 1 ÷ 4 = 0.25 (reciprocal). 8^(1/3) = 2 (cube root). Any non-zero base to the 0th power equals 1.", "assumptions": [ "Standard real-number exponentiation applies.", "Results are finite and real (complex results are flagged invalid).", "Zero to a negative exponent is undefined." ], "sources": [ { "organization": "Math Is Fun", "title": "Exponents", "url": "https://www.mathsisfun.com/exponent.html" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is an exponent?", "The number of times a base is multiplied by itself: 2^5 means 2×2×2×2×2. It's shorthand for repeated multiplication." ], [ "What does a negative exponent mean?", "The reciprocal: 2⁻² = 1 ÷ 2² = 0.25. Negative exponents don't make the result negative." ], [ "What is 2^0?", "Any non-zero base to the power of 0 equals 1." ], [ "What is a fractional exponent?", "A root: 8^(1/3) = 2 (cube root), 16^(1/2) = 4 (square root). The denominator of the fraction is the root." ], [ "What is scientific notation?", "A compact way to write very large or small numbers using powers of 10, e.g., 6.02 × 10²³. Exponents move the decimal point." ], [ "Why does the tool say invalid?", "The result is either infinite (overflow), or the operation isn't real (like a fractional power of a negative base). Check the base/exponent combination." ], [ "Where is exponentiation used in real life?", "Compound interest, population growth, doubling times, computer memory (2^10 = 1024 bytes = 1 KB), and physics scaling." ] ] }, { "slug": "exponential-growth-calculator", "name": "Exponential Growth Calculator", "canonical_url": "https://boringtoolskit.com/exponential-growth-calculator/", "category": "Everyday Calculators", "description": "Exponential growth calculator: value after continuous growth.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "exposure-value-calculator", "name": "Exposure Value Calculator", "canonical_url": "https://boringtoolskit.com/exposure-value-calculator/", "category": "Photo & Video", "description": "Exposure value calculator: EV from aperture, shutter speed, and ISO.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "fabric-yardage-calculator", "name": "Fabric Yardage Calculator", "canonical_url": "https://boringtoolskit.com/fabric-yardage-calculator/", "category": "Construction & Measurement", "description": "Fabric yardage calculator: yards of fabric for a project.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "facebook-ads-cost-calculator", "name": "Facebook Ads Cost Calculator", "canonical_url": "https://boringtoolskit.com/facebook-ads-cost-calculator/", "category": "Social Media", "description": "Calculate Facebook ads CPM, CPC, CTR, and ROAS from campaign data.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/instagram-influencer-pricing-calculator/", "/engagement-rate-calculator/", "/social-media-earnings-calculator/" ], "answer": "Calculate Facebook ads CPM, CPC, CTR, and ROAS from campaign data.", "formula": "Estimated spend = impressions × (CTR ÷ 100) × CPC. Clicks = impressions × (CTR ÷ 100).", "example": "100,000 impressions at a 1.5% CTR and $0.80 CPC: clicks = 1,500, spend = 1,500 × 0.80 = $1,200.", "assumptions": [ "CTR and CPC are the user's estimates from prior campaigns or benchmarks.", "Impressions, clicks, and cost are not guaranteed to scale linearly with spend.", "Bidding, audience, and creative quality materially change real cost." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "factorial-calculator", "name": "Factorial Calculator", "canonical_url": "https://boringtoolskit.com/factorial-calculator/", "category": "Everyday Calculators", "description": "Factorial calculator: n! for any integer up to 170.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-27", "related_urls": [], "answer": "Factorial calculator: n! for any integer up to 170.", "formula": "n! = n × (n−1) × … × 1, with 0! = 1.", "example": "5! = 5 × 4 × 3 × 2 × 1 = 120.", "assumptions": [ "Standard geometric or arithmetic definitions apply.", "Inputs use the units you choose.", "Results are estimates, not professional advice." ], "sources": [ { "organization": "Standard mathematics definitions", "title": "Arithmetic and geometry formulas", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "fasting-window-calculator", "name": "Fasting Window Calculator", "canonical_url": "https://boringtoolskit.com/fasting-window-calculator/", "category": "Health", "description": "Fasting window calculator: eating window from fast start and length.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "federal-income-tax-calculator", "name": "Federal Income Tax Calculator", "canonical_url": "https://boringtoolskit.com/federal-income-tax-calculator/", "category": "Finance & Investing", "description": "Federal income tax calculator: 2026 federal brackets with standard deduction.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "fence-material-calculator", "name": "Fence Material Calculator", "canonical_url": "https://boringtoolskit.com/fence-material-calculator/", "category": "Construction & Measurement", "description": "Estimate fence sections, posts, rails, and pickets from run length and spacing.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/decking-calculator/", "/square-footage-calculator/", "/property-area-calculator/" ], "answer": "Estimate fence sections, posts, rails, and pickets from run length and spacing.", "formula": "Sections = ceil(fence length ÷ section length). Posts = sections + 1. Rails = sections × rails per section. Pickets = ceil(fence length × 12 ÷ picket width).", "example": "A 120 ft fence with 8 ft sections: 15 sections, 16 posts. With 2 rails per section: 30 rails. With 5.5 in pickets: ceil(120 × 12 ÷ 5.5) = 262 pickets.", "assumptions": [ "A straight fence run with no gates or corners.", "Pickets are installed edge-to-edge at the entered width.", "Posts are placed at each section boundary." ], "sources": [ { "organization": "Wikipedia", "title": "Picket fence", "url": "https://en.wikipedia.org/wiki/Picket_fence" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How many posts do I need for a fence?", "Divide the run by the section length and add one: a 120 ft fence with 8 ft sections needs 15 sections and 16 posts." ], [ "How many pickets do I need?", "Multiply the fence length in inches and divide by the picket width (plus spacing if any). A 120 ft fence with 5.5 in pickets needs about 262." ], [ "How far apart should fence posts be?", "Commonly 6–8 feet apart for wood fences. Longer spans weaken the fence and require beefier rails." ], [ "Do I need corner and gate posts?", "Yes — corners, gates, and ends often need thicker or set-in-concrete posts. The tool counts standard line posts only." ], [ "How many rails per section?", "Typically 2 for a 4 ft fence and 3 for a 6 ft fence. Enter the number your design uses." ], [ "Does this include concrete and hardware?", "No — plan for post concrete, screws/nails, hinges, and latches separately." ], [ "What if my yard isn't straight?", "Break the run into straight segments and calculate each separately, adding corner posts." ] ] }, { "slug": "fence-post-calculator", "name": "Fence Post Calculator", "canonical_url": "https://boringtoolskit.com/fence-post-calculator/", "category": "Construction & Measurement", "description": "Fence post calculator: posts and rails for a fence run.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "fetal-weight-calculator", "name": "Fetal Weight Calculator", "canonical_url": "https://boringtoolskit.com/fetal-weight-calculator/", "category": "Health", "description": "Fetal weight calculator: estimated baby weight from ultrasound (Hadlock).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "fha-loan-calculator", "name": "FHA Loan Calculator", "canonical_url": "https://boringtoolskit.com/fha-loan-calculator/", "category": "Finance & Investing", "description": "FHA loan calculator: payment with mortgage insurance premium (MIP).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "fibonacci-calculator", "name": "Fibonacci Calculator", "canonical_url": "https://boringtoolskit.com/fibonacci-calculator/", "category": "Everyday Calculators", "description": "Fibonacci calculator: nth Fibonacci number.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-27", "related_urls": [], "answer": "Fibonacci calculator: nth Fibonacci number.", "formula": "F(0) = 0, F(1) = 1, and F(n) = F(n−1) + F(n−2) for n ≥ 2.", "example": "The first terms are 0, 1, 1, 2, 3, 5, 8, 13…", "assumptions": [ "Standard geometric or arithmetic definitions apply.", "Inputs use the units you choose.", "Results are estimates, not professional advice." ], "sources": [ { "organization": "Standard mathematics definitions", "title": "Arithmetic and geometry formulas", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "field-goal-probability-calculator", "name": "Field Goal Probability Calculator", "canonical_url": "https://boringtoolskit.com/field-goal-probability-calculator/", "category": "Sports", "description": "Field goal probability calculator: estimated make probability from kick distance.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "final-exam-calculator", "name": "Final Exam Grade Calculator", "canonical_url": "https://boringtoolskit.com/final-exam-calculator/", "category": "School & Education", "description": "See the exact score you need on your final exam to reach your desired course grade.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "August 2026", "related_urls": [ "/grade-calculator/", "/gpa-calculator/", "/school-supply-budget-calculator/" ], "answer": "See the exact score you need on your final exam to reach your desired course grade.", "formula": "Required final score = (desired course grade − current grade × (1 − final weight/100)) ÷ (final weight/100). This is the exact formula the live calculator uses: need = (desired − current×(1−w/100)) ÷ (w/100).", "example": "With a current grade of 84%, a desired course grade of 90%, and a final worth 40%, you need (90 − 84×(1−0.40)) ÷ 0.40 = (90 − 50.4) ÷ 0.40 = 99% on the final. Because the final carries so much weight, a perfect score is required to lift a B− average to an A.", "assumptions": [ "Enter current grade, desired course grade, and final weight as percentages on the same 0–100 scale.", "The final must be the only remaining scored item; if other graded work remains, the true required score differs.", "If the required score is above 100, no realistic final can reach the goal (the calculator reports the resulting course floor)." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculation methodology and verification standard", "url": "/methodology/" }, { "organization": "Wikipedia", "title": "Grading in education", "url": "https://en.wikipedia.org/wiki/Grading_in_education" } ], "faqs": [ [ "What formula does this use?", "Required score = (desired − current × (1 − weight/100)) ÷ (weight/100). The final's weight decides how much leverage the exam has over your course grade." ], [ "What if the required score is over 100?", "The goal is unreachable on the final alone. The calculator still shows the highest course grade a perfect final would yield, so you can see the realistic ceiling." ], [ "What if I can score 0 on the final and still pass?", "That means your current average already exceeds the target even counting a 0 on the final. The calculator reports the course floor so you know the grade is already secured." ], [ "How much are final exams worth?", "A final exam is typically worth 10–30% of a course grade, with 20% a very common default. The exact weight is set by your instructor and usually stated in the syllabus — enter that percentage (e.g. 20) as the final weight to see what score you need. This calculator shows how much leverage a high- or low-weight final has over your course grade." ], [ "How do I calculate my final exam score percentage?", "Your final exam score percentage is simply the percentage of points you earn on the exam: points earned ÷ points possible × 100. If you score 80 of 100 on the final, that's 80%. This calculator uses that percentage, weighted by the final's share of your course grade, to find what you need." ], [ "What if my final is worth 20%?", "With a 20% final weight, the final can move your grade by up to 20 points on the 100-point scale. To raise an 82 average to a 90, you'd need: required = (90 − 82 × 0.80) ÷ 0.20 = (90 − 65.6) ÷ 0.20 = 122%, which is unreachable — so even a perfect final wouldn't get you to 90. Lower weights mean the final has less leverage." ], [ "What grade do I need on my final to get an A?", "Enter your current average, the final's weight, and the A threshold (typically 90%) as your desired grade. The calculator returns the exact final score you need. For example, to reach 90% with an 82 average and a 20% final weight, you'd need 122% — impossible, meaning a lower target or extra credit is required." ], [ "What happens if the required score is over 100?", "The target is unreachable from your current position — the calculator shows the best possible course grade instead." ], [ "How does the final's weight affect the math?", "Higher weight means the final moves your grade more; the same desired grade needs a lower score on a heavier final." ], [ "Is this the same as my school's grade calculator?", "The formula is standard weighted-average math; your school's rounding and extra-credit policies can shift the result." ], [ "Can I use it if my teacher curves the final?", "No — a curve changes the scoring; use the tool on the uncurved numbers and adjust for the curve after." ] ] }, { "slug": "five-number-summary-calculator", "name": "Five Number Summary Calculator", "canonical_url": "https://boringtoolskit.com/five-number-summary-calculator/", "category": "Statistics", "description": "Five number summary calculator: min, quartiles, median, max, IQR and outliers.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "fix-and-flip-profit-calculator", "name": "Fix and Flip Profit Calculator", "canonical_url": "https://boringtoolskit.com/fix-and-flip-profit-calculator/", "category": "Finance & Investing", "description": "Project full profit on a fix-and-flip. Enter purchase, rehab, holding and selling costs, and after-repair value.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/after-repair-value-calculator/", "/maximum-allowable-offer-calculator/", "/rental-property-roi-calculator/" ], "answer": "Project full profit on a fix-and-flip. Enter purchase, rehab, holding and selling costs, and after-repair value.", "formula": "Fix-and-flip profit = sale price (or after-repair value) − purchase price − rehabilitation cost − holding costs − closing costs. The result is the expected profit after all expenses.", "example": "A flip purchased at $180,000, with $40,000 rehab, $8,000 holding, $9,000 closing, sold at $280,000, yields a profit of $280,000 − $180,000 − $40,000 − $8,000 − $9,000 = $43,000.", "assumptions": [ "Profit is sale price minus all entered costs.", "The tool supports using an after-repair value or an entered sale price.", "Holding and closing costs are user estimates." ], "sources": [ { "organization": "Investopedia", "title": "Fix and Flip", "url": "https://www.investopedia.com/terms/f/fix-and-flip.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate fix-and-flip profit?", "Profit = sale price − purchase price − rehab cost − holding costs − closing costs." ], [ "What costs should I include?", "All of them: purchase, rehab, holding (mortgage, insurance, utilities), closing/transfer, and any financing (hard money) interest." ], [ "What is a good flip profit margin?", "Many investors target an overall return of 20%+ on the money invested. A common absolute rule is at least $25,000–$30,000 profit to make it worth the risk." ], [ "Why do flips fail?", "Usually from overpaying, overestimating ARV, or underestimating rehab and holding time. The profit math is unforgiving of a too-high purchase." ], [ "Should I use a conservative sale price?", "Yes — model near the low end of the comp range. If it only works at an optimistic sale price, the deal is too risky." ], [ "Does this include financing costs?", "Only if you enter them. For a hard-money flip, add the loan interest and fees as a holding/other cost." ], [ "Is profit the same as ROI?", "No. Profit is the absolute dollar gain. ROI is profit ÷ money you put in. Both matter — use the margin to compare deals." ] ] }, { "slug": "flash-guide-number-calculator", "name": "Flash Guide Number Calculator", "canonical_url": "https://boringtoolskit.com/flash-guide-number-calculator/", "category": "Photo & Video", "description": "Flash guide number calculator: solve guide number, aperture, or distance for flash photography.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "flight-carbon-footprint-calculator", "name": "Flight Carbon Footprint Calculator", "canonical_url": "https://boringtoolskit.com/flight-carbon-footprint-calculator/", "category": "Everyday Calculators", "description": "Flight carbon footprint calculator: estimated CO2 per passenger for a flight, by distance and cabin class.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "flight-delay-compensation-calculator", "name": "Flight Delay Compensation Calculator", "canonical_url": "https://boringtoolskit.com/flight-delay-compensation-calculator/", "category": "Travel", "description": "Flight delay compensation calculator: EU261 compensation for delayed flights by distance.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "flooring-calculator", "name": "Flooring Calculator", "canonical_url": "https://boringtoolskit.com/flooring-calculator/", "category": "Construction & Measurement", "description": "Estimate flooring area, waste allowance, and boxes required for a room.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/square-footage-calculator/", "/tile-calculator/", "/paint-coverage-calculator/", "/research/construction-waste-factor-scenarios/" ], "answer": "Construction material waste and overage: estimate flooring area, user-selected overage, and full boxes. The entered overage is not a universal waste factor.", "formula": "Room area = length × width. Area with waste = room area × (1 + waste%). Boxes required = ceil(area with waste ÷ box coverage). Purchased coverage = boxes × box coverage.", "example": "A 12 × 15 ft room is 180 sq ft. At 10% waste that's 198 sq ft. With 20 sq ft per box, you need ceil(198 ÷ 20) = 10 boxes, covering 200 sq ft.", "assumptions": [ "The room is rectangular.", "Waste percentage is entered by the user.", "Boxes are rounded up to whole numbers." ], "sources": [ { "organization": "CalculatorSoup", "title": "Square Footage Calculator", "url": "https://www.calculatorsoup.com/calculators/construction/square-footage-calculator.php" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate flooring for a room?", "Multiply the room length by the width to get square feet, add a waste allowance (usually 10%), then divide by the coverage per box and round up." ], [ "How much waste should I add?", "10% is standard for rectangular rooms with straight layouts. Diagonal patterns, herringbone, or rooms with many cuts can need 15–20%." ], [ "What is box coverage?", "The square footage a box of flooring covers, printed on the product. Divide your total area by it to find how many boxes to buy." ], [ "Can I buy less than a full box?", "No — flooring comes in whole boxes. Always round up, and keep spare planks for future repairs." ], [ "What about closets and alcoves?", "Measure them separately and add their area to the room total. The calculator assumes one rectangle; split irregular layouts into rectangles." ], [ "Should I measure in feet or inches?", "Feet with decimals works best (12 ft 6 in = 12.5 ft). Convert inches to feet by dividing by 12." ], [ "Why is my estimate different from the store's?", "Different waste assumptions, box coverages, or measuring conventions. Confirm the product's exact coverage and add your own waste factor." ], [ "How much flooring do I need?", "Room area ÷ coverage per box, plus 5–15% waste by layout." ], [ "How many square feet in a box?", "Laminate/vinyl commonly 15–25 sq ft; check the product label." ], [ "Do I need underlayment?", "Usually yes — budget it separately from the flooring." ] ] }, { "slug": "focal-length-calculator", "name": "Focal Length Calculator", "canonical_url": "https://boringtoolskit.com/focal-length-calculator/", "category": "Photo & Video", "description": "Focal length calculator: estimate focal length from sensor width, subject distance, and field-of-view width.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "folder-to-prompt", "name": "Folder to Prompt", "canonical_url": "https://boringtoolskit.com/folder-to-prompt/", "category": "Text & Developer Tools", "description": "Turn a local project folder into a structured AI prompt without uploading its files.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/word-counter/", "/readability/", "/csv-to-json/" ], "answer": "Turn a local project folder into a structured AI prompt without uploading its files.", "formula": "Bundles selected folder files into a single prompt text with file paths, skipping binary files and security-sensitive paths (.git, node_modules, .env, credentials, keys).", "example": "Selecting a small project folder with README.md and src/app.py produces a prompt containing both files labeled by path — ready to paste into an AI tool.", "assumptions": [ "The user reviews output before sharing it.", "Security-blocked paths cover common secret files.", "Binary files are excluded from the bundle." ], "sources": [ { "organization": "Wikipedia", "title": "Prompt engineering", "url": "https://en.wikipedia.org/wiki/Prompt_engineering" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What does folder to prompt do?", "It packages the text files in a selected folder into a single prompt with file paths — ready for an AI coding assistant." ], [ "What files are skipped?", "Binary files and security-sensitive paths: .git, node_modules, .env, credentials, secret files, and private keys." ], [ "Is my code uploaded?", "The bundling runs locally — but pasting the result into an AI tool sends it there. Review before pasting." ], [ "Why is it useful?", "AI models give better answers with real context — the actual code and structure beat a verbal description." ], [ "What if my folder is huge?", "The prompt becomes very long — select only the relevant files to keep it focused and within model limits." ], [ "Can I use it for documentation?", "Yes — bundle docs and specs for summarization or review tasks." ], [ "Is it safe for secrets?", "Common secret files are filtered automatically, but always review the output before sharing it anywhere." ] ] }, { "slug": "follower-growth-calculator", "name": "Follower Growth Calculator", "canonical_url": "https://boringtoolskit.com/follower-growth-calculator/", "category": "Social Media", "description": "Project follower growth from starting audience, growth rate, and timeline.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/engagement-rate-calculator/", "/post-frequency-calculator/", "/social-media-earnings-calculator/" ], "answer": "Project follower growth from starting audience, growth rate, and timeline.", "formula": "Projected followers = current × (1 + monthly growth rate ÷ 100)^months. Net gain = projected − current.", "example": "10,000 followers growing 4% a month for 12 months: projected = 10,000 × (1.04)^12 = 16,010, a gain of 6,010 (60.1%).", "assumptions": [ "The growth rate is applied monthly and compounds.", "Growth is assumed steady; real accounts fluctuate and may plateau.", "The projection is forward-looking, not a guarantee." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "food-cost-calculator", "name": "Food Cost Calculator", "canonical_url": "https://boringtoolskit.com/food-cost-calculator/", "category": "Food & Cooking", "description": "Food cost calculator: ingredient cost per serving and food-cost percentage for menu pricing.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "food-safety-temperature-calculator", "name": "Food Safety Temperature Calculator", "canonical_url": "https://boringtoolskit.com/food-safety-temperature-calculator/", "category": "Food & Cooking", "description": "Food safety temperature calculator: safe internal temperatures.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "food-storage-time-calculator", "name": "Food Storage Time Calculator", "canonical_url": "https://boringtoolskit.com/food-storage-time-calculator/", "category": "Food & Cooking", "description": "Food storage time guide: safe refrigerator and freezer storage times for common foods.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "force-calculator", "name": "Force Calculator", "canonical_url": "https://boringtoolskit.com/force-calculator/", "category": "Physics", "description": "Calculate force, mass, or acceleration using Newton's second law (F = ma).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/momentum-calculator/", "/acceleration-calculator/", "/work-power-calculator/" ], "answer": "Calculate force, mass, or acceleration using Newton's second law (F = ma).", "formula": "Force (F) = mass × acceleration. Units: newtons (N) = kg · m/s².", "example": "A 12 kg cart accelerates at 3 m/s². Force = 12 × 3 = 36 N.", "assumptions": [ "Mass is in kilograms and acceleration in m/s².", "The calculation assumes a constant, net force with no friction.", "Positive values are required for both inputs." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "fps-sensitivity-converter", "name": "FPS Sensitivity Converter", "canonical_url": "https://boringtoolskit.com/fps-sensitivity-converter/", "category": "Gaming", "description": "FPS sensitivity converter: convert mouse sensitivity between games and calculate eDPI and cm/360.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "fraction-operations-calculator", "name": "Fraction Operations Calculator", "canonical_url": "https://boringtoolskit.com/fraction-operations-calculator/", "category": "Everyday Calculators", "description": "Fraction operations calculator: add, subtract, multiply, divide fractions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-27", "related_urls": [], "answer": "Fraction operations calculator: add, subtract, multiply, divide fractions.", "formula": "a/b + c/d = (ad + bc)/(bd); multiply: (a/b) × (c/d) = ac/bd.", "example": "1/2 + 1/3 = 3/6 + 2/6 = 5/6.", "assumptions": [ "Standard geometric or arithmetic definitions apply.", "Inputs use the units you choose.", "Results are estimates, not professional advice." ], "sources": [ { "organization": "Standard mathematics definitions", "title": "Arithmetic and geometry formulas", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "fraction-simplify-calculator", "name": "Simplify Fractions Calculator", "canonical_url": "https://boringtoolskit.com/fraction-simplify-calculator/", "category": "Everyday Calculators", "description": "Reduce any fraction to lowest terms with the GCD shown, plus decimal and mixed-number forms.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/fractions-calculator/", "/rounding-numbers-calculator/", "/order-of-operations-calculator/" ], "answer": "Reduce any fraction to lowest terms with the GCD shown, plus decimal and mixed-number forms.", "formula": "Simplifies a fraction by dividing numerator and denominator by their greatest common divisor (GCD).", "example": "12/18 simplifies to 2/3 (dividing both by 6).", "assumptions": [ "The fraction is proper or improper but valid.", "The denominator is not zero.", "Simplest form uses positive integers." ], "sources": [ { "organization": "Wikipedia", "title": "Fraction", "url": "https://en.wikipedia.org/wiki/Fraction" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I simplify a fraction?", "Divide top and bottom by their GCD: 12 ÷ 6 / 18 ÷ 6 = 2/3." ], [ "What is the GCD?", "The greatest common divisor — the largest number that divides both values." ], [ "What is the simplest form?", "A fraction where the numerator and denominator share no common factor other than 1." ], [ "Can I simplify mixed numbers?", "Convert to an improper fraction first, then simplify." ], [ "What if the denominator is zero?", "The fraction is undefined — the tool flags it." ], [ "Does it show the decimal?", "Yes — the simplified form comes with its decimal value." ], [ "Why simplify at all?", "Simplest form is easier to read, compare, and use in further math." ] ] }, { "slug": "fraction-to-decimal-calculator", "name": "Fraction to Decimal Calculator", "canonical_url": "https://boringtoolskit.com/fraction-to-decimal-calculator/", "category": "School & Education", "description": "Fraction to decimal calculator: numerator over denominator as a decimal and percent.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "fractions-calculator", "name": "Fractions Calculator", "canonical_url": "https://boringtoolskit.com/fractions-calculator/", "category": "Everyday Calculators", "description": "Add, subtract, multiply, or divide two fractions and get the simplified result.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/gcf-lcm-calculator/", "/fraction-simplify-calculator/", "/exponent-calculator/" ], "answer": "Add, subtract, multiply, or divide two fractions and get the simplified result.", "formula": "Add: (n1×d2 + n2×d1) ÷ (d1×d2). Subtract: (n1×d2 − n2×d1) ÷ (d1×d2). Multiply: (n1×n2) ÷ (d1×d2). Divide: (n1×d2) ÷ (d1×n2). The result is simplified by dividing numerator and denominator by their greatest common divisor.", "example": "1/2 + 1/3 = (1×3 + 1×2) ÷ (2×3) = 5/6 ≈ 0.8333.", "assumptions": [ "Neither denominator is zero.", "Inputs are integers (whole-number numerators and denominators).", "Results are reduced to lowest terms." ], "sources": [ { "organization": "Math Is Fun", "title": "Fractions", "url": "https://www.mathsisfun.com/fractions.html" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I add fractions?", "Multiply the first numerator by the second denominator and vice versa, add, then divide by the product of the denominators: (n1×d2 + n2×d1) ÷ (d1×d2)." ], [ "How do I divide fractions?", "Multiply the first fraction by the reciprocal of the second: (n1×d2) ÷ (d1×n2)." ], [ "What is simplifying a fraction?", "Dividing the numerator and denominator by their greatest common factor so the fraction is in lowest terms (e.g., 4/6 → 2/3)." ], [ "Why can't a denominator be zero?", "Division by zero is undefined in mathematics — a fraction with a zero denominator has no value." ], [ "What is an improper fraction?", "A fraction where the numerator is larger than the denominator (e.g., 7/4). This tool shows it as-is rather than converting to a mixed number." ], [ "How do I convert a fraction to a decimal?", "Divide the numerator by the denominator. The tool shows this alongside the simplified fraction." ], [ "What is a common denominator?", "A shared multiple of both denominators that lets you add or subtract fractions directly. This tool uses the product of the two denominators." ] ] }, { "slug": "frame-rate-duration-calculator", "name": "Frame Rate Duration Calculator", "canonical_url": "https://boringtoolskit.com/frame-rate-duration-calculator/", "category": "Photo & Video", "description": "Frame rate duration calculator: convert frames to seconds, minutes, or timecode at any frames-per-second rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "frame-size-calculator", "name": "Frame Size Calculator", "canonical_url": "https://boringtoolskit.com/frame-size-calculator/", "category": "Health", "description": "Frame size calculator: small, medium, or large body frame from wrist.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "freelance-hourly-rate-calculator", "name": "Freelance Hourly Rate Calculator", "canonical_url": "https://boringtoolskit.com/freelance-hourly-rate-calculator/", "category": "Seller & Business", "description": "Estimate a sustainable freelance hourly rate from income goals, expenses, taxes, and billable hours.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/salary-hourly-converter/", "/paycheck-calc/", "/overtime-calculator/" ], "answer": "Estimate a sustainable freelance hourly rate from income goals, expenses, taxes, and billable hours.", "formula": "Required gross = (target take-home ÷ (1 − tax rate)) + business expenses. Hourly rate = required gross ÷ (weeks worked × hours per week × billable %).", "example": "Target $60,000 take-home, 25% tax, $2,000 expenses, 48 weeks × 40 hrs at 80% billable: gross ≈ $82,000 → hourly ≈ $53.39.", "assumptions": [ "Taxes are estimated at the entered rate.", "Expenses are annual and fixed.", "Billable % reflects real utilization." ], "sources": [ { "organization": "Wikipedia", "title": "Freelancer", "url": "https://en.wikipedia.org/wiki/Freelancer" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I set my freelance rate?", "Work backward: target take-home ÷ (1−tax) + expenses = gross, then ÷ billable hours. $82,000 ÷ 1,536 billable hrs ≈ $53/hr." ], [ "What is billable utilization?", "The share of your work hours you can charge — 80% is realistic because admin and marketing eat the rest." ], [ "What tax rate should I use?", "25–35% is a common planning range for US self-employed income (income + self-employment tax)." ], [ "Should I include benefits?", "Yes — health insurance, retirement, and paid time off should be built into expenses or margin." ], [ "How is this different from an employee salary?", "Employees get benefits and paid time off; freelancers cover those themselves — that's why freelance rates run higher than hourly equivalents." ], [ "What if my rate is above market?", "Cut expenses, raise billable utilization, specialize, or accept a lower take-home — the calculator makes the trade-off visible." ], [ "How often should I reprice?", "Annually, or when expenses, taxes, or your income target change." ], [ "How many hours are billable?", "Typically 50–80% of working hours; the rest is admin, marketing, and unpaid work." ], [ "What taxes do freelancers pay?", "Income tax plus self-employment tax — often 25–40% of gross." ] ] }, { "slug": "frequency-to-note-calculator", "name": "Frequency to Note Converter", "canonical_url": "https://boringtoolskit.com/frequency-to-note-calculator/", "category": "Music & Audio", "description": "Convert a sound frequency to its closest musical note with cents deviation.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/bpm-to-ms-calculator/", "/scale-finder-calculator/", "/key-transposition-calculator/" ], "answer": "Convert a sound frequency to its closest musical note with cents deviation.", "formula": "MIDI note = round(12 × log₂(freq ÷ 440)) + 69. Note name from the 12-note chromatic set. Detuning in cents = 1200 × log₂(freq ÷ 440) − 1200 × (MIDI − 69).", "example": "For 440 Hz: MIDI = 69, which is A4, 0 cents. For 466 Hz: MIDI ≈ 70 (A#4), roughly 16 cents sharp.", "assumptions": [ "Frequency must be positive.", "The reference is A4 = 440 Hz standard tuning.", "The nearest note is the closest 12-tone equal-tempered pitch." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "fsa-calculator", "name": "FSA Calculator", "canonical_url": "https://boringtoolskit.com/fsa-calculator/", "category": "Finance & Investing", "description": "FSA calculator: tax savings and what you risk with use-it-or-lose-it.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "fuel-cost-per-mile-calculator", "name": "Fuel Cost Per Mile Calculator", "canonical_url": "https://boringtoolskit.com/fuel-cost-per-mile-calculator/", "category": "Vehicles", "description": "Fuel cost per mile calculator: cost per mile and per month from MPG and fuel price.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "fuel-trip-cost-calculator", "name": "Fuel & Trip Cost Calculator", "canonical_url": "https://boringtoolskit.com/fuel-trip-cost-calculator/", "category": "Everyday Calculators", "description": "Estimate fuel used, total trip cost, and each traveler’s share in MPG or L/100 km mode.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/ev-charging-cost-calculator/", "/electricity-cost-calculator/", "/gas-mileage-calculator/" ], "answer": "Estimate fuel used, total trip cost, and each traveler’s share in MPG or L/100 km mode.", "formula": "Fuel used = distance ÷ efficiency (MPG) or distance ÷ 100 × L/100km. Cost = fuel used × price. The tool splits the cost per traveler and per trip.", "example": "A 300-mile trip at 30 MPG uses 10 gallons — $35.00 at $3.50/gallon.", "assumptions": [ "Efficiency is the user's real-world number.", "Fuel price is per gallon or per liter as entered.", "No tolls or other trip costs are included." ], "sources": [ { "organization": "Wikipedia", "title": "Fuel economy in automobiles", "url": "https://en.wikipedia.org/wiki/Fuel_economy_in_automobiles" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate fuel cost for a trip?", "Distance ÷ MPG × price: 300 miles ÷ 30 × $3.50 = $35." ], [ "What MPG should I use?", "Your vehicle's real observed MPG — the dashboard average, which beats the EPA sticker for planning." ], [ "Does it handle metric?", "Yes — the tool supports L/100km and liters." ], [ "How do I split costs with passengers?", "The tool divides the total by travelers — a 4-person trip costs each a quarter." ], [ "Why is my actual cost higher?", "Traffic, speed, AC, and load all cut efficiency; fuel prices also vary by station." ], [ "Is an EV cheaper?", "Run both through the calculators — EVs typically cost less per mile at home rates, but public fast charging narrows the gap." ], [ "Does this include tolls?", "No — it's fuel only. Add tolls, parking, and wear separately." ], [ "How do I estimate fuel cost?", "Distance ÷ mpg × price per gallon." ], [ "Should I use the sticker mpg?", "No — use your observed average; real-world efficiency is lower." ], [ "How does an EV compare?", "Use miles per kWh and charging rate — often cheaper per mile than gas." ], [ "Should I add a buffer?", "15–20% for detours, traffic, and load is a realistic planning margin." ] ] }, { "slug": "furnace-size-calculator", "name": "Furnace Size Calculator", "canonical_url": "https://boringtoolskit.com/furnace-size-calculator/", "category": "Energy & Electrical", "description": "Furnace size calculator: BTU and tonnage from square footage.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "future-value-calculator", "name": "Future Value Calculator", "canonical_url": "https://boringtoolskit.com/future-value-calculator/", "category": "Finance & Investing", "description": "Project the future value of a starting balance and recurring monthly contributions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/retirement-planning-calculator/", "/savings-goal-calculator/", "/cagr-calculator/" ], "answer": "Project the future value of a starting balance and recurring monthly contributions.", "formula": "Future value is calculated month by month: balance grows by annual rate ÷ 12, with deposits applied at the selected timing.", "example": "", "assumptions": [ "Rate and contributions remain constant.", "Taxes, fees, and market volatility are excluded.", "This is a hypothetical projection, not an investment forecast." ], "sources": [ { "organization": "Investor.gov", "title": "Compound interest calculator", "url": "https://www.investor.gov/financial-tools-calculators/calculators/compound-interest-calculator" }, { "organization": "SEC", "title": "Saving and investing roadmap", "url": "https://www.sec.gov/investor/pubs/sec-guide-to-savings-and-investing.pdf" } ], "faqs": [ [ "What is a future value calculator and how does it work?", "A future value calculator estimates how much your current investment will be worth over time based on compound interest. You simply enter your initial amount, contribution frequency, interest rate, and time period to get an instant projection." ], [ "Do I need to create an account or sign up to use this future value calculator?", "No, this is a completely no-signup tool. It runs entirely in your browser, so your data is never stored on a server or shared with anyone." ], [ "How accurate are the results from this future value calculator?", "The results are mathematically accurate based on the inputs you provide, assuming a constant interest rate. However, it does not account for taxes, inflation, or fluctuating market returns, so it is best used for general planning rather than exact financial predictions." ] ] }, { "slug": "g-force-calculator", "name": "G Force Calculator", "canonical_url": "https://boringtoolskit.com/g-force-calculator/", "category": "Physics", "description": "G force calculator: cornering acceleration from speed and radius.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "gacha-pity-calculator", "name": "Gacha Pity Calculator", "canonical_url": "https://boringtoolskit.com/gacha-pity-calculator/", "category": "Gaming", "description": "Gacha pity calculator: honest odds of pulling the featured item within N pulls.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "garage-size-calculator", "name": "Garage Size Calculator", "canonical_url": "https://boringtoolskit.com/garage-size-calculator/", "category": "Construction & Measurement", "description": "Garage size calculator: minimum dimensions by car count.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "gas-budget-calculator", "name": "Gas Budget Calculator", "canonical_url": "https://boringtoolskit.com/gas-budget-calculator/", "category": "Vehicles", "description": "Gas budget calculator: monthly and yearly fuel spending.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "gas-laws-calculator", "name": "Gas Laws Calculator", "canonical_url": "https://boringtoolskit.com/gas-laws-calculator/", "category": "Chemistry", "description": "Apply Boyle's, Charles', and the Ideal Gas Law to gas properties.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/equilibrium-constants-calculator/", "/molarity-calculator/", "/stoichiometry-calculator/" ], "answer": "Apply Boyle's, Charles', and the Ideal Gas Law to gas properties.", "formula": "Ideal gas law: PV = nRT with R = 0.08206 L·atm/(mol·K). Temperature is converted from °C to K (T = °C + 273.15). Leave one of P, V, n, T blank.", "example": "For 1 mol of gas at 273.15 K in 22.4 L: P = nRT ÷ V = (1 × 0.08206 × 273.15) ÷ 22.4 ≈ 1 atm.", "assumptions": [ "R = 0.08206 L·atm/(mol·K); pressure is in atm and volume in L.", "Temperature is entered in °C and converted to Kelvin.", "The ideal gas law assumes ideal behavior; real gases deviate at high pressure or low temperature." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "gas-mileage-calculator", "name": "Gas Mileage Calculator", "canonical_url": "https://boringtoolskit.com/gas-mileage-calculator/", "category": "Everyday Calculators", "description": "Calculate miles per gallon or liters per 100 km from distance and fuel used.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/fuel-trip-cost-calculator/", "/electricity-cost-calculator/", "/currency-conv/" ], "answer": "Calculate miles per gallon or liters per 100 km from distance and fuel used.", "formula": "US: MPG = miles ÷ gallons. Metric: L/100km = (liters ÷ km) × 100. Mixed units are converted (1 mile = 1.60934 km, 1 US gallon = 3.78541 L).", "example": "300 miles on 10 gallons = 30 MPG. Or 40 liters for 500 km = 8.0 L/100km.", "assumptions": [ "The tank was full at both ends of the measurement.", "US gallons are used for MPG.", "The driving is a representative mix." ], "sources": [ { "organization": "U.S. Department of Energy", "title": "fueleconomy.gov", "url": "https://www.fueleconomy.gov/" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate MPG?", "Divide miles driven by gallons used: 300 miles ÷ 10 gallons = 30 MPG." ], [ "What is L/100km?", "Liters of fuel per 100 kilometers — the metric fuel economy. 8 L/100km means the car uses 8 liters to drive 100 km." ], [ "How do I measure it accurately?", "Fill the tank completely, reset the trip odometer, drive, then refill to full and divide the miles by the gallons pumped." ], [ "What's a good MPG?", "It depends on the vehicle: 30+ MPG is good for a car, 15–20 for a truck or SUV. Compare against the vehicle's EPA rating." ], [ "Does driving style matter?", "Yes — rapid acceleration, speeding, and idling cut MPG significantly. Smooth driving and proper tire pressure help." ], [ "What's the difference between US and imperial gallons?", "An imperial gallon is larger (4.546 L vs 3.785 L). MPG figures differ between the two — the tool uses US gallons." ], [ "How do I estimate trip cost?", "Divide the trip distance by your MPG and multiply by the fuel price. The fuel trip cost calculator does this directly." ] ] }, { "slug": "gcf-lcm-calculator", "name": "GCF and LCM Calculator", "canonical_url": "https://boringtoolskit.com/gcf-lcm-calculator/", "category": "Everyday Calculators", "description": "Find the greatest common factor and least common multiple of two numbers.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/fractions-calculator/", "/fraction-simplify-calculator/", "/exponent-calculator/" ], "answer": "Find the greatest common factor and least common multiple of two numbers.", "formula": "Greatest common factor (GCF) via the Euclidean algorithm: repeatedly replace (x, y) with (y, x mod y) until y = 0; the last x is the GCF. Least common multiple: LCM = a × b ÷ GCF(a, b).", "example": "For 12 and 18: GCF = 6 (12 = 2²×3, 18 = 2×3²), LCM = 12 × 18 ÷ 6 = 36.", "assumptions": [ "Both inputs are positive integers.", "Standard definitions of GCF and LCM apply.", "Results are exact integers." ], "sources": [ { "organization": "Math Is Fun", "title": "Greatest Common Factor", "url": "https://www.mathsisfun.com/greatest-common-factor.html" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is the greatest common factor (GCF)?", "The largest number that divides both inputs exactly. For 12 and 18, the GCF is 6." ], [ "What is the least common multiple (LCM)?", "The smallest positive number that both inputs divide exactly. For 12 and 18, the LCM is 36." ], [ "How is the GCF computed?", "With the Euclidean algorithm: keep replacing the pair (x, y) with (y, x mod y) until y = 0; the remaining x is the GCF. It's fast and exact." ], [ "How is the LCM related to the GCF?", "LCM(a, b) = a × b ÷ GCF(a, b). If you know one, you can compute the other." ], [ "Why use the GCF?", "To simplify fractions: divide numerator and denominator by their GCF to get lowest terms (e.g., 12/18 → 2/3)." ], [ "Why use the LCM?", "To add or subtract fractions with different denominators, or to find when repeating events coincide (e.g., every 4 days and every 6 days → every 12 days)." ], [ "Do GCF and LCM work for more than two numbers?", "Yes, by applying them pairwise: GCF(a, b, c) = GCF(GCF(a, b), c), and likewise for LCM." ], [ "What is the GCF?", "The largest number that divides both inputs — 6 for 12 and 18." ], [ "What is the LCM?", "The smallest number both divide into — 36 for 12 and 18." ], [ "How are they related?", "LCM × GCF = a × b for two numbers." ], [ "What are they used for?", "Simplifying fractions (GCF) and aligning schedules or denominators (LCM)." ] ] }, { "slug": "gdp-calculator", "name": "GDP Calculator", "canonical_url": "https://boringtoolskit.com/gdp-calculator/", "category": "Finance & Investing", "description": "GDP calculator: gross domestic product from consumption, investment, government, and net exports.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "general-scientific-calculator", "name": "General and Scientific Calculator", "canonical_url": "https://boringtoolskit.com/general-scientific-calculator/", "category": "Everyday Calculators", "description": "Use a fast general calculator or switch on scientific functions for trigonometry, logarithms, powers, roots, memory, and calculation history.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/percentage-calc/", "/statistics-calculator/", "/hex-to-decimal/" ], "answer": "Use a fast general calculator or switch on scientific functions for trigonometry, logarithms, powers, roots, memory, and calculation history.", "formula": "A full scientific calculator with arithmetic, parentheses, powers and roots, trigonometric functions (sin/cos/tan with degree or radian mode), logarithms, constants, and memory.", "example": "sin(30°) = 0.5; 2^10 = 1024; log10(100) = 2.", "assumptions": [ "Standard operator precedence applies.", "The angle mode matches the user's intent.", "Floating-point rounding is expected." ], "sources": [ { "organization": "Wikipedia", "title": "Scientific calculator", "url": "https://en.wikipedia.org/wiki/Scientific_calculator" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What functions does it have?", "Arithmetic, powers, roots, trig (sin/cos/tan), logarithms, constants (π, e), memory, and full parentheses." ], [ "Why is sin(30) showing −0.99?", "Your angle mode is radians — in radians, sin(30) ≈ −0.99. In degrees, sin(30) = 0.5." ], [ "How do I switch between degrees and radians?", "Use the angle mode toggle — degrees for most geometry, radians for calculus and physics." ], [ "How do I enter powers?", "Use the power key or ^: 2^10 = 1024." ], [ "Does it follow order of operations?", "Yes — standard precedence with parentheses for grouping." ], [ "Can I use memory?", "Yes — store, recall, and clear values with the memory keys." ], [ "Why do results have tiny rounding errors?", "Floating-point arithmetic — normal for all calculators (sin(30°) can show as 0.4999999...)." ] ] }, { "slug": "generator-load-calculator", "name": "Generator Load Calculator", "canonical_url": "https://boringtoolskit.com/generator-load-calculator/", "category": "Energy & Electrical", "description": "Generator load calculator: wattage needed for appliances.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "generator-runtime-calculator", "name": "Generator Runtime Calculator", "canonical_url": "https://boringtoolskit.com/generator-runtime-calculator/", "category": "Energy & Electrical", "description": "Generator runtime calculator: hours on a tank of fuel.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "generator-size-calculator", "name": "Generator Size Calculator", "canonical_url": "https://boringtoolskit.com/generator-size-calculator/", "category": "Construction & Measurement", "description": "Generator size calculator: watts needed for running loads plus starting surge.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "geographic-area-calculator", "name": "Geographic Area Calculator", "canonical_url": "https://boringtoolskit.com/geographic-area-calculator/", "category": "Geography", "description": "Geographic area calculator: approximate rectangle area on the globe from corner coordinates.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "geometric-distribution-calculator", "name": "Geometric Distribution Calculator", "canonical_url": "https://boringtoolskit.com/geometric-distribution-calculator/", "category": "Statistics", "description": "Geometric distribution calculator: first success on trial k.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "geometric-mean-calculator", "name": "Geometric and Harmonic Mean Calculator", "canonical_url": "https://boringtoolskit.com/geometric-mean-calculator/", "category": "Statistics", "description": "Geometric and harmonic mean calculator: multiplicative-average measures for rates, ratios, and growth data.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "geometric-sequence-calculator", "name": "Geometric Sequence Calculator", "canonical_url": "https://boringtoolskit.com/geometric-sequence-calculator/", "category": "School & Education", "description": "Geometric sequence calculator: nth term and sum from first term and ratio.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "gestational-age-calculator", "name": "Gestational Age Calculator", "canonical_url": "https://boringtoolskit.com/gestational-age-calculator/", "category": "Health", "description": "Gestational age calculator: weeks pregnant and due date from last period.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "gfr-calculator", "name": "GFR Calculator", "canonical_url": "https://boringtoolskit.com/gfr-calculator/", "category": "Health", "description": "eGFR calculator (CKD-EPI 2021): estimated kidney filtration rate from creatinine, age, and sex.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "gift-tax-calculator", "name": "Gift Tax Calculator", "canonical_url": "https://boringtoolskit.com/gift-tax-calculator/", "category": "Finance & Investing", "description": "Gift tax calculator: taxable gifts above the annual exclusion.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "glove-size-calculator", "name": "Glove Size Calculator", "canonical_url": "https://boringtoolskit.com/glove-size-calculator/", "category": "Converters", "description": "Glove size calculator: S/M/L/XL from hand circumference.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "gold-silver-precious-metals", "name": "Gold, Silver & Precious Metals Price Calculator", "canonical_url": "https://boringtoolskit.com/gold-silver-precious-metals/", "category": "Finance & Investing", "description": "Live gold, silver, platinum, and palladium spot prices plus a precious-metals and rare-earth element lookup with atomic numbers, weights, and uses.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/currency-conv/", "/inflation-impact-calculator/", "/unit-conv/" ], "answer": "Live gold, silver, platinum, and palladium spot prices plus a precious-metals and rare-earth element lookup with atomic numbers, weights, and uses.", "formula": "Value = weight × purity × spot price per unit. The tool converts between troy ounces and grams (1 troy oz = 31.1034768 g) and applies the metal's fineness (24k gold = 99.9% pure, 18k = 75%) to live spot prices.", "example": "At a $2,400/oz gold spot, 1 troy oz of 24k gold is worth about $2,400; 10 g of 18k gold is worth about 10 × 0.75 × $77.16 ≈ $578.71.", "assumptions": [], "sources": [ { "organization": "World Gold Council", "title": "Gold prices and data", "url": "https://www.gold.org/goldhub/data/gold-prices" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a gold price calculator and how does it work?", "A gold price calculator is a free browser-based tool that estimates the value of gold, silver, and other precious metals based on real-time spot prices. Simply enter the weight, purity, and quantity of your item, and the calculator instantly returns an estimated market value, no signup or download required." ], [ "Do I need to create an account or provide personal information to use this gold price calculator?", "No. This gold price calculator is entirely no-signup and private. It runs directly in your browser, meaning no data is sent to a server, no account is needed, and your calculations remain completely on your device." ], [ "How accurate are the results from this gold price calculator?", "The calculator provides estimated values based on current live spot prices for gold, silver, and other precious metals. Accuracy depends on the spot price data source and the purity/weight you input. It is a helpful planning tool but should not be considered a definitive appraisal, actual resale or buyback prices may vary by dealer." ], [ "What does purity or fineness mean?", "Purity is the share of the metal in the item: 24k gold is 99.9% pure, 18k is 75%, 14k is 58.5%. The value scales directly with purity — 18k gold is worth 75% of the same weight of 24k." ], [ "What is a troy ounce?", "The standard precious-metal weight: 1 troy oz = 31.1034768 grams (vs 28.35 g for a regular ounce). Gold and silver prices are quoted per troy ounce." ], [ "Why is the retail price higher than spot?", "Spot is the wholesale metal price. Retail items add premiums for fabrication, design, and dealer margin — so a coin or jewelry piece sells above its melt value." ], [ "How often do the prices update?", "The tool pulls live spot prices from its data source when you calculate, so the estimate reflects the latest available quote. Real market prices move continuously during trading hours." ], [ "Is this financial advice?", "No. The calculator values metal by weight and spot price only; it's a reference tool, not a recommendation to buy, sell, or hold any metal." ] ] }, { "slug": "golden-ratio-calculator", "name": "Golden Ratio Calculator", "canonical_url": "https://boringtoolskit.com/golden-ratio-calculator/", "category": "Everyday Calculators", "description": "Golden ratio calculator: phi times a number.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-27", "related_urls": [], "answer": "Golden ratio calculator: phi times a number.", "formula": "φ ≈ 1.61803, defined by (a + b)/a = a/b = φ.", "example": "A 1.618 m by 1 m rectangle follows the golden ratio.", "assumptions": [ "Standard geometric or arithmetic definitions apply.", "Inputs use the units you choose.", "Results are estimates, not professional advice." ], "sources": [ { "organization": "Standard mathematics definitions", "title": "Arithmetic and geometry formulas", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "golf-club-distance-calculator", "name": "Golf Club Distance Calculator", "canonical_url": "https://boringtoolskit.com/golf-club-distance-calculator/", "category": "Sports", "description": "Golf club distance calculator: driver distance from swing speed.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "golf-handicap-calculator", "name": "Golf Handicap Calculator", "canonical_url": "https://boringtoolskit.com/golf-handicap-calculator/", "category": "Sports", "description": "Golf handicap calculator: handicap index from score, course rating, and slope.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "gpa-calculator", "name": "GPA Calculator", "canonical_url": "https://boringtoolskit.com/gpa-calculator/", "category": "School & Education", "description": "Calculate your GPA on a standard 4.0 scale from course letter grades and credits. Local, private, no upload.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/grade-calculator/", "/final-exam-calculator/", "/percentage-calc/" ], "answer": "Calculate your GPA on a standard 4.0 scale from course letter grades and credits. Local, private, no upload.", "formula": "GPA = Σ (grade points × course credits) ÷ Σ credits. Standard scale: A = 4.0, A− = 3.7, B+ = 3.3, B = 3.0, B− = 2.7, C+ = 2.3, C = 2.0, C− = 1.7, D+ = 1.3, D = 1.0, D− = 0.7, F = 0.0.", "example": "An A (4.0) in a 3-credit course and a B (3.0) in another 3-credit course: (4.0×3 + 3.0×3) ÷ 6 = 3.50 GPA.", "assumptions": [ "The standard 4.0 plus/minus scale is used.", "All courses are unweighted.", "Credits are entered as the school defines them." ], "sources": [ { "organization": "Wikipedia", "title": "Academic grading in the United States", "url": "https://en.wikipedia.org/wiki/Academic_grading_in_the_United_States" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How is GPA calculated?", "Sum of (grade points × credits) divided by total credits. An A (4.0) in 3 credits + a B (3.0) in 3 credits = (12 + 9) ÷ 6 = 3.50." ], [ "What are grade points?", "The numeric value of each grade: A = 4.0, A− = 3.7, B+ = 3.3, B = 3.0, B− = 2.7, C+ = 2.3, C = 2.0, C− = 1.7, D+ = 1.3, D = 1.0, D− = 0.7, F = 0.0." ], [ "Why do credits matter?", "A 4-credit course counts more than a 2-credit one — GPA is credit-weighted, not a simple average of grades." ], [ "What is an unweighted GPA?", "Standard 4.0 scale with no bonus for honors/AP classes. Weighted GPAs add points for advanced courses." ], [ "Is the plus/minus scale universal?", "No — many schools use plain A/B/C without pluses and minuses. Adjust to your school's scale." ], [ "What GPA do I need?", "It depends on your goals: 3.0 for many programs, 3.5+ for competitive ones, and academic standing requirements vary." ], [ "How can I improve my GPA?", "Focus on high-credit courses (they move the average more), retake failed courses where allowed, and raise grades in your weakest classes." ] ] }, { "slug": "grade-calculator", "name": "Test Grade Calculator", "canonical_url": "https://boringtoolskit.com/grade-calculator/", "category": "School & Education", "description": "Convert test points into a percentage and letter grade, and see the points needed for the next grade up.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/gpa-calculator/", "/final-exam-calculator/", "/percentage-calc/" ], "answer": "Convert test points into a percentage and letter grade, and see the points needed for the next grade up.", "formula": "Percentage = (points earned ÷ points possible) × 100. Letter grade from the standard scale: A ≥ 90, B ≥ 80, C ≥ 70, D ≥ 60, F < 60. The tool also shows points needed for the next letter grade.", "example": "85 points earned out of 100 possible = 85% = a B; 5 more points would reach an A (90%).", "assumptions": [ "The standard 90/80/70/60 letter scale applies.", "Points are weighted equally.", "No curve or plus/minus adjustments are applied." ], "sources": [ { "organization": "Wikipedia", "title": "Grading in education", "url": "https://en.wikipedia.org/wiki/Grading_in_education" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate my grade?", "Divide points earned by points possible and multiply by 100: 85/100 = 85% = B." ], [ "What is the letter grade scale?", "Standard: A ≥ 90, B ≥ 80, C ≥ 70, D ≥ 60, F < 60. Some courses use plus/minus or different cutoffs." ], [ "How many points do I need for an A?", "The tool shows it: from 85%, you need 5 more points (to 90%) on a 100-point scale." ], [ "Does this work for weighted courses?", "Only if all assignments are equal weight. Weighted grades need each component's weight applied separately." ], [ "What about curved grades?", "Curves adjust scores after the raw calculation — enter your curved score if you have it." ], [ "How do I find my overall grade?", "Calculate each assignment's percentage, then average them (or apply weights). This tool handles single assignments." ], [ "What is a passing grade?", "Typically 60% (D) or higher, but programs and institutions vary." ], [ "Do the weights matter?", "Yes — a 90 on a 5% quiz moves less than a 75 on a 40% exam." ], [ "What do I need on the final?", "The calculator returns the required score from your target grade." ], [ "Should weights sum to 100?", "Yes — the gradebook's weights must total 100%." ] ] }, { "slug": "grade-percentage-calculator", "name": "Grade Percentage Calculator", "canonical_url": "https://boringtoolskit.com/grade-percentage-calculator/", "category": "Construction & Measurement", "description": "Grade percentage calculator: slope as percent and degrees.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "grams-to-cups-calculator", "name": "Grams to Cups Calculator", "canonical_url": "https://boringtoolskit.com/grams-to-cups-calculator/", "category": "Food & Cooking", "description": "Grams to cups calculator: weight to volume by ingredient density.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "gravel-calculator", "name": "Gravel Calculator", "canonical_url": "https://boringtoolskit.com/gravel-calculator/", "category": "Construction & Measurement", "description": "Estimate gravel volume, weight, waste, and optional material cost for a rectangular area.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/mulch-soil-calculator/", "/concrete-calculator/", "/paver-calculator/" ], "answer": "Estimate gravel volume, weight, waste, and optional material cost for a rectangular area.", "formula": "Cubic feet = length × width × depth ÷ 12; cubic yards = cubic feet ÷ 27; tons = cubic feet × density ÷ 2,000.", "example": "", "assumptions": [ "The area is rectangular and depth is uniform.", "Bulk density is editable because material type and moisture vary.", "Waste does not model compaction separately unless included in the allowance." ], "sources": [ { "organization": "NIST", "title": "Handbook 44 tables and units", "url": "https://www.nist.gov/pml/owm/nist-handbook-44-current-edition" }, { "organization": "USGS", "title": "Mineral commodity information", "url": "https://www.usgs.gov/centers/national-minerals-information-center" } ], "faqs": [ [ "What is a gravel calculator?", "A gravel calculator estimates the volume and weight of gravel needed for a project based on dimensions and depth. It's a free, browser-based tool with no signup required." ], [ "How do I use the gravel calculator?", "Enter the length, width, and desired depth, then select gravel type to get the amount. The tool calculates instantly and shows results in cubic yards, cubic feet, and tons." ], [ "Do I need to create an account?", "No, the gravel calculator operates entirely in your browser without any signup. It's designed for quick, anonymous estimates." ] ] }, { "slug": "grip-strength-calculator", "name": "Grip Strength Calculator", "canonical_url": "https://boringtoolskit.com/grip-strength-calculator/", "category": "Sports", "description": "Grip strength calculator: handgrip rating by age and gender.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "gross-margin-calculator", "name": "Gross Margin Calculator", "canonical_url": "https://boringtoolskit.com/gross-margin-calculator/", "category": "Finance & Investing", "description": "Gross margin calculator: profit margin and markup from revenue and cost of goods sold.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "gross-rent-multiplier-calculator", "name": "Gross Rent Multiplier Calculator", "canonical_url": "https://boringtoolskit.com/gross-rent-multiplier-calculator/", "category": "Finance & Investing", "description": "Calculate the gross rent multiplier (GRM). Enter property price and annual rent for the 10-second income screen.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/rental-yield-calculator/", "/price-to-rent-ratio-calculator/", "/cap-rate-calculator/" ], "answer": "Calculate the gross rent multiplier (GRM). Enter property price and annual rent for the 10-second income screen.", "formula": "Gross rent multiplier (GRM) = property price ÷ annual rent. A lower GRM means a higher income yield relative to price — a faster way to compare investment properties by price-to-income.", "example": "A property priced at $300,000 with $24,000 in annual rent has a GRM of $300,000 ÷ $24,000 = 12.5.", "assumptions": [ "Annual gross rent is monthly rent × 12.", "GRM uses gross rent — no operating costs, no financing.", "Comparing GRMs across different markets can be misleading." ], "sources": [ { "organization": "Investopedia", "title": "Gross Rent Multiplier", "url": "https://www.investopedia.com/terms/g/gross-rent-multiplier.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a good gross rent multiplier?", "It varies by market. Many investors target a GRM under 15; a lower GRM generally means better income value relative to price." ], [ "How do I calculate GRM?", "GRM = property price ÷ annual gross rent (monthly rent × 12)." ], [ "What does a lower GRM mean?", "More rent income per dollar of purchase price — generally a better value, though it can also signal a lower-cost or riskier market." ], [ "Does GRM include expenses?", "No. GRM uses gross rent before vacancy, taxes, insurance, maintenance, and management. Use cap rate or cash flow for the net picture." ], [ "How is GRM different from cap rate?", "GRM uses gross rent; cap rate uses net operating income. Cap rate is the more accurate profitability measure; GRM is the faster screening ratio." ], [ "Can I value a property with GRM?", "Yes, roughly: value ≈ target GRM × annual rent. If you target a GRM of 10 and the property rents for $24,000/year, it's worth about $240,000 to you." ], [ "Why does GRM vary so much by location?", "Because property prices and rents don't move proportionally. High-price, high-rent cities and low-price, low-rent rural markets have very different GRMs." ] ] }, { "slug": "gross-up-calculator", "name": "Gross Up Calculator", "canonical_url": "https://boringtoolskit.com/gross-up-calculator/", "category": "Finance & Investing", "description": "Gross up calculator: convert a net pay or budget target to gross pay including taxes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "grout-calculator", "name": "Grout Calculator", "canonical_url": "https://boringtoolskit.com/grout-calculator/", "category": "Construction & Measurement", "description": "Grout calculator: pounds of grout for a tile job.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "gumroad-fee-calculator", "name": "Gumroad Fee Calculator", "canonical_url": "https://boringtoolskit.com/gumroad-fee-calculator/", "category": "Seller & Business", "description": "Gumroad fee calculator: the 10% creator fee plus payment processing.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "gutter-size-calculator", "name": "Gutter Size Calculator", "canonical_url": "https://boringtoolskit.com/gutter-size-calculator/", "category": "Construction & Measurement", "description": "Gutter size calculator: 5-inch or 6-inch gutter by roof area.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "gym-cost-per-visit-calculator", "name": "Gym Cost Per Visit Calculator", "canonical_url": "https://boringtoolskit.com/gym-cost-per-visit-calculator/", "category": "Health", "description": "Gym cost per visit calculator: is your membership actually worth it?", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "half-life-calculator", "name": "Half Life Calculator", "canonical_url": "https://boringtoolskit.com/half-life-calculator/", "category": "Physics", "description": "Half life calculator: remaining amount after elapsed time with a known half-life.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "hardy-weinberg-calculator", "name": "Hardy Weinberg Calculator", "canonical_url": "https://boringtoolskit.com/hardy-weinberg-calculator/", "category": "Biology", "description": "Hardy Weinberg calculator: genotype frequencies from allele frequency under equilibrium.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "harmonic-mean-calculator", "name": "Harmonic Mean Calculator", "canonical_url": "https://boringtoolskit.com/harmonic-mean-calculator/", "category": "Statistics", "description": "Harmonic mean calculator: n divided by the sum of reciprocals.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "hashtag-performance-calculator", "name": "Hashtag Performance Calculator", "canonical_url": "https://boringtoolskit.com/hashtag-performance-calculator/", "category": "Social Media", "description": "Measure hashtag reach, impressions, and engagement rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/engagement-rate-calculator/", "/instagram-influencer-pricing-calculator/", "/post-frequency-calculator/" ], "answer": "Measure hashtag reach, impressions, and engagement rate.", "formula": "Hashtag engagement rate = (hashtag engagement ÷ hashtag reach) × 100. Average engagement per post = engagement ÷ posts.", "example": "2,400 engagements on 240,000 reach across 12 posts: rate = 2,400 ÷ 240,000 × 100 = 1.00%, averaging 200 engagements per post.", "assumptions": [ "Reach and engagement are totals across the posts entered.", "Engagement is measured the same way for every post.", "Hashtag performance varies by topic and platform." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "hat-size-calculator", "name": "Hat Size Calculator", "canonical_url": "https://boringtoolskit.com/hat-size-calculator/", "category": "Converters", "description": "Hat size calculator: US hat size from head circumference.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "heart-rate-recovery-calculator", "name": "Heart Rate Recovery Calculator", "canonical_url": "https://boringtoolskit.com/heart-rate-recovery-calculator/", "category": "Health", "description": "Heart rate recovery calculator: HR drop after exercise.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "heart-rate-zones-calculator", "name": "Heart Rate Zones Calculator", "canonical_url": "https://boringtoolskit.com/heart-rate-zones-calculator/", "category": "Health", "description": "Heart rate zones calculator: target training zones from age and resting heart rate, computed locally.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "heat-index-calculator", "name": "Heat Index Calculator", "canonical_url": "https://boringtoolskit.com/heat-index-calculator/", "category": "Everyday Calculators", "description": "Calculate the apparent (feels-like) temperature from air temperature and humidity.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/weather-lookup/", "/us-weather-forecast/", "/daily-hydration-calculator/" ], "answer": "Calculate the apparent (feels-like) temperature from air temperature and humidity.", "formula": "Heat index (NWS regression, valid for T ≥ 80°F and RH ≥ 40%): HI = −42.379 + 2.04901523×T + 10.14333127×RH − 0.22475541×T×RH − 0.00683783×T² − 0.05481717×RH² + 0.00122874×T²×RH + 0.00085282×T×RH² − 0.00000199×T²×RH². Below those thresholds, HI = T.", "example": "At 90°F with 60% relative humidity, the heat index is about 100°F — the temperature it feels like when humidity slows evaporative cooling.", "assumptions": [ "The NWS heat-index regression is used.", "Conditions are in the shade.", "Temperature is in Fahrenheit." ], "sources": [ { "organization": "National Weather Service", "title": "Heat Index", "url": "https://www.weather.gov/ama/heatindex" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is the heat index?", "The apparent temperature — how hot it feels when relative humidity is factored in with the air temperature. Humidity reduces sweat evaporation, making it feel hotter." ], [ "How is it calculated?", "The National Weather Service uses a regression formula based on temperature and relative humidity, valid above 80°F and 40% humidity. Below those, the heat index equals the air temperature." ], [ "Why is humidity important?", "Your body cools by evaporating sweat. High humidity slows evaporation, so the same temperature feels hotter and is harder on your body." ], [ "When is heat index dangerous?", "NWS categories: 90–103°F caution, 103–124°F danger (cramps and heat exhaustion likely), 125°F+ extreme danger (heat stroke possible)." ], [ "Does direct sun matter?", "Yes — the heat index is for shade. Direct sunlight can add up to 15°F to the feels-like temperature." ], [ "Does wind change it?", "Wind helps evaporative cooling at moderate temperatures, but the standard heat index doesn't include it — the wind chill index is the cold-weather counterpart." ], [ "Is heat index the same as feels-like temperature?", "Roughly — 'feels like' in weather apps often combines heat index (summer) or wind chill (winter) with other factors." ] ] }, { "slug": "hectare-acre-converter", "name": "Hectare to Acre Converter", "canonical_url": "https://boringtoolskit.com/hectare-acre-converter/", "category": "Converters", "description": "Hectare to acre converter: hectares, acres, square meters.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "heloc-calculator", "name": "HELOC Calculator", "canonical_url": "https://boringtoolskit.com/heloc-calculator/", "category": "Everyday Calculators", "description": "Estimate the monthly payment and total cost of a home equity line of credit.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/mortgage-afford/", "/mortgage-payment-calculator/", "/loan-to-value-calculator/" ], "answer": "Estimate the monthly payment and total cost of a home equity line of credit.", "formula": "Interest-only payment = balance × monthly rate (APR ÷ 12). Amortizing payment = balance × r ÷ (1 − (1 + r)^−n), where r is the monthly rate and n the months remaining after the draw period.", "example": "A $50,000 HELOC at 8% with a 10-year term and 5-year draw: interest-only payment = $50,000 × 0.006667 ≈ $333.33/month. After the draw, the balance amortizes over 60 months at about $1,013.82/month.", "assumptions": [ "The rate stays constant at the entered APR.", "During the draw you pay interest only, with no principal reduction.", "Repayment uses a fixed-rate amortization over the remaining months." ], "sources": [ { "organization": "Investopedia", "title": "Home Equity Line of Credit (HELOC)", "url": "https://www.investopedia.com/terms/h/home_equity_line_of_credit.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a HELOC?", "A home equity line of credit is a revolving credit line secured by your home. You draw what you need during the draw period, then repay over the remaining term." ], [ "How is a HELOC different from a home equity loan?", "A home equity loan is a lump sum with fixed payments; a HELOC is a revolving line you draw as needed, usually with variable rates and interest-only payments during the draw." ], [ "Why does the payment jump?", "During the draw period you pay interest only. When repayment begins, you must also repay principal, so the monthly payment rises significantly." ], [ "Are HELOC rates fixed or variable?", "Most are variable — they track an index (like the prime rate) plus a margin. Your rate and payment can rise when rates rise." ], [ "Is HELOC interest tax deductible?", "Under current rules, interest is deductible only if the loan is used to buy, build, or substantially improve the home. Confirm with a tax professional for your situation." ], [ "What is loan-to-value and why does it matter?", "LTV = loan balance ÷ home value. Lenders typically cap your combined LTV (mortgage + HELOC) at 80–90%, so your available credit depends on your home's value and existing mortgage." ], [ "What happens if I can't repay?", "The HELOC is secured by your home, so defaulting can lead to foreclosure. Only borrow against equity you can confidently repay." ] ] }, { "slug": "herons-formula-calculator", "name": "Heron's Formula Calculator", "canonical_url": "https://boringtoolskit.com/herons-formula-calculator/", "category": "Everyday Calculators", "description": "Heron's formula calculator: triangle area from three sides.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "hex-to-cmyk-converter", "name": "Hex to CMYK Converter", "canonical_url": "https://boringtoolskit.com/hex-to-cmyk-converter/", "category": "Colors & Design", "description": "Hex to CMYK converter: convert a #RRGGBB hex color to CMYK values for print.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "hex-to-decimal", "name": "Hex to Decimal Converter", "canonical_url": "https://boringtoolskit.com/hex-to-decimal/", "category": "Converters", "description": "Convert hexadecimal and decimal values with an interactive positional-value explanation.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/base64-tool/", "/scientific-notation-converter/", "/unit-conv/" ], "answer": "Convert hexadecimal and decimal values with an interactive positional-value explanation.", "formula": "Hex to decimal: each digit's place value is a power of 16 (rightmost = 16⁰). Decimal to hex: repeatedly divide by 16 and record remainders. Colors (#RRGGBB) convert to 24-bit integers.", "example": "0xFF = 15×16 + 15 = 255. #FFFFFF = 255×65536 + 255×256 + 255 = 16,777,215.", "assumptions": [ "Hex input uses digits 0–9 and A–F.", "The 0x prefix and # are optional.", "Values stay within safe integer range." ], "sources": [ { "organization": "Wikipedia", "title": "Hexadecimal", "url": "https://en.wikipedia.org/wiki/Hexadecimal" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I convert hex to decimal?", "Sum each digit × 16^position: 0xFF = 15×16 + 15 = 255." ], [ "What is hexadecimal?", "Base-16 notation using digits 0–9 and A–F, where each position is a power of 16. It's the standard way computers display binary data compactly." ], [ "How do I convert decimal to hex?", "Repeatedly divide by 16 and read the remainders from last to first: 255 → FF." ], [ "Why is hex used in computing?", "One hex digit = 4 bits, two = 1 byte, so it's a compact human-readable form of binary — ideal for colors, addresses, and dumps." ], [ "How do colors convert?", "#RRGGBB is three bytes: #FFFFFF = 255×65536 + 255×256 + 255 = 16,777,215." ], [ "Is the # or 0x prefix required?", "No — the tool accepts plain hex digits, with or without a prefix." ], [ "What is a MAC address?", "A 48-bit hardware address usually written as 6 hex bytes (00:1A:2B:3C:4D:5E) — hex makes it readable." ] ] }, { "slug": "hex-to-hsl-converter", "name": "Hex to HSL Converter", "canonical_url": "https://boringtoolskit.com/hex-to-hsl-converter/", "category": "Colors & Design", "description": "Hex to HSL converter: convert a hex color to HSL values and CSS string.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "hex-to-rgb", "name": "HEX to RGB Converter", "canonical_url": "https://boringtoolskit.com/hex-to-rgb/", "category": "Everyday Calculators", "description": "Convert any hex color code to its red, green, and blue (RGB) values instantly, in the browser.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/color-picker/", "/hex-to-decimal/", "/contrast-ratio-calculator/" ], "answer": "Convert any hex color code to its red, green, and blue (RGB) values instantly, in the browser.", "formula": "Splits a hex color into its red, green, and blue bytes: #RRGGBB → (RR₁₆, GG₁₆, BB₁₆) in decimal (0–255). 3-digit shorthand expands each digit.", "example": "#2563eb = rgb(37, 99, 235) — the blue-600 Tailwind color.", "assumptions": [ "The hex code is valid (#RRGGBB or shorthand).", "The conversion targets CSS rgb().", "No alpha channel is modeled." ], "sources": [ { "organization": "Wikipedia", "title": "Web colors", "url": "https://en.wikipedia.org/wiki/Web_colors" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I convert hex to RGB?", "Split the code into three pairs and convert each from hex to decimal: #2563eb = rgb(37, 99, 235)." ], [ "What is the # format?", "Six hex digits, two per channel: #RRGGBB. Each channel ranges 00–FF (0–255)." ], [ "What is 3-digit shorthand?", "#fff expands to #ffffff by doubling each digit — shorthand for colors with repeated pairs." ], [ "What's the difference from hex to decimal?", "The hex-to-decimal tool converts a single number; this converts a color code into its three channel values." ], [ "How do I use the rgb() value?", "Paste it directly into CSS: background: rgb(37, 99, 235);" ], [ "Does it handle alpha/opacity?", "No — for alpha use rgba() or the 8-digit hex form." ], [ "How do I check if the color passes contrast?", "Use the contrast ratio calculator with the background color." ] ] }, { "slug": "hexagon-calculator", "name": "Hexagon Calculator", "canonical_url": "https://boringtoolskit.com/hexagon-calculator/", "category": "Everyday Calculators", "description": "Hexagon calculator: area and perimeter of a regular hexagon.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "hiking-time-calculator", "name": "Hiking Time Calculator", "canonical_url": "https://boringtoolskit.com/hiking-time-calculator/", "category": "Sports", "description": "Hiking time calculator: Naismith\\u2019s rule for distance and elevation gain.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "holiday-pay-calculator", "name": "Holiday Pay Calculator", "canonical_url": "https://boringtoolskit.com/holiday-pay-calculator/", "category": "Time & Work", "description": "Holiday pay calculator: time-and-a-half and double-time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "home-equity-calculator", "name": "Home Equity Calculator", "canonical_url": "https://boringtoolskit.com/home-equity-calculator/", "category": "Real Estate", "description": "Home equity calculator: your equity stake and loan-to-value ratio.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "horsepower-calculator", "name": "Horsepower Calculator", "canonical_url": "https://boringtoolskit.com/horsepower-calculator/", "category": "Vehicles", "description": "Horsepower calculator: horsepower from torque and RPM (torque × RPM ÷ 5252).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "horsepower-kw-converter", "name": "Horsepower to kW Converter", "canonical_url": "https://boringtoolskit.com/horsepower-kw-converter/", "category": "Converters", "description": "Horsepower to kW converter: hp and kilowatts.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "hotel-stay-cost-calculator", "name": "Hotel Stay Cost Calculator", "canonical_url": "https://boringtoolskit.com/hotel-stay-cost-calculator/", "category": "Travel", "description": "Hotel stay cost calculator: total trip hotel cost including taxes and resort fees, with per-person split.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "hours-minutes-calculator", "name": "Hours and Minutes Calculator", "canonical_url": "https://boringtoolskit.com/hours-minutes-calculator/", "category": "Time & Work", "description": "Add or subtract hours and minutes and show decimal-hour equivalents.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/time-card-calculator/", "/overtime-calculator/", "/date-difference-calculator/" ], "answer": "Add or subtract hours and minutes and show decimal-hour equivalents.", "formula": "Converts each time to total minutes (hours × 60 + minutes), performs the addition or subtraction, then converts back to hours and minutes.", "example": "3 hours 45 minutes + 2 hours 30 minutes = 6 hours 15 minutes.", "assumptions": [ "Values are durations, not clock times.", "The 60-minute hour convention applies.", "No date or midnight crossing is modeled." ], "sources": [ { "organization": "Wikipedia", "title": "Hour", "url": "https://en.wikipedia.org/wiki/Hour" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I add hours and minutes?", "Add the minutes, carry every 60 as an hour: 3:45 + 2:30 = 6:15." ], [ "Why isn't 90 minutes 1.9 hours?", "Time is base-60: 90 minutes = 1 hour 30 minutes." ], [ "Can it subtract?", "Yes — subtract mode works for any pair of durations." ], [ "What happens if the result is negative?", "It shows a minus sign — subtracting a longer duration from a shorter one." ], [ "Does it cross midnight?", "No — the tool works on durations. For clock times across midnight, use the time card calculator." ], [ "How do I total many entries?", "Add them in pairs, or use the time card calculator for daily work totals." ], [ "How do I convert to decimal hours for payroll?", "Divide minutes by 60: 6:15 = 6.25 hours. Many payroll systems use decimals." ] ] }, { "slug": "hp-to-weight-ratio-calculator", "name": "HP to Weight Ratio Calculator", "canonical_url": "https://boringtoolskit.com/hp-to-weight-ratio-calculator/", "category": "Vehicles", "description": "Horsepower-to-weight calculator: power-to-weight in hp/lb and hp/ton for any car.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "hsa-tax-savings-calculator", "name": "HSA Tax Savings Calculator", "canonical_url": "https://boringtoolskit.com/hsa-tax-savings-calculator/", "category": "Finance & Investing", "description": "HSA tax savings calculator: what an HSA contribution saves you in federal income tax.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "humidity-index-calculator", "name": "Humidity Index Calculator", "canonical_url": "https://boringtoolskit.com/humidity-index-calculator/", "category": "Geography", "description": "Humidity index calculator: humidex feels-like value from temperature and dew point.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "ideal-weight-calculator", "name": "Ideal Weight Calculator", "canonical_url": "https://boringtoolskit.com/ideal-weight-calculator/", "category": "Health", "description": "Estimate your ideal body weight using seven common formulas (Hamwi, Devine, Robinson, Miller, Broca, Lorentz, Peterson) plus a healthy BMI range.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/bmi-calc/", "/bmr-tdee-calculator/", "/calories-burned-calculator/" ], "answer": "Estimate your ideal body weight using seven common formulas (Hamwi, Devine, Robinson, Miller, Broca, Lorentz, Peterson) plus a healthy BMI range.", "formula": "The tool reports the healthy BMI weight range (18.5–24.9 × height²) plus classic adult formulas in kg: Hamwi (male 48.0 + 2.7×in-over-60; female 45.5 + 2.2×in-over-60), Devine (male 50.0 + 2.3×in-over-60; female 45.5 + 2.3×in-over-60), Robinson (male 52.0 + 1.9×; female 49.0 + 1.7×), Miller (male 56.2 + 1.41×; female 53.1 + 1.36×), Broca (cm − 100), Lorentz ((cm − 100) − (cm − 150) ÷ (4 male / 2 female)), Peterson (2.2×targetBMI + 3.5×targetBMI×(heightM − 1.5)).", "example": "A 5'10\" (70 in, 177.8 cm) male: Devine ideal weight = 50.0 + 2.3×10 = 73 kg (161 lb); healthy BMI range = 18.5–24.9 × 1.778² ≈ 58–79 kg (128–174 lb).", "assumptions": [ "Height and sex are entered correctly.", "The formulas are population reference standards.", "Results are estimates, not medical advice." ], "sources": [ { "organization": "National Heart, Lung, and Blood Institute", "title": "Assessing Your Weight and Health Risk (BMI)", "url": "https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmicalc.htm" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a healthy weight for my height?", "The healthy BMI range (18.5–24.9) corresponds to a weight range for your height. For 5'10\", that's roughly 128–174 lb (58–79 kg)." ], [ "What is the Devine formula?", "Ideal weight = 50 kg + 2.3 kg per inch over 5 ft for men; 45.5 + 2.3 per inch over 5 ft for women. Originally developed for drug dosing." ], [ "Why do the formulas give different numbers?", "Each formula (Hamwi, Devine, Robinson, Miller, Broca, Lorentz) was derived from different populations and eras. The tool shows them all so you can see the range." ], [ "Is BMI an accurate health measure?", "It's a useful screening tool but ignores muscle mass and body composition. A muscular person can have a high BMI with low body fat." ], [ "What is a normal BMI?", "18.5–24.9 is the healthy range. Below 18.5 is underweight; 25–29.9 overweight; 30+ obese. The tool shows the weight range for the healthy BMI band." ], [ "Can I use this to set a weight-loss goal?", "Use it as a reference, but body composition and health markers matter more than a single formula number. A provider can help set a realistic target." ], [ "Does the tool account for muscle mass?", "No — these are height-and-sex formulas only. Muscle mass, frame size, and body fat aren't modeled." ], [ "How is ideal weight calculated?", "Formulas like Devine estimate from height; a BMI range of 18.5–24.9 is the broader healthy zone." ], [ "What is a healthy BMI?", "18.5–24.9 for most adults." ], [ "Why does the formula not fit athletes?", "Muscle mass raises weight without raising health risk — composition matters." ], [ "Is ideal weight a prescription?", "No — it is a population screen; individual health needs clinical context." ] ] }, { "slug": "idle-cost-calculator", "name": "Idle Cost Calculator", "canonical_url": "https://boringtoolskit.com/idle-cost-calculator/", "category": "Vehicles", "description": "Idle cost calculator: fuel wasted while idling.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "image-file-size-calculator", "name": "Image File Size Calculator", "canonical_url": "https://boringtoolskit.com/image-file-size-calculator/", "category": "Photo & Video", "description": "Image file size calculator: uncompressed size from pixel dimensions, bit depth, and color mode.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "image-resize", "name": "Image Resizer", "canonical_url": "https://boringtoolskit.com/image-resize/", "category": "Converters", "description": "Resize images without uploading to a server.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/pdf-to-jpg/", "/base64-tool/", "/qr-generator/" ], "answer": "Resize images without uploading to a server.", "formula": "Rescales an image to target dimensions with a chosen fit: exact (stretch to W×H), inside (fit within bounds, preserving aspect ratio), or cover (fill bounds, cropping excess).", "example": "A 1200×800 image resized to width 600 with aspect preserved becomes 600×400.", "assumptions": [ "The browser canvas API is available.", "The selected fit matches the intended use.", "The original image file is preserved by the user." ], "sources": [ { "organization": "Wikipedia", "title": "Image scaling", "url": "https://en.wikipedia.org/wiki/Image_scaling" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I resize an image?", "Upload it, enter the target width and height, choose the fit, and download — the tool processes it locally in your browser." ], [ "What do the fit modes do?", "Exact stretches to the dimensions; inside fits within them while keeping the aspect ratio; cover fills them and crops the excess." ], [ "Is my image uploaded?", "No — everything happens in your browser. Your picture never leaves your device." ], [ "Will enlarging make it blurry?", "Upscaling interpolates pixels but can't invent detail — small images get soft when enlarged. Start with the highest-resolution original." ], [ "What size should I use for the web?", "1200px wide is a good max for most layouts; keep file size under ~200 KB with JPEG quality settings." ], [ "Does resizing reduce quality?", "Downscaling loses detail permanently. Always keep the original file." ], [ "Can I resize to a specific file size?", "No — the tool controls dimensions, not compression. File size follows from resolution and format." ] ] }, { "slug": "inches-to-cm-converter", "name": "Inches to CM Converter", "canonical_url": "https://boringtoolskit.com/inches-to-cm-converter/", "category": "Converters", "description": "Inches to centimeters converter: inches to cm, mm, meters, and feet.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "independent-events-calculator", "name": "Independent Events Calculator", "canonical_url": "https://boringtoolskit.com/independent-events-calculator/", "category": "Statistics", "description": "Independent events calculator: probability both events happen.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "inductance-calculator", "name": "Inductance Calculator", "canonical_url": "https://boringtoolskit.com/inductance-calculator/", "category": "Energy & Electrical", "description": "Inductance calculator: inductance from inductive reactance and frequency.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "inflation-impact-calculator", "name": "Inflation Impact Calculator", "canonical_url": "https://boringtoolskit.com/inflation-impact-calculator/", "category": "Finance & Investing", "description": "Model future cost and purchasing-power erosion from an editable constant annual inflation assumption.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/compound-interest/", "/apr-effective-interest-calculator/", "/investment-return-calculator/" ], "answer": "Model future cost and purchasing-power erosion from an editable constant annual inflation assumption.", "formula": "Future cost = amount × (1 + rate)^years. Purchasing power = amount ÷ (1 + rate)^years. Price increase = amount × ((1 + rate)^years − 1).", "example": "$1,000 at 3% inflation for 20 years: future cost ≈ $1,806, so the purchasing power of $1,000 today falls to about $554.", "assumptions": [ "A constant inflation rate over the period.", "No interest or investment growth is modeled on the amount.", "The CPI-like average reflects the user's spending." ], "sources": [ { "organization": "Wikipedia", "title": "Inflation", "url": "https://en.wikipedia.org/wiki/Inflation" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is inflation?", "The general rise in prices over time, which reduces what each dollar can buy. It's usually measured by the Consumer Price Index (CPI)." ], [ "How do I calculate inflation's impact?", "Future cost = amount × (1 + rate)^years. $1,000 at 3% for 20 years costs about $1,806; its purchasing power falls to ~$554." ], [ "How fast does inflation halve money's value?", "At 3%, about 24 years (the rule of 72: 72 ÷ 3). At 6%, about 12 years." ], [ "What is purchasing power?", "What your money can actually buy — it falls as prices rise. $1,000 today buys less in the future at any positive inflation." ], [ "What's a 'real' return?", "Your investment return minus inflation: 7% nominal with 3% inflation is a 4% real gain." ], [ "Should I keep cash in a savings account?", "Cash that earns less than inflation loses real value — that's why long-term savings typically go into investments." ], [ "Is inflation always bad?", "Moderate inflation is normal in a growing economy; deflation (falling prices) has its own problems. The issue is when it outpaces your income and savings growth." ], [ "How does inflation affect my money?", "It reduces purchasing power: $10,000 at 3% inflation buys ~$13,400-worth in 10 years... or rather needs $13,400 to buy the same." ], [ "What is real return?", "Nominal return minus inflation — the actual growth in purchasing power." ], [ "How do I plan for inflation?", "Use real returns for long-term goals and category-specific rates where they apply." ], [ "Is 3% inflation a good assumption?", "It is the Fed's target; category rates can run higher for healthcare and education." ] ] }, { "slug": "instagram-influencer-pricing-calculator", "name": "Instagram Influencer Pricing Calculator", "canonical_url": "https://boringtoolskit.com/instagram-influencer-pricing-calculator/", "category": "Social Media", "description": "Calculate fair sponsored post rates from followers and engagement.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/engagement-rate-calculator/", "/hashtag-performance-calculator/", "/follower-growth-calculator/" ], "answer": "Calculate fair sponsored post rates from followers and engagement.", "formula": "Suggested post price = followers × (engagement rate ÷ 100) × rate per engagement.", "example": "50,000 followers at a 3% engagement rate and $0.50 per engagement: interactions = 1,500, price = 1,500 × 0.50 = $750.00.", "assumptions": [ "Engagement rate and rate-per-engagement are the user's inputs.", "The price is a suggestion for a single sponsored post.", "Deliverables (usage, exclusivity, story vs feed) often change actual pricing." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "insulation-calculator", "name": "Insulation R-Value Calculator", "canonical_url": "https://boringtoolskit.com/insulation-calculator/", "category": "Construction & Measurement", "description": "Insulation R-value calculator: U-value conversion and rough annual savings estimate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "insulation-r-value-calculator", "name": "Insulation R Value Calculator", "canonical_url": "https://boringtoolskit.com/insulation-r-value-calculator/", "category": "Construction & Measurement", "description": "Insulation R-value calculator: total R from layered materials.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "interest-only-loan-calculator", "name": "Interest Only Loan Calculator", "canonical_url": "https://boringtoolskit.com/interest-only-loan-calculator/", "category": "Finance & Investing", "description": "Interest-only loan calculator: IO payments then full amortization.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "interest-rate-calculator", "name": "Interest Rate Calculator", "canonical_url": "https://boringtoolskit.com/interest-rate-calculator/", "category": "Finance & Investing", "description": "Interest rate calculator: solve for the rate between present and future value.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "intermittent-fasting-calculator", "name": "Intermittent Fasting Calculator", "canonical_url": "https://boringtoolskit.com/intermittent-fasting-calculator/", "category": "Health", "description": "Intermittent fasting calculator: convert between eating windows and fasting hours.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "inventory-reorder-point-calculator", "name": "Inventory Reorder Point Calculator", "canonical_url": "https://boringtoolskit.com/inventory-reorder-point-calculator/", "category": "Seller & Business", "description": "Calculate your inventory reorder point: lead time demand plus safety stock, then see whether current stock means reorder now.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/cash-flow-runway-calculator/", "/break-even-units-calculator/", "/price-increase-impact-calculator/" ], "answer": "Calculate your inventory reorder point: lead time demand plus safety stock, then see whether current stock means reorder now.", "formula": "Reorder point = (average daily sales × lead time in days) + safety stock. Days of stock on hand = current stock ÷ average daily sales. Order now if current stock ≤ reorder point.", "example": "20 units sold per day, 7-day lead time, 40 units safety stock: reorder point = 20 × 7 + 40 = 180 units.", "assumptions": [ "Daily sales and lead time are reasonably stable.", "Safety stock is set appropriately by the user.", "No batch-discount or economic-order-quantity optimization is modeled." ], "sources": [ { "organization": "Wikipedia", "title": "Reorder point", "url": "https://en.wikipedia.org/wiki/Reorder_point" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a reorder point?", "The stock level that triggers a purchase order — lead-time demand plus safety stock. 20/day × 7 days + 40 = 180 units." ], [ "How do I calculate it?", "Average daily sales × lead time in days + safety stock. That's the level at which you place the next order." ], [ "What is safety stock?", "Extra inventory to cover demand spikes and supplier delays — a buffer sized to your risk tolerance." ], [ "What is lead time?", "The days between placing an order and receiving it. Longer lead times raise the reorder point." ], [ "What if my sales are seasonal?", "Use peak-season daily averages for holiday inventory, or recalculate the reorder point each season." ], [ "Why does overstocking hurt?", "Cash sits in shelves instead of working for you, and stock can go obsolete or expire." ], [ "How often should I review it?", "Quarterly, or whenever sales or lead times change materially." ], [ "How much safety stock should I carry?", "Enough to cover max-usage days beyond the average during lead time." ], [ "Does the reorder point change?", "Yes — as usage, lead time, or safety targets change, recompute the trigger." ] ] }, { "slug": "inverter-size-calculator", "name": "Inverter Size Calculator", "canonical_url": "https://boringtoolskit.com/inverter-size-calculator/", "category": "Energy & Electrical", "description": "Inverter size calculator: continuous and surge sizing.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "investment-fee-calculator", "name": "Investment Fee Calculator", "canonical_url": "https://boringtoolskit.com/investment-fee-calculator/", "category": "Finance & Investing", "description": "Investment fee calculator: the real cost of annual fees on long-term returns.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "investment-growth-calculator", "name": "Investment Growth Calculator", "canonical_url": "https://boringtoolskit.com/investment-growth-calculator/", "category": "Finance & Investing", "description": "Investment growth calculator: future value with monthly contributions and compound interest.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "investment-return-calculator", "name": "Investment Return Calculator", "canonical_url": "https://boringtoolskit.com/investment-return-calculator/", "category": "Everyday Calculators", "description": "Calculate total return and annualized (CAGR) return on an investment.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/compound-interest/", "/dca-investment-calculator/", "/stock-average-cost-calculator/" ], "answer": "Calculate total return and annualized (CAGR) return on an investment.", "formula": "Total return = (ending value − starting value) ÷ starting value × 100, including any cash flow contributed. The calculator compares a starting and ending value along with extra contributions to produce a return figure.", "example": "An investment of $10,000 that grows to $15,000 with $2,000 of extra contributions gives a total return of ($15,000 − $10,000 − $2,000) ÷ $10,000 = 30%.", "assumptions": [ "Extra contributions are added on top of the starting value.", "The return is over the full period, not annualized.", "Fees and taxes are not included unless entered as cash flow." ], "sources": [ { "organization": "Investopedia", "title": "Return on Investment", "url": "https://www.investopedia.com/terms/r/returnoninvestment.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate investment return?", "Total return = (ending value − starting value − extra contributions) ÷ starting value × 100." ], [ "What is a good return?", "It depends on your benchmark and time frame. Historically, broad stock index returns have averaged 7–10% annually, but that's nominal and not guaranteed." ], [ "Should I annualize my return?", "Yes, when comparing different time periods. A 30% return over 5 years is roughly 5.4% annualized; over 2 years it's ~14%." ], [ "Does this include dividends?", "Only if you count them as cash flow. For a true total return, add dividends and distributions received." ], [ "How do extra contributions affect return?", "They increase the value but aren't gains. The formula subtracts them so you measure performance, not just how much you added." ], [ "Why compare to inflation?", "Real return = nominal − inflation. A 7% return in a 4% inflation year is only 3% in purchasing power." ], [ "Is return the same as profit?", "Return is profit expressed as a percentage of what you invested. It standardizes gains so you can compare investments of different sizes." ] ] }, { "slug": "invoice-fee-calculator", "name": "Invoice Fee Calculator", "canonical_url": "https://boringtoolskit.com/invoice-fee-calculator/", "category": "Time & Work", "description": "Invoice fee calculator: net after payment processing fees.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "invoice-gen", "name": "Invoice Generator", "canonical_url": "https://boringtoolskit.com/invoice-gen/", "category": "Seller & Business", "description": "Create a simple invoice and download as PDF.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/quote-estimate-generator/", "/receipt-generator/", "/payment-terms-generator/" ], "answer": "Create a simple invoice and download as PDF.", "formula": "Line totals = quantity × unit price; subtotal = Σ line totals; tax = subtotal × tax rate; total = subtotal + tax. The tool renders a printable invoice and supports multiple currencies.", "example": "2 × $150 consulting hours = $300 subtotal; with 8% tax: $324 total.", "assumptions": [ "The user enters accurate business and client details.", "Line items are entered as description, qty, price.", "The tax rate is a flat percentage of the subtotal." ], "sources": [ { "organization": "Wikipedia", "title": "Invoice", "url": "https://en.wikipedia.org/wiki/Invoice" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I create an invoice?", "Add your business and client details, list line items (description, qty, price), set the tax rate, and generate — the tool computes subtotal, tax, and total." ], [ "What information should an invoice include?", "Your business name and contact, client details, invoice number and date, itemized lines, subtotal, tax, total, and payment terms." ], [ "How are line items calculated?", "Each line total = quantity × unit price; the subtotal is the sum; total = subtotal + tax." ], [ "Is the invoice legally valid?", "It's a working invoice document, but requirements vary by jurisdiction — include the tax IDs and details your tax authority requires." ], [ "Can I change the currency?", "Yes — the tool supports USD, EUR, GBP, CAD, AUD, and INR." ], [ "Does it track payments?", "No — this generates the document. Payment tracking and reminders need accounting software." ], [ "Can I save it as a PDF?", "Generate, then print or save to PDF from your browser." ] ] }, { "slug": "invoice-late-fee-calculator", "name": "Invoice Late Fee Calculator", "canonical_url": "https://boringtoolskit.com/invoice-late-fee-calculator/", "category": "Seller & Business", "description": "Estimate a simple or monthly-compounded late fee from invoice balance, rate, and overdue time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/invoice-gen/", "/simple-interest-calculator/", "/commission-calculator/" ], "answer": "Estimate a simple or monthly-compounded late fee from invoice balance, rate, and overdue time.", "formula": "Simple: fee = balance × monthly rate × (days late ÷ 30.4). Compound: balance × ((1 + monthly rate)^months − 1). Months = days ÷ 30.437 (average).", "example": "A $1,000 invoice 30 days late at 1.5% monthly: $1,000 × 1.5% = $15.00 in late fees.", "assumptions": [ "The rate is stated in the invoice terms.", "Days convert to months at 30.4 average days.", "Local law permits the charged rate." ], "sources": [ { "organization": "Wikipedia", "title": "Late fee", "url": "https://en.wikipedia.org/wiki/Late_fee" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate a late fee?", "Balance × monthly rate × months late: $1,000 × 1.5% × 1 = $15 for 30 days." ], [ "What is a standard late fee rate?", "1.5% monthly (18% annually) is common; many states cap fees or require them in the contract." ], [ "Is a late fee legal?", "Yes, if the rate is in the agreement and within state limits — check your jurisdiction." ], [ "What's the difference between simple and compound?", "Simple charges on the original balance; compound charges on the balance plus accumulated fees. Compound must be in the terms." ], [ "How do I convert days to months?", "Divide by 30.4 (the average month length) — the tool does this automatically." ], [ "Should I charge interest on late payments?", "It's standard practice for B2B — it compensates for the financing you're providing and speeds collections." ], [ "What if the client disputes?", "The written terms decide. Make the rate prominent on the invoice." ] ] }, { "slug": "iqr-calculator", "name": "IQR Calculator", "canonical_url": "https://boringtoolskit.com/iqr-calculator/", "category": "Statistics", "description": "IQR calculator: interquartile range from five values.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "irr-calculator", "name": "IRR Calculator", "canonical_url": "https://boringtoolskit.com/irr-calculator/", "category": "Everyday Calculators", "description": "Calculate the internal rate of return from a series of cash flows.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/present-value-calculator/", "/investment-return-calculator/", "/compound-interest/" ], "answer": "Calculate the internal rate of return from a series of cash flows.", "formula": "IRR is the discount rate r where the net present value of all cash flows equals zero: Σ cash_flow_t ÷ (1 + r)^t = 0. The tool solves for r by bisection between −99% and +1,000%.", "example": "An investment of −$10,000 followed by $3,000 per year for 4 years has an IRR of about 7.71% — the rate at which those inflows discount back to exactly $10,000.", "assumptions": [ "Cash flows occur at the end of each period.", "A single unique IRR exists (one sign change).", "Interim cash flows are reinvested at the computed IRR." ], "sources": [ { "organization": "Investopedia", "title": "Internal Rate of Return (IRR)", "url": "https://www.investopedia.com/terms/i/irr.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is IRR?", "Internal rate of return is the discount rate at which the net present value of an investment's cash flows equals zero — the annualized return implied by those cash flows." ], [ "How is IRR different from NPV?", "NPV gives a dollar value at your chosen discount rate; IRR gives a rate. Use NPV to compare projects and IRR to see whether a project clears your required return." ], [ "What is a good IRR?", "One that exceeds your cost of capital or required return. For example, if borrowing costs 8%, a project at 10% adds value; at 6% it destroys value versus the cost of funds." ], [ "Why does the tool say no unique IRR?", "IRR requires cash flows to start with an outflow and change sign only once. Multiple sign changes (like later negative years) can produce multiple IRRs or none." ], [ "Does IRR assume reinvestment?", "Yes — it assumes interim cash flows are reinvested at the same IRR, which is often optimistic. Modified IRR (MIRR) is a more conservative alternative." ], [ "What cash flows should I enter?", "The initial outlay as a negative number (e.g., -10000) and each expected inflow as a positive number, one per line, in period order." ], [ "Can IRR be negative?", "Yes — if inflows never repay the outlay, the rate that zeroes the NPV is negative, meaning the project loses money." ] ] }, { "slug": "jean-size-calculator", "name": "Jean Size Calculator", "canonical_url": "https://boringtoolskit.com/jean-size-calculator/", "category": "Converters", "description": "Jean size calculator: US to EU jean size conversion.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "jet-lag-calculator", "name": "Jet Lag Calculator", "canonical_url": "https://boringtoolskit.com/jet-lag-calculator/", "category": "Travel", "description": "Jet lag calculator: expected recovery days from time-zone difference and direction of travel.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "jetlag-adjustment-calculator", "name": "Jet Lag Adjustment Calculator", "canonical_url": "https://boringtoolskit.com/jetlag-adjustment-calculator/", "category": "Everyday Calculators", "description": "Jet lag adjustment calculator: estimated days to adjust after crossing time zones.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "json-formatter", "name": "JSON Formatter", "canonical_url": "https://boringtoolskit.com/json-formatter/", "category": "Text & Developer Tools", "description": "Format, validate, and pretty-print JSON instantly in your browser. Fix errors with a clear message and line pointer.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "kd-ratio-calculator", "name": "KD Ratio Calculator", "canonical_url": "https://boringtoolskit.com/kd-ratio-calculator/", "category": "Gaming", "description": "KD ratio calculator: kill/death ratio from kills, deaths, and matches played.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "kelly-criterion-calculator", "name": "Kelly Criterion Calculator", "canonical_url": "https://boringtoolskit.com/kelly-criterion-calculator/", "category": "Gaming", "description": "Kelly criterion calculator: optimal bet size from win probability and decimal odds.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "key-transposition-calculator", "name": "Key Transposition Calculator", "canonical_url": "https://boringtoolskit.com/key-transposition-calculator/", "category": "Music & Audio", "description": "Transpose music between keys by semitones for any instrument or vocal range.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/scale-finder-calculator/", "/frequency-to-note-calculator/", "/bpm-to-ms-calculator/" ], "answer": "Transpose music between keys by semitones for any instrument or vocal range.", "formula": "Semitone steps = (index of new key − index of old key + 12) mod 12, using the 12-note chromatic key set.", "example": "Transposing from C to D: (index 2 − index 0 + 12) mod 12 = 2, so up 2 semitones.", "assumptions": [ "Keys use standard names and enharmonic equivalents (e.g. C# vs Db).", "Transposition is measured in semitones from the original key.", "The calculation moves up by default (a positive step count)." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "keyword-density-calculator", "name": "Keyword Density Calculator", "canonical_url": "https://boringtoolskit.com/keyword-density-calculator/", "category": "Text & Developer Tools", "description": "Keyword density calculator: keyword share of a text.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "kinetic-energy-calculator", "name": "Kinetic Energy Calculator", "canonical_url": "https://boringtoolskit.com/kinetic-energy-calculator/", "category": "Physics", "description": "Calculate the kinetic energy of a moving object from mass and velocity (KE = ½mv²).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/momentum-calculator/", "/potential-energy-calculator/", "/work-power-calculator/" ], "answer": "Calculate the kinetic energy of a moving object from mass and velocity (KE = ½mv²).", "formula": "Kinetic energy (KE) = ½ × mass × velocity². Units: joules (J) = kg · m²/s².", "example": "A 2 kg object moving at 5 m/s: KE = ½ × 2 × 5² = 25 J.", "assumptions": [ "Mass is in kilograms and velocity in m/s.", "The object's motion is translational (linear), not rotating.", "Only positive mass and velocity are accepted." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "knitting-needle-converter", "name": "Knitting Needle Converter", "canonical_url": "https://boringtoolskit.com/knitting-needle-converter/", "category": "Converters", "description": "Knitting needle converter: US, mm and UK needle sizes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "kombucha-brew-calculator", "name": "Kombucha Brew Calculator", "canonical_url": "https://boringtoolskit.com/kombucha-brew-calculator/", "category": "Food & Cooking", "description": "Kombucha brew calculator: tea, sugar and starter for a batch.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "late-fee-calculator", "name": "Late Fee Calculator", "canonical_url": "https://boringtoolskit.com/late-fee-calculator/", "category": "Time & Work", "description": "Late fee calculator: penalty on an overdue invoice.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "law-of-cosines-calculator", "name": "Law of Cosines Calculator", "canonical_url": "https://boringtoolskit.com/law-of-cosines-calculator/", "category": "Everyday Calculators", "description": "Law of cosines calculator: third side from two sides and angle.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "lawn-seed-calculator", "name": "Lawn Seed Calculator", "canonical_url": "https://boringtoolskit.com/lawn-seed-calculator/", "category": "Construction & Measurement", "description": "Lawn seed calculator: pounds of seed needed for your lawn area.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "lean-body-mass-calculator", "name": "Lean Body Mass Calculator", "canonical_url": "https://boringtoolskit.com/lean-body-mass-calculator/", "category": "Health", "description": "Lean body mass calculator: LBM from weight and height (Boer).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "lease-vs-buy-calculator", "name": "Lease vs Buy Calculator", "canonical_url": "https://boringtoolskit.com/lease-vs-buy-calculator/", "category": "Vehicles", "description": "Lease vs buy calculator: compare total lease cost against loan ownership over the same term.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "led-savings-calculator", "name": "LED Savings Calculator", "canonical_url": "https://boringtoolskit.com/led-savings-calculator/", "category": "Energy & Electrical", "description": "Compare old and LED lighting energy cost, annual savings, and simple payback period.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/electricity-cost-calculator/", "/pay-raise-calculator/", "/battery-runtime-calculator/" ], "answer": "Compare old and LED lighting energy cost, annual savings, and simple payback period.", "formula": "Annual kWh = watts × bulb count × hours/day × 365 ÷ 1,000; savings = kWh reduction × rate; payback = upgrade cost ÷ annual savings.", "example": "", "assumptions": [ "Bulbs operate for the same number of hours at constant wattage.", "Light output and quality are assumed comparable but not verified.", "Replacement labor, lamp life, HVAC effects, rebates, and rate changes are excluded." ], "sources": [ { "organization": "ENERGY STAR", "title": "Learn about LED lighting", "url": "https://www.energystar.gov/products/lighting_fans/light_bulbs/learn_about_led_bulbs" }, { "organization": "EIA", "title": "Use of electricity", "url": "https://www.eia.gov/energyexplained/electricity/use-of-electricity.php" } ], "faqs": [ [ "How much can I save by switching to LED lighting?", "Savings depend on wattage, usage hours, and your electricity rate. This calculator compares the energy cost of old and LED lighting over the period you enter and reports the annual savings and simple payback period for the upgrade." ], [ "What is a simple payback period for LED bulbs?", "Payback period is the time it takes for accumulated energy savings to cover the upfront cost of the LED upgrade. This calculator divides the upgrade cost by the annual energy savings to show how many years the switch pays for itself." ], [ "Does the LED savings estimate include maintenance or replacement costs?", "The estimate focuses on energy-cost savings and the entered upgrade cost. It does not model bulb replacement frequency, dimming, or other maintenance differences, which may further favor LEDs because they typically last far longer." ] ] }, { "slug": "length-converter", "name": "Length Converter", "canonical_url": "https://boringtoolskit.com/length-converter/", "category": "Converters", "description": "Length converter: miles, kilometers, meters, feet, inches, yards.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "light-year-distance-calculator", "name": "Light Year Distance Calculator", "canonical_url": "https://boringtoolskit.com/light-year-distance-calculator/", "category": "Astronomy", "description": "Light year distance calculator: convert light years to kilometers, miles, and AU.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "lighting-ratio-calculator", "name": "Lighting Ratio Calculator", "canonical_url": "https://boringtoolskit.com/lighting-ratio-calculator/", "category": "Photo & Video", "description": "Lighting ratio calculator: convert main-to-fill stops to a lighting ratio and light falloff.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "limiting-reagent-calculator", "name": "Limiting Reagent Calculator", "canonical_url": "https://boringtoolskit.com/limiting-reagent-calculator/", "category": "Chemistry", "description": "Find the limiting reagent from two reactants and calculate product yield.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/stoichiometry-calculator/", "/percent-yield-calculator/", "/molar-mass-calculator/" ], "answer": "Find the limiting reagent from two reactants and calculate product yield.", "formula": "Moles of each reactant = mass ÷ molar mass. Equivalent = moles ÷ coefficient. The reactant with the smaller equivalent is the limiting reagent.", "example": "2 mol of reactant A (coefficient 1) and 3 mol of B (coefficient 2): A eq = 2, B eq = 1.5, so B is limiting.", "assumptions": [ "Both reactants' masses, molar masses, and coefficients are required.", "The comparison uses the mole-per-coefficient equivalent.", "The result identifies the limiting reagent, not the theoretical product mass." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "line-intersection-calculator", "name": "Line Intersection Calculator", "canonical_url": "https://boringtoolskit.com/line-intersection-calculator/", "category": "Everyday Calculators", "description": "Line intersection calculator: where two lines cross.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "linear-equation-solver", "name": "Linear Equation Solver", "canonical_url": "https://boringtoolskit.com/linear-equation-solver/", "category": "Everyday Calculators", "description": "Linear equation solver: ax + b = c.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "linear-interpolation-calculator", "name": "Linear Interpolation Calculator", "canonical_url": "https://boringtoolskit.com/linear-interpolation-calculator/", "category": "Everyday Calculators", "description": "Linear interpolation calculator: estimate y between two points.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "linear-regression-calculator", "name": "Linear Regression Calculator", "canonical_url": "https://boringtoolskit.com/linear-regression-calculator/", "category": "Statistics", "description": "Linear regression calculator: slope, intercept, and R-squared for a least-squares line through paired data.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "liters-to-ounces", "name": "Liters to Ounces Converter", "canonical_url": "https://boringtoolskit.com/liters-to-ounces/", "category": "Converters", "description": "Convert liters to US or imperial fluid ounces with common-value reference tables.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/baking-conversions/", "/unit-conv/", "/scientific-notation-converter/" ], "answer": "Convert liters to US or imperial fluid ounces with common-value reference tables.", "formula": "US fluid ounces = liters × 33.8140227. Imperial fluid ounces = liters × 35.1950797. 1 liter = 1,000 mL; 1 US cup = 236.6 mL.", "example": "2 liters = 2 × 33.814 = 67.6 US fluid ounces ≈ 70.4 imperial fluid ounces.", "assumptions": [ "The liter value is a volume measurement.", "Standard US and imperial conversion factors are used.", "The user selects the matching ounce system." ], "sources": [ { "organization": "Wikipedia", "title": "Litre", "url": "https://en.wikipedia.org/wiki/Litre" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How many ounces are in a liter?", "33.814 US fluid ounces or 35.195 imperial fluid ounces — depending on the system." ], [ "What's the difference between US and imperial ounces?", "The US fluid ounce is 29.573 mL; the imperial is 28.413 mL. They come from different gallon definitions." ], [ "How do I convert 2 liters?", "2 × 33.814 = 67.6 US fl oz; 2 × 35.195 = 70.4 imp fl oz." ], [ "Is a fluid ounce the same as a weight ounce?", "No — fluid ounces measure volume; weight ounces measure mass. For water they're nearly equal, but not for other liquids." ], [ "Why do recipes from the UK differ?", "UK recipes historically use imperial measures. A 500 mL UK recipe differs slightly from a US one using the same nominal amount." ], [ "How many liters is a gallon?", "A US gallon is 3.785 L; an imperial gallon is 4.546 L." ], [ "How many mL in a liter?", "Exactly 1,000 mL." ], [ "Is a liter more than a quart?", "Yes — a quart is 32 ounces; a liter is about 33.8 ounces." ], [ "Do US and imperial ounces differ?", "Yes — US fluid ounces are slightly larger than imperial ones." ] ] }, { "slug": "loan-comparison-calculator", "name": "Loan Comparison Calculator", "canonical_url": "https://boringtoolskit.com/loan-comparison-calculator/", "category": "Finance & Investing", "description": "Compare monthly payment, total interest, and total cost for two fixed-rate loans.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/auto-loan-calculator/", "/mortgage-payment-calculator/", "/loan-to-value-calculator/" ], "answer": "Compare monthly payment, total interest, and total cost for two fixed-rate loans.", "formula": "Each loan's monthly payment = principal × [r × (1+r)^n] ÷ [(1+r)^n − 1], where r = annual rate ÷ 12 and n = term in months; total cost = monthly payment × n + fees. The calculator compares two loans by monthly payment, total cost, and interest.", "example": "A $20,000 loan at 6% for 5 years (60 months) pays about $387/month, while the same amount at 7% for 4 years pays about $479/month — the calculator compares the full total cost including fees.", "assumptions": [ "Both loans share the same principal amount.", "Each loan is a fixed-rate amortizing loan.", "Fees are added to the total cost for comparison." ], "sources": [ { "organization": "Investopedia", "title": "Loan Comparison", "url": "https://www.investopedia.com/terms/l/loan-comparison.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I compare two loans?", "Compare the total cost (all payments + fees), not just the monthly payment. A shorter term or lower fees can beat a lower rate on total cost." ], [ "How is a loan payment calculated?", "M = P × [r(1+r)^n] ÷ [(1+r)^n − 1], where r is the monthly rate and n the number of payments." ], [ "Which is more important, rate or term?", "Both. A lower rate cuts cost, but a shorter term cuts interest dramatically even at a higher rate. Compare the combined effect." ], [ "Do fees change the comparison?", "Yes — origination fees and closing costs are part of the true cost. A lower-rate loan with high fees can be more expensive overall." ], [ "Should I pick the lower payment?", "Not automatically. A lower payment often means a longer term, which increases total interest. Compare total cost." ], [ "What is total interest?", "The sum of all interest you'd pay over the loan's life — the real cost of borrowing. It's often more than the loan itself for long auto loans." ], [ "Is a fixed or variable rate better?", "It depends on your risk tolerance and horizon. Fixed gives predictable payments; variable can start lower but rise. Compare total cost under both scenarios." ] ] }, { "slug": "loan-to-value-calculator", "name": "Loan-to-Value Calculator", "canonical_url": "https://boringtoolskit.com/loan-to-value-calculator/", "category": "Finance & Investing", "description": "Calculate your loan-to-value (LTV) ratio. Enter loan amount and property value to see equity position and PMI risk.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/debt-service-coverage-ratio-calculator/", "/down-payment-calculator/", "/mortgage-payment-calculator/" ], "answer": "Calculate your loan-to-value (LTV) ratio. Enter loan amount and property value to see equity position and PMI risk.", "formula": "Loan-to-value (LTV) = loan amount ÷ property value × 100. It expresses how much of a property is financed relative to its value; the remainder is your equity.", "example": "A $240,000 loan on a $300,000 property has an LTV of $240,000 ÷ $300,000 = 80%.", "assumptions": [ "LTV is based on loan amount and current property value (or appraisal).", "The calculator uses the values you enter — update them as value or balance changes.", "Values below 0 are rejected; a value of 0 returns no result." ], "sources": [ { "organization": "Investopedia", "title": "Loan-to-Value Ratio", "url": "https://www.investopedia.com/terms/l/loan-to-value-ratio.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What LTV do I need to avoid PMI?", "Most conventional loans require ≤80% LTV to avoid private mortgage insurance. Above 80% you typically pay PMI." ], [ "How is LTV calculated?", "LTV = loan amount ÷ property value × 100." ], [ "What is a good LTV?", "Lower is safer. Most lenders want a max of 80% for the best rates; 90–95% is common for first-time buyers but adds PMI." ], [ "Does LTV change over time?", "Yes. As you pay down the loan or if the property appreciates, your LTV falls. It can also rise if the market drops." ], [ "Why do lenders care about LTV?", "It measures their risk. A lower LTV means more equity cushion, so the loan is safer and usually gets a better rate." ], [ "Is LTV based on appraised or purchase value?", "Lenders use the appraised value, which can differ from the purchase price. Use the number your lender relies on." ], [ "What is equity in LTV?", "Equity is the portion of the property you own: value minus the loan balance. At 80% LTV you own 20% equity." ] ] }, { "slug": "local-income-tax-calculator", "name": "Local Income Tax Calculator", "canonical_url": "https://boringtoolskit.com/local-income-tax-calculator/", "category": "Finance & Investing", "description": "Local income tax calculator: which states levy county or city income taxes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "log-calculator", "name": "Logarithm Calculator", "canonical_url": "https://boringtoolskit.com/log-calculator/", "category": "Everyday Calculators", "description": "Calculate the logarithm of a number in any base, or natural log.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/exponent-calculator/", "/scientific-notation-converter/", "/fractions-calculator/" ], "answer": "Calculate the logarithm of a number in any base, or natural log.", "formula": "logₐ(x) = y means a^y = x. The tool computes ln(x) (natural log, base e), log₁₀(x) (common log), and log₂(x) (binary log). Input must be positive.", "example": "log₁₀(1000) = 3 because 10³ = 1000. log₂(8) = 3 because 2³ = 8. ln(e) = 1.", "assumptions": [ "The input is a positive real number.", "Standard definitions of ln, log₁₀, and log₂ are used.", "Results are rounded to six decimal places." ], "sources": [ { "organization": "Math Is Fun", "title": "Logarithms", "url": "https://www.mathsisfun.com/algebra/logarithms.html" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a logarithm?", "The inverse of exponentiation. logₐ(x) asks: to what power must I raise the base a to get x? For example, log₁₀(1000) = 3." ], [ "What is the natural logarithm (ln)?", "A logarithm with base e (≈ 2.718). It's the default in calculus, growth models, and finance: ln(e) = 1." ], [ "What is log₂ used for?", "Binary logarithms are everywhere in computing — information bits, binary search, and algorithm complexity (log₂ of 8 is 3, meaning 2³ = 8)." ], [ "Why must the input be positive?", "Because a power of a positive base is always positive — you can never reach zero or a negative number by raising a positive base to a real exponent." ], [ "What does a negative logarithm mean?", "The number is between 0 and 1. For example, log₁₀(0.01) = −2 because 10⁻² = 0.01." ], [ "How do I convert between bases?", "Use the change-of-base rule: logₐ(x) = log_b(x) ÷ log_b(a). For example, log₂(8) = log₁₀(8) ÷ log₁₀(2) ≈ 3." ], [ "Where do logarithms appear in real life?", "pH, decibels, earthquake magnitude, sound levels, compound growth, doubling times, and computer science complexity." ], [ "What is the difference between log and ln?", "Log is base 10; ln is base e (natural)." ], [ "What is the log of a negative number?", "Undefined in real numbers — logs require positive arguments." ] ] }, { "slug": "logarithm-calculator", "name": "Logarithm Calculator", "canonical_url": "https://boringtoolskit.com/logarithm-calculator/", "category": "Generators", "description": "Logarithm calculator: log base 10, 2, e, or any custom base of a number, with the inverse check.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "long-division-calculator", "name": "Long Division Calculator", "canonical_url": "https://boringtoolskit.com/long-division-calculator/", "category": "School & Education", "description": "Long division calculator: quotient and remainder with the steps shown.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "loot-box-ev-calculator", "name": "Loot Box EV Calculator", "canonical_url": "https://boringtoolskit.com/loot-box-ev-calculator/", "category": "Gaming", "description": "Loot box expected value calculator: what a box is really worth from drop odds and item values.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "loot-drop-probability-calculator", "name": "Loot Drop Probability Calculator", "canonical_url": "https://boringtoolskit.com/loot-drop-probability-calculator/", "category": "Gaming", "description": "Loot drop probability calculator: chance of at least one drop after N attempts at a given drop rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "lottery-odds-calculator", "name": "Lottery Odds Calculator", "canonical_url": "https://boringtoolskit.com/lottery-odds-calculator/", "category": "Gaming", "description": "Lottery odds calculator: jackpot odds for any 5+1 or 6-number game.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "love-calculator", "name": "Love Compatibility Calculator", "canonical_url": "https://boringtoolskit.com/love-calculator/", "category": "Social Media", "description": "Love compatibility calculator: a fun, deterministic name-based score. Entertainment only.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "luggage-volume-calculator", "name": "Luggage Volume Calculator", "canonical_url": "https://boringtoolskit.com/luggage-volume-calculator/", "category": "Travel", "description": "Luggage volume calculator: bag capacity in liters from dimensions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "lumber-calculator", "name": "Lumber Calculator", "canonical_url": "https://boringtoolskit.com/lumber-calculator/", "category": "Construction & Measurement", "description": "Lumber calculator: board feet and total cost from nominal dimensions and length.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "lumens-calculator", "name": "Lumens Calculator", "canonical_url": "https://boringtoolskit.com/lumens-calculator/", "category": "Energy & Electrical", "description": "Lumens calculator: light output needed for a room.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "luminance-calculator", "name": "Luminance Brightness Calculator", "canonical_url": "https://boringtoolskit.com/luminance-calculator/", "category": "Colors & Design", "description": "Luminance calculator: relative luminance of a hex color and its perceived brightness.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "lump-sum-vs-dca-calculator", "name": "Lump Sum Vs Dca Calculator", "canonical_url": "https://boringtoolskit.com/lump-sum-vs-dca-calculator/", "category": "Finance & Investing", "description": "Compare investing a lump sum now versus dollar-cost averaging the same money monthly. See which strategy wins at your time horizon and return.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "macro-magnification-calculator", "name": "Macro Magnification Calculator", "canonical_url": "https://boringtoolskit.com/macro-magnification-calculator/", "category": "Photo & Video", "description": "Macro magnification calculator: reproduction ratio from extension tube and lens focal length.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "macro-planning-calculator", "name": "Macro Planning Calculator", "canonical_url": "https://boringtoolskit.com/macro-planning-calculator/", "category": "Health", "description": "Allocate a user-selected adult calorie total across configurable protein, fat, and carbohydrate assumptions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/calorie-calc/", "/bmr-tdee-calculator/", "/body-fat-calculator/" ], "answer": "Allocate a user-selected adult calorie total across configurable protein, fat, and carbohydrate assumptions.", "formula": "Protein grams = body weight (kg) × protein target (g/kg). Fat grams = daily calories × fat % ÷ 9. Carbohydrate grams = (calories − protein×4 − fat×9) ÷ 4.", "example": "2,000 calories at 80 kg with 1.6 g/kg protein and 30% fat: protein 128 g, fat ≈ 67 g, carbs ≈ 222 g.", "assumptions": [ "The user is an adult (18+ confirmation).", "Protein and carbs are 4 cal/g; fat is 9 cal/g.", "Targets are entered within healthy planning ranges." ], "sources": [ { "organization": "Wikipedia", "title": "Macronutrient", "url": "https://en.wikipedia.org/wiki/Macronutrient" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate macros?", "Protein = weight × g/kg; fat = calories × % ÷ 9; carbs = (calories − protein×4 − fat×9) ÷ 4." ], [ "How much protein do I need?", "1.6–2.2 g/kg for most active adults; more for intense training, less for maintenance." ], [ "Why is fat 9 calories per gram?", "Fat is more energy-dense than protein and carbs (4 cal/g each) — that's the standard conversion." ], [ "Is this medical advice?", "No — it's planning math. Needs vary with health conditions; consult a professional." ], [ "How do I split macros across meals?", "Divide the daily grams by the number of meals, or use percentages per meal." ], [ "What if I'm not losing weight?", "Adjust calories first (typically −10–20%), keep protein high to preserve muscle." ], [ "Do macros work for any diet?", "Yes — keto, balanced, and high-protein diets all set these three targets differently." ], [ "How do I calculate my macros?", "Set calories, protein per kg, fat percent, then carbs fill the rest." ], [ "What percent of calories from fat?", "20–35% is the common healthy range." ], [ "Do macros matter more than calories?", "Calories decide weight change; macros shape composition and performance." ] ] }, { "slug": "macro-split-calculator", "name": "Macro Split Calculator", "canonical_url": "https://boringtoolskit.com/macro-split-calculator/", "category": "Health", "description": "Macro split calculator: carbs from calories, protein, and fat targets.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "maintenance-calories-calculator", "name": "Maintenance Calories Calculator", "canonical_url": "https://boringtoolskit.com/maintenance-calories-calculator/", "category": "Health", "description": "Maintenance calories calculator: calories to hold your weight (Mifflin-St Jeor).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "marathon-predictor", "name": "Marathon Pace Predictor", "canonical_url": "https://boringtoolskit.com/marathon-predictor/", "category": "Sports", "description": "Marathon pace predictor: race-time predictions from a recent race using the Riegel formula.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "margin-of-error-calculator", "name": "Margin of Error Calculator", "canonical_url": "https://boringtoolskit.com/margin-of-error-calculator/", "category": "Statistics", "description": "Margin of error calculator: sampling error for a survey at a chosen confidence level.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "markdown-table-generator", "name": "Markdown Table Generator", "canonical_url": "https://boringtoolskit.com/markdown-table-generator/", "category": "Everyday Calculators", "description": "Paste rows and columns of text and get a clean GitHub-flavored markdown (GFM) pipe table you can drop into READMEs and docs.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/csv-to-json/", "/text-case/", "/word-counter/" ], "answer": "Paste rows and columns of text and get a clean GitHub-flavored markdown (GFM) pipe table you can drop into READMEs and docs.", "formula": "Parses delimited rows (CSV, tabs, pipes) and renders a GitHub-flavored Markdown table: a header row, a separator row, and body rows with pipe-aligned columns.", "example": "Pasting 'Name,Role,City\\nAlice,Engineer,NYC' generates a 3-column markdown table.", "assumptions": [ "The first row is the header.", "Rows have consistent column counts.", "The target renderer supports GFM tables." ], "sources": [ { "organization": "Wikipedia", "title": "Markdown", "url": "https://en.wikipedia.org/wiki/Markdown" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I make a markdown table?", "Paste your data as CSV, tabs, or pipes and generate — the tool outputs the header, separator, and row markup." ], [ "What delimiters are supported?", "Commas, tabs, and pipes — matching spreadsheet exports and common data formats." ], [ "What happens to the first row?", "It becomes the table header." ], [ "How are pipes in cells handled?", "They're escaped so the table structure stays intact." ], [ "Does the alignment syntax matter?", "No — the :---: alignment markers are cosmetic in most renderers." ], [ "Can I paste from Excel/Sheets?", "Yes — copy the cells and paste; spreadsheet copies are tab-delimited." ], [ "Where do markdown tables work?", "GitHub, GitLab, Notion, and most static site generators render GFM tables." ] ] }, { "slug": "market-cap-calculator", "name": "Market Cap Calculator", "canonical_url": "https://boringtoolskit.com/market-cap-calculator/", "category": "Finance & Investing", "description": "Market cap calculator: company value from shares and price.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "market-value-calculator", "name": "Market Value Calculator", "canonical_url": "https://boringtoolskit.com/market-value-calculator/", "category": "Real Estate", "description": "Estimate a property's market value from comparable price per square foot and quality adjustments.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/price-per-square-foot/", "/property-area-calculator/", "/renovation-calculator/" ], "answer": "Estimate a property's market value from comparable price per square foot and quality adjustments.", "formula": "Base value = property area × price per square foot. Estimated market value = base value × (1 + (quality adjustment + condition adjustment) ÷ 100).", "example": "A 2,000 sq ft property at $200/sq ft with a +5% quality adjustment and 0% condition adjustment: base = $400,000, estimated market value = $400,000 × 1.05 = $420,000.", "assumptions": [ "Area and price-per-square-foot are entered by the user.", "Quality and condition adjustments are percentages applied to the base.", "The result is a rough estimate, not a formal appraisal." ], "sources": [ { "organization": "Investopedia", "title": "Market Value", "url": "https://www.investopedia.com/terms/m/marketvalue.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is market value?", "The price a property would likely sell for between a willing buyer and seller in the current market. It's an estimate of what a home is worth today." ], [ "How is the price-per-square-foot method used?", "Divide recent comparable sale prices by their areas to get a typical $/sq ft, multiply it by the property's area, then adjust for quality and condition." ], [ "Why adjust for quality and condition?", "Two homes of the same size can differ hugely in value — finishes, upgrades, and maintenance matter. Adjustments shift the base estimate to reflect those differences." ], [ "Is this an appraisal?", "No. An appraisal is a licensed professional's opinion based on full comparable analysis and inspection. This calculator is a quick planning estimate." ], [ "Why is price per square foot misleading sometimes?", "It averages out lot size, views, floor-plan efficiency, and location nuances. A high-end area's $/sq ft doesn't apply a few blocks away." ], [ "What should I compare against?", "Recent closed sales of similar properties in the same neighborhood — ideally within the last 3–6 months, with similar size, age, and condition." ], [ "Should I trust the adjusted number?", "Use it as a starting point, then validate with real comps or an appraisal before making an offer or listing price." ] ] }, { "slug": "marketplace-ad-break-even-calculator", "name": "Marketplace Advertising Break-Even Calculator", "canonical_url": "https://boringtoolskit.com/marketplace-ad-break-even-calculator/", "category": "Seller & Business", "description": "Calculate break-even ROAS and ACOS after product cost, marketplace fees, payment fees, fulfillment, shipping, returns allowance, and target profit.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/break-even-units-calculator/", "/price-increase-impact-calculator/", "/customer-lifetime-value-calculator/" ], "answer": "Calculate break-even ROAS and ACOS after product cost, marketplace fees, payment fees, fulfillment, shipping, returns allowance, and target profit.", "formula": "Break-even ROAS = 1 ÷ gross margin %. At break-even, ad spend = margin dollars from the sale. The tool also shows the max ad cost per sale.", "example": "At 30% gross margin, break-even ROAS = 1 ÷ 0.30 ≈ 3.33× — every $1 of ad spend must produce $3.33 of sales just to break even.", "assumptions": [ "Margin is constant across sales.", "Attribution of ad sales is accurate.", "All ad spend is variable (no fixed fees)." ], "sources": [ { "organization": "Wikipedia", "title": "Advertising", "url": "https://en.wikipedia.org/wiki/Advertising" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is break-even ROAS?", "The ROAS where ad spend exactly consumes the margin: 1 ÷ margin %. At 30% margin, that's 3.33×." ], [ "How do I calculate it?", "Break-even ROAS = 1 ÷ gross margin. For a $10 product with $3 margin (30%), you need $3.33 of sales per $1 of ads." ], [ "What's a good ROAS?", "Above your break-even — which depends on margin, not a universal number. High-margin products break even at lower ROAS." ], [ "Why is ROAS misleading?", "It measures revenue, not profit. A low-margin product can hit high ROAS and still lose money." ], [ "What if I'm below break-even?", "Cut ad spend, improve the listing conversion, raise prices, or focus on higher-margin products." ], [ "Does this include returns?", "No — returns reduce real margin. Subtract return rates from margin for accuracy." ], [ "How do I know which sales came from ads?", "Use platform attribution and test with campaigns — that's the hardest part of the math." ] ] }, { "slug": "matrix-calculator", "name": "Matrix Calculator", "canonical_url": "https://boringtoolskit.com/matrix-calculator/", "category": "Everyday Calculators", "description": "Add, subtract, or multiply 2x2 and 3x3 matrices.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/quadratic-formula-calculator/", "/general-scientific-calculator/", "/exponent-calculator/" ], "answer": "Add, subtract, or multiply 2x2 and 3x3 matrices.", "formula": "Addition/subtraction: C[i][j] = A[i][j] ± B[i][j] (same size). Multiplication (n×n): C[i][j] = Σₖ A[i][k] × B[k][j]. The tool handles square matrices of size 2–4.", "example": "Adding 2×2 matrices [[1,2],[3,4]] + [[5,6],[7,8]] = [[6,8],[10,12]]. Multiplying [[1,2],[3,4]] × [[2,0],[1,2]] = [[4,4],[10,8]].", "assumptions": [ "Matrices are square (n×n).", "Entries are real numbers.", "Multiplication uses standard row-by-column dot products." ], "sources": [ { "organization": "Wikipedia", "title": "Matrix (mathematics)", "url": "https://en.wikipedia.org/wiki/Matrix_(mathematics)" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a matrix?", "A rectangular grid of numbers with rows and columns, used in math, physics, graphics, and data science to organize and transform information." ], [ "How do I add matrices?", "Add corresponding entries: [[1,2],[3,4]] + [[5,6],[7,8]] = [[6,8],[10,12]]. Both must be the same size." ], [ "How do I multiply matrices?", "For each result cell, sum the products of row i of A with column j of B: C[i][j] = Σ A[i][k]×B[k][j]." ], [ "Is matrix multiplication commutative?", "No — AB usually differs from BA. Order matters, unlike ordinary number multiplication." ], [ "What sizes does the tool support?", "Square matrices of size 2, 3, or 4. Larger or rectangular matrices need a general-purpose tool." ], [ "What are matrices used for?", "Solving systems of equations, computer graphics transformations, Markov processes, and representing data in machine learning." ], [ "What is an identity matrix?", "A square matrix with 1s on the diagonal and 0s elsewhere — the multiplicative identity: A × I = A." ] ] }, { "slug": "matrix-determinant-calculator", "name": "Matrix Determinant Calculator", "canonical_url": "https://boringtoolskit.com/matrix-determinant-calculator/", "category": "Everyday Calculators", "description": "3x3 matrix determinant calculator.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "matrix-transpose-calculator", "name": "Matrix Transpose Calculator", "canonical_url": "https://boringtoolskit.com/matrix-transpose-calculator/", "category": "Everyday Calculators", "description": "Matrix transpose calculator: flip a 2x3 matrix.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "maximum-allowable-offer-calculator", "name": "Maximum Allowable Offer Calculator", "canonical_url": "https://boringtoolskit.com/maximum-allowable-offer-calculator/", "category": "Finance & Investing", "description": "Calculate the maximum allowable offer (MAO) for a flip using the 70% rule. Enter ARV, rehab, and holding costs.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/after-repair-value-calculator/", "/fix-and-flip-profit-calculator/", "/cap-rate-calculator/" ], "answer": "Calculate the maximum allowable offer (MAO) for a flip using the 70% rule. Enter ARV, rehab, and holding costs.", "formula": "Maximum allowable offer = after-repair value × 70% − rehabilitation cost (the 70% rule). The tool also computes the profit-based offer: ARV − rehab − holding costs − desired profit.", "example": "With an ARV of $300,000 and $40,000 in rehab, the 70% rule offer = $300,000 × 0.70 − $40,000 = $170,000.", "assumptions": [ "The 70% rule and profit-based offer are both computed from the same inputs.", "Holding costs and desired profit are user-entered for the profit-based offer.", "Actual values depend on accurate ARV and rehab estimates." ], "sources": [ { "organization": "Investopedia", "title": "Maximum Allowable Offer", "url": "https://www.investopedia.com/terms/m/maximum-allowable-offer.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is the 70% rule in real estate?", "A fix-and-flip guide: the maximum offer should be about 70% of the after-repair value minus the repair cost. It preserves a profit margin." ], [ "How do I calculate maximum allowable offer?", "MAO = (0.70 × ARV) − repair cost. A more precise version also subtracts holding costs and your target profit." ], [ "Why the 70% number?", "It's a safety margin that accounts for real-world friction — selling fees, holding time, and the fact that rehabs often cost more than planned." ], [ "Can MAO be higher than 70%?", "Yes, in competitive markets investors sometimes use 75-80%. It means a thinner margin and higher risk." ], [ "Does MAO include closing costs?", "The basic 70% rule doesn't. The profit-based variant should include buyer closing costs and holding costs for accuracy." ], [ "What if my ARV estimate is wrong?", "The whole deal depends on ARV. Use conservative, comp-supported ARV before trusting the MAO — overestimating ARV produces an offer too high to profit." ], [ "Is the 70% rule a guarantee of profit?", "No. It's a screening tool that reduces risk. Real outcomes depend on accurate rehab and resale estimates." ] ] }, { "slug": "meal-prep-calculator", "name": "Meal Prep Calculator", "canonical_url": "https://boringtoolskit.com/meal-prep-calculator/", "category": "Food & Cooking", "description": "Meal prep calculator: batch quantity for meal prep.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "mean-arterial-pressure-calculator", "name": "Mean Arterial Pressure Calculator", "canonical_url": "https://boringtoolskit.com/mean-arterial-pressure-calculator/", "category": "Health", "description": "Mean arterial pressure calculator: MAP from systolic and diastolic.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "mean-median-mode-calculator", "name": "Mean Median Mode Calculator", "canonical_url": "https://boringtoolskit.com/mean-median-mode-calculator/", "category": "Everyday Calculators", "description": "Calculate mean, median, mode, range, sum, and count for any list of numbers.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/statistics-calculator/", "/standard-deviation-calculator/", "/weighted-average-calculator/" ], "answer": "Calculate mean, median, mode, range, sum, and count for any list of numbers.", "formula": "Mean = sum ÷ count. Median = the middle value of the sorted list (or the average of the two middles for even counts). Mode = the most frequent value(s).", "example": "For [1, 2, 2, 3, 4]: mean = 2.4, median = 2, mode = 2.", "assumptions": [ "At least one number is entered.", "Values are numeric.", "Standard definitions apply for ties." ], "sources": [ { "organization": "Wikipedia", "title": "Average", "url": "https://en.wikipedia.org/wiki/Average" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is the mean?", "The average — sum ÷ count: (1+2+2+3+4) ÷ 5 = 2.4." ], [ "What is the median?", "The middle of the sorted list — 2 in [1,2,2,3,4]." ], [ "What is the mode?", "The most frequent value — 2 appears twice in the example." ], [ "Why are they different?", "They measure center differently; outliers inflate the mean but not the median." ], [ "Which should I use?", "Median for skewed data (salaries, prices); mean for symmetric data; mode for common values." ], [ "Can there be two modes?", "Yes — bimodal data has two most-frequent values." ], [ "How do I compute the median for an even count?", "Average the two middle values." ] ] }, { "slug": "meat-cooking-time-calculator", "name": "Meat Cooking Time Calculator", "canonical_url": "https://boringtoolskit.com/meat-cooking-time-calculator/", "category": "Food & Cooking", "description": "Meat cooking time calculator: roast time by weight and type.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "meat-doneness-temperature-calculator", "name": "Meat Doneness Temperature Calculator", "canonical_url": "https://boringtoolskit.com/meat-doneness-temperature-calculator/", "category": "Food & Cooking", "description": "Meat doneness temperature guide: target internal temperatures for beef, pork, chicken, and lamb.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "medicine-dosage-calculator", "name": "Medicine Dosage Calculator", "canonical_url": "https://boringtoolskit.com/medicine-dosage-calculator/", "category": "Health", "description": "Medicine dosage calculator: dose from body weight and mg/kg dosing instructions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "meeting-cost-calculator", "name": "Meeting Cost Calculator", "canonical_url": "https://boringtoolskit.com/meeting-cost-calculator/", "category": "Time & Work", "description": "Estimate direct meeting labor cost, cost per minute, participant-hours, and annual recurring cost from editable compensation assumptions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/freelance-hourly-rate-calculator/", "/salary-hourly-converter/", "/paycheck-calc/", "/research/meeting-cost-scenarios/" ], "answer": "Recurring meeting annual cost: estimate one meeting, then annualize a weekly recurrence from participants, duration, and loaded hourly cost.", "formula": "Cost per meeting = (blended hourly cost × uplift) × duration hours. Annual cost = per-meeting cost × meetings per week × working weeks per year.", "example": "6 people at an average $50/hour with a 30% overhead uplift, in a 1-hour meeting: $390 per meeting — over $20,000 a year if held weekly.", "assumptions": [ "The uplift reflects benefits and overhead.", "All attendees' time is fully occupied by the meeting.", "Recurrence is consistent across the year." ], "sources": [ { "organization": "Wikipedia", "title": "Opportunity cost", "url": "https://en.wikipedia.org/wiki/Opportunity_cost" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate meeting cost?", "Attendees' hourly cost × uplift × hours: 6 × $50 × 1.3 = $390 for an hour." ], [ "What is the uplift for?", "It covers benefits, payroll taxes, and overhead — the real cost of an employee hour is 1.3–2× the salary." ], [ "How do I estimate annual cost?", "Per-meeting cost × meetings per week × working weeks (52): $390 × 52 ≈ $20,000+." ], [ "Does this include prep time?", "No — prep and follow-up add 30–50% more in practice." ], [ "Is this just for executives?", "No — a meeting of six mid-level staff at $40/hr still costs $1,600/week or $80k+/year." ], [ "How do I decide if a meeting is worth it?", "Compare the cost to the value of the decision it produces — and ask if email or async updates could do it." ], [ "What makes meetings cheaper?", "Fewer attendees, shorter duration, async alternatives, and standing agendas." ], [ "What should the hourly rate include?", "Loaded cost — salary plus benefits and overhead, typically 125–140% of wage." ], [ "How much do weekly meetings cost?", "A 1-hour 6-person meeting at loaded rates runs about $20,000 per year." ], [ "What is the cheapest fix?", "Cut attendees, shorten the meeting, or move updates to async." ] ] }, { "slug": "menstrual-cycle-calculator", "name": "Menstrual Cycle Calculator", "canonical_url": "https://boringtoolskit.com/menstrual-cycle-calculator/", "category": "Health", "description": "Menstrual cycle calculator: next period and estimated fertile window (private, no tracking stored).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "mercari-fee-calculator", "name": "Mercari Fee Calculator", "canonical_url": "https://boringtoolskit.com/mercari-fee-calculator/", "category": "Seller & Business", "description": "Mercari fee calculator: the flat 10% selling fee and your net.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "mercury-retrograde-calculator", "name": "Mercury Retrograde Calculator", "canonical_url": "https://boringtoolskit.com/mercury-retrograde-calculator/", "category": "Astrology", "description": "Mercury retrograde calculator: check if a date falls in a retrograde window, 2024-2030.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "meta-tags", "name": "Meta Tag Generator", "canonical_url": "https://boringtoolskit.com/meta-tags/", "category": "Text & Developer Tools", "description": "Generate meta tags and social preview strings.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/keyword-density-calculator/", "/readability/", "/sitemap-validate/" ], "answer": "Generate meta tags and social preview strings.", "formula": "Generates an HTML head block from inputs: title, meta description, author, language, robots directive, canonical URL, and Open Graph tags (og:title, og:description, og:image, og:type) for social sharing.", "example": "A page titled 'Free BMI Calculator' with a 150-character description generates the full , <meta name=\"description\">, and OG tags to paste into the page head.", "assumptions": [ "The user supplies accurate page details.", "OG image URLs are absolute and accessible.", "Tags are placed in the HTML <head>." ], "sources": [ { "organization": "Wikipedia", "title": "Meta element", "url": "https://en.wikipedia.org/wiki/Meta_element" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What are meta tags?", "HTML tags in the page head that describe the page: title, description, robots directives, canonical URL, and Open Graph/social metadata." ], [ "What length should a title be?", "About 60 characters to avoid truncation in search results. Keep the primary keyword near the front." ], [ "What length should a description be?", "About 150–160 characters — long enough to summarize, short enough to display fully." ], [ "What is Open Graph?", "A protocol (og: tags) that controls how links appear when shared on Facebook, LinkedIn, and other platforms." ], [ "What is a canonical tag?", "The preferred URL for a page — it tells search engines which version to index when duplicates exist." ], [ "Do meta tags guarantee rankings?", "No — they inform the search engines and shape click-through, but ranking depends on content, relevance, and authority." ], [ "Why does Google ignore my title?", "Google rewrites titles and descriptions when it decides the page content better represents the query — keep tags accurate and relevant." ], [ "How long should a title be?", "50–60 characters before truncation in search results." ], [ "How long should a description be?", "150–160 characters — the click-driving summary in search results." ], [ "What are Open Graph tags?", "og:title, og:description, and og:image — controlling social share previews." ] ] }, { "slug": "metabolic-age-calculator", "name": "Metabolic Age Calculator", "canonical_url": "https://boringtoolskit.com/metabolic-age-calculator/", "category": "Health", "description": "Metabolic age calculator: how your BMR compares to your age group.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "metric-prefix-converter", "name": "Metric Prefix Converter", "canonical_url": "https://boringtoolskit.com/metric-prefix-converter/", "category": "Converters", "description": "Metric prefix converter: kilo, mega, giga, tera and friends.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "metronome-bpm-calculator", "name": "Metronome BPM Calculator", "canonical_url": "https://boringtoolskit.com/metronome-bpm-calculator/", "category": "Music & Audio", "description": "Convert traditional tempo markings to BPM and see milliseconds per beat.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/bpm-to-ms-calculator/", "/audio-time-stretch-calculator/", "/scale-finder-calculator/" ], "answer": "Convert traditional tempo markings to BPM and see milliseconds per beat.", "formula": "Tempo is set as beats per minute (BPM); the metronome converts BPM to a click interval between quarter-note beats (60,000 ÷ BPM ms) and supports standard tempo markings (larghissimo ~25 to prestissimo ~208).", "example": "A 120 BPM setting clicks every 500 ms. A 'Moderato' marking corresponds to an approximate 92–114 BPM range.", "assumptions": [ "BPM is the user's input; tempo markings are approximate ranges.", "The audible click uses the Web Audio API and starts on explicit user action.", "The default time signature is 4/4 unless changed." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "midpoint-calculator", "name": "Midpoint Calculator", "canonical_url": "https://boringtoolskit.com/midpoint-calculator/", "category": "School & Education", "description": "Midpoint calculator: the midpoint of a line segment between two points.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "mileage-log-calculator", "name": "Mileage Log Calculator", "canonical_url": "https://boringtoolskit.com/mileage-log-calculator/", "category": "Time & Work", "description": "Mileage log calculator: monthly and yearly mileage deductions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "mileage-reimbursement-calculator", "name": "Mileage Reimbursement Calculator", "canonical_url": "https://boringtoolskit.com/mileage-reimbursement-calculator/", "category": "Time & Work", "description": "Mileage reimbursement calculator: business miles at the IRS standard rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "modulo-calculator", "name": "Modulo Calculator", "canonical_url": "https://boringtoolskit.com/modulo-calculator/", "category": "Everyday Calculators", "description": "Modulo calculator: remainder of a divided by b.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "molar-mass-calculator", "name": "Molar Mass Calculator", "canonical_url": "https://boringtoolskit.com/molar-mass-calculator/", "category": "Chemistry", "description": "Calculate the molar mass of a compound from its chemical formula.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/empirical-formula-calculator/", "/average-atomic-mass-calculator/", "/stoichiometry-calculator/" ], "answer": "Calculate the molar mass of a compound from its chemical formula.", "formula": "Molar mass = Σ (atomic mass of each element × its count in the formula).", "example": "H₂O: 2 × 1.008 + 15.999 = 18.015 g/mol. CO₂: 12.011 + 2 × 15.999 = 44.009 g/mol.", "assumptions": [ "Atomic masses use the standard values embedded in the tool.", "The formula is parsed element-by-element; unsupported elements are flagged.", "The result is the molar mass of one formula unit." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "molarity-calculator", "name": "Molarity Calculator", "canonical_url": "https://boringtoolskit.com/molarity-calculator/", "category": "Chemistry", "description": "Calculate molarity from moles and volume, with solution prep details.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/molarity-from-mass-calculator/", "/dilution-calculator/", "/percent-solution-calculator/" ], "answer": "Calculate molarity from moles and volume, with solution prep details.", "formula": "Molarity (M) = moles of solute ÷ volume of solution in liters. Concentration = molar mass × M (g/L).", "example": "0.5 mol of solute dissolved in 2 L: M = 0.5 ÷ 2 = 0.25 mol/L. With a molar mass of 58 g/mol, concentration = 58 × 0.25 = 14.5 g/L.", "assumptions": [ "Moles and volume are the user's inputs; volume must be positive.", "If molar mass is given, the solution concentration is also reported in g/L.", "The solution volume is in liters, not milliliters." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "molarity-from-mass-calculator", "name": "Molarity from Mass Calculator", "canonical_url": "https://boringtoolskit.com/molarity-from-mass-calculator/", "category": "Chemistry", "description": "Convert grams of solute to molarity using molar mass and volume.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/molarity-calculator/", "/molar-mass-calculator/", "/percent-solution-calculator/" ], "answer": "Convert grams of solute to molarity using molar mass and volume.", "formula": "Moles = solute mass ÷ molar mass. Molarity = moles ÷ (volume in mL ÷ 1000). Concentration = mass ÷ (volume ÷ 1000) g/L.", "example": "10 g of a substance with molar mass 58 g/mol in 500 mL: moles = 10 ÷ 58 = 0.172 mol, M = 0.172 ÷ 0.5 = 0.345 mol/L.", "assumptions": [ "Solute mass, molar mass, and solution volume (in mL) are required.", "Molar mass and volume must be positive.", "Volume is converted from mL to L internally." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "mole-calculator", "name": "Mole Calculator", "canonical_url": "https://boringtoolskit.com/mole-calculator/", "category": "Chemistry", "description": "Mole calculator: moles from mass and molar mass (chemistry).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "momentum-calculator", "name": "Momentum Calculator", "canonical_url": "https://boringtoolskit.com/momentum-calculator/", "category": "Physics", "description": "Calculate linear momentum from mass and velocity (p = mv).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/force-calculator/", "/kinetic-energy-calculator/", "/angular-momentum-calculator/" ], "answer": "Calculate linear momentum from mass and velocity (p = mv).", "formula": "Momentum (p) = mass × velocity. Units: kg · m/s.", "example": "A 0.9 kg ball moving at 10 m/s: p = 0.9 × 10 = 9 kg·m/s.", "assumptions": [ "Mass is in kilograms and velocity in m/s.", "Momentum is a vector along the direction of motion.", "Positive values are required for both inputs." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "monitor-height-calculator", "name": "Monitor Height Calculator", "canonical_url": "https://boringtoolskit.com/monitor-height-calculator/", "category": "Time & Work", "description": "Monitor height calculator: screen position from eye level.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "moon-phase-calculator", "name": "Moon Phase Calculator", "canonical_url": "https://boringtoolskit.com/moon-phase-calculator/", "category": "Astronomy", "description": "Moon phase calculator: current moon phase from the synodic cycle.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "morse-code-converter", "name": "Morse Code Converter", "canonical_url": "https://boringtoolskit.com/morse-code-converter/", "category": "Text & Developer Tools", "description": "Morse code converter: text to Morse and back.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "mortgage-afford", "name": "Mortgage Affordability Calculator", "canonical_url": "https://boringtoolskit.com/mortgage-afford/", "category": "Finance & Investing", "description": "Find an affordable home price from income, debts, down payment, rate, taxes, insurance, HOA, and your DTI cap.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/mortgage-payment-calculator/", "/down-payment-calculator/", "/loan-comparison-calculator/" ], "answer": "Find an affordable home price from income, debts, down payment, rate, taxes, insurance, HOA, and your DTI cap.", "formula": "Affordable mortgage is solved by setting the monthly housing payment (principal + interest + property tax + insurance + HOA) against your gross monthly income and existing debts, using a target debt-to-income ratio (commonly 28% front-end, 36% back-end).", "example": "A $90,000 gross annual income ($7,500/month), no debts, with a 6.5% rate, 30-year term, 20% down, and $350/month taxes+insurance, supports roughly a $400,000 purchase at a 36% back-end DTI.", "assumptions": [ "The target DTI (28% front-end / 36% back-end) is a standard guideline, not a guarantee.", "Property tax, insurance, and HOA are included in the monthly payment.", "The result is an estimate, not a pre-approval — a lender sets the final number." ], "sources": [ { "organization": "Investopedia", "title": "Mortgage Affordability", "url": "https://www.investopedia.com/terms/m/mortgage.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How much house can I afford?", "A common guideline keeps your total housing payment at or under 28% of gross income, and all debts under 36%. The calculator applies this to your income." ], [ "What is the 28/36 rule?", "The 28% front-end (housing only) and 36% back-end (all debt) DTI benchmarks many lenders use as a cap." ], [ "Does the payment include taxes and insurance?", "Yes — a true housing payment includes principal, interest, property tax, and insurance (plus HOA if applicable). The calculator uses the full figure." ], [ "What counts toward DTI?", "Gross monthly income in the denominator; the housing payment and all other minimum debt payments in the numerator." ], [ "Can I afford more than DTI says?", "Often, but a lender may not approve it, and living at the DTI ceiling leaves little room for savings or unexpected costs. Aim for comfort, not the max." ], [ "Should I get pre-approved?", "Yes — a real pre-approval from a lender gives the exact qualifying number and rate, far more accurate than an estimate." ], [ "How does the down payment affect it?", "A bigger down payment reduces the loan amount and monthly payment, and can also avoid private mortgage insurance (below 20% typically adds PMI)." ] ] }, { "slug": "mortgage-escrow-calculator", "name": "Mortgage Escrow Calculator", "canonical_url": "https://boringtoolskit.com/mortgage-escrow-calculator/", "category": "Finance & Investing", "description": "Mortgage escrow calculator: monthly escrow payment from annual property tax and insurance.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "mortgage-overpayment-calculator", "name": "Mortgage Overpayment Calculator", "canonical_url": "https://boringtoolskit.com/mortgage-overpayment-calculator/", "category": "Finance & Investing", "description": "See how extra monthly payments or a one-time lump sum cut years off a mortgage and save interest. Enter loan, rate, term, and overpayments for a private estimate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/mortgage-payment-calculator/", "/amortization-calculator/", "/mortgage-refinance-break-even/" ], "answer": "See how extra monthly payments or a one-time lump sum cut years off a mortgage and save interest. Enter loan, rate, term, and overpayments for a private estimate.", "formula": "An overpayment is any amount you pay above the required monthly mortgage payment. Every extra dollar goes straight to the principal, so it shortens the loan term and reduces the total interest you pay.", "example": "On a $300,000 loan at 6.5% over 30 years (a $1,896 monthly payment), adding a $200/month overpayment shortens the term to about 23 years and cuts total interest by roughly $103,000.", "assumptions": [ "The overpayment is applied each month to the principal balance.", "The loan is a fixed-rate amortizing mortgage.", "Interest saved is compared to the base loan with no overpayments." ], "sources": [ { "organization": "Investopedia", "title": "Mortgage Overpayment", "url": "https://www.investopedia.com/terms/m/mortgage-payment.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "Do overpayments reduce interest?", "Yes. Extra principal lowers the balance sooner, so you pay interest on a smaller amount for the remaining term." ], [ "How much does an overpayment save?", "It depends on the rate and when you pay. On a 6.5% 30-year loan, a $200/month overpayment can cut tens of thousands in interest and years off the term." ], [ "Is there a penalty for overpaying?", "Some loans have prepayment penalties or caps. Check your mortgage contract first." ], [ "Should I overpay or invest the money?", "Generally compare the loan rate to your expected investment return. If your mortgage rate is high, paying it down gives a guaranteed, tax-free return equal to that rate. If it's low, you might earn more elsewhere." ], [ "Is a lump sum or monthly overpayment better?", "A lump sum early is best — it reduces the balance before more interest compounds. Monthly overpayments still help but take longer to have the same impact." ], [ "Do overpayments count toward the monthly payment?", "No. The overpayment is in addition to the required payment and goes entirely to principal (unless a lender applies it to a future payment — confirm with them)." ], [ "How does a higher rate change the benefit?", "The higher the rate, the more each overpayment saves in interest. On a low-rate loan (e.g. 3%), the benefit is small." ] ] }, { "slug": "mortgage-payment-calculator", "name": "Mortgage Payment Calculator", "canonical_url": "https://boringtoolskit.com/mortgage-payment-calculator/", "category": "Finance & Investing", "description": "Estimate your monthly mortgage payment including principal, interest, taxes, and insurance. Enter loan amount, rate, and term for a full breakdown. Private.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/mortgage-afford/", "/mortgage-refinance-break-even/", "/loan-comparison-calculator/" ], "answer": "Estimate your monthly mortgage payment including principal, interest, taxes, and insurance. Enter loan amount, rate, and term for a full breakdown. Private.", "formula": "Monthly principal and interest = P × r ÷ (1 − (1+r)^−n); all-in payment adds monthly tax, insurance, PMI estimate, and HOA.", "example": "", "assumptions": [ "Fixed rate and level principal-and-interest payments are assumed.", "Property tax and insurance remain constant.", "PMI cancellation rules, closing costs, utilities, and maintenance are not modeled." ], "sources": [ { "organization": "CFPB", "title": "Explore interest rates and loan options", "url": "https://www.consumerfinance.gov/owning-a-home/explore-rates/" }, { "organization": "HUD", "title": "Buying a home resources", "url": "https://www.hud.gov/buying/loans" } ], "faqs": [ [ "How is a monthly mortgage payment calculated?", "Monthly P&I equals loan principal multiplied by the monthly rate, divided by 1 minus one plus the monthly rate raised to the negative number of payments." ], [ "What does the all-in monthly mortgage payment include?", "It combines monthly principal and interest with the entered property tax, PMI estimate, and homeowners insurance amounts." ], [ "What does a P&I amortization schedule show?", "It shows each scheduled principal-and-interest payment split between interest and principal, along with the remaining loan balance over time." ], [ "Does paying biweekly or adding an extra payment pay the loan off sooner?", "Yes. Because interest accrues on the outstanding balance, paying more than the required amount each month reduces the principal faster and cuts total interest. The Mortgage Overpayment model converts an extra monthly or one-time payment into a shorter term and a lower interest total; biweekly payment is a common way to make 13 payments a year instead of 12." ], [ "Is a 15-year or 30-year term better?", "A 15-year term carries a higher monthly payment but far less total interest, because the balance is paid down faster. Choose based on whether you can comfortably afford the higher payment each month — many buyers prefer a 30-year payment and make extra principal payments when cash flow allows." ], [ "When does PMI drop off and can I cancel it?", "Private mortgage insurance typically cancels once your loan-to-value ratio falls to 20%, either through amortization or by requesting cancellation after the equivalent of 20% equity. Rules differ by loan type, so confirm with your lender; this calculator treats PMI as a flat annual rate on the original loan amount and does not model the cancellation threshold." ], [ "How does down payment size change the monthly payment?", "A larger down payment reduces the loan principal, which lowers the principal-and-interest payment and can remove PMI entirely if you reach a 20% down payment. Use the down-payment input to compare how a bigger upfront sum changes the monthly all-in cost." ] ] }, { "slug": "mortgage-payoff-calculator", "name": "Mortgage Payoff Calculator", "canonical_url": "https://boringtoolskit.com/mortgage-payoff-calculator/", "category": "Finance & Investing", "description": "Mortgage payoff calculator: payoff date and interest saved with extra payments.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "mortgage-refinance-break-even", "name": "Mortgage Refinance Break-Even Calculator", "canonical_url": "https://boringtoolskit.com/mortgage-refinance-break-even/", "category": "Finance & Investing", "description": "Compare old and new mortgage payments and estimate refinance break-even time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/mortgage-payment-calculator/", "/down-payment-calculator/", "/amortization-calculator/" ], "answer": "Compare old and new mortgage payments and estimate refinance break-even time.", "formula": "New payment from the standard amortization formula at the new rate; monthly savings = old payment − new payment; break-even months = total closing costs ÷ monthly savings.", "example": "A $250,000 balance at 7% (30 yr) has a $1,663 payment; refinancing to 6% (30 yr) gives $1,499 — saving $164/month. With $6,000 in closing costs, break-even ≈ 36.5 months.", "assumptions": [ "The balance stays the same (no cash-out).", "The new loan amortizes over the entered term.", "Closing costs are paid upfront and included in the analysis." ], "sources": [ { "organization": "Wikipedia", "title": "Refinancing", "url": "https://en.wikipedia.org/wiki/Refinancing" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is the break-even point in refinancing?", "The months of payment savings needed to recover closing costs: costs ÷ monthly savings. $6,000 ÷ $164 ≈ 37 months." ], [ "When should I refinance?", "When the rate drop is meaningful (0.75–1%+), the savings justify costs, and you'll stay in the home past break-even." ], [ "How do I calculate monthly savings?", "Subtract the new payment from the old: $1,663 − $1,499 = $164/month at 7% → 6% on $250k." ], [ "What are closing costs on a refinance?", "Appraisal, origination, title, and recording fees — typically 2–5% of the loan, or $3,000–$8,000." ], [ "Should I extend the term?", "Extending lowers the payment but adds years of interest — compare total interest, not just the payment." ], [ "What is a cash-out refinance?", "Borrowing more than the balance to take equity out as cash — different math than a rate-and-term refi." ], [ "How do I know if it's worth it?", "Compare break-even months with your expected time in the home. If you'll move before break-even, don't refinance." ], [ "How do I calculate refinance break-even?", "Divide total closing costs by monthly savings: $6,000 ÷ $150 = 40 months." ], [ "How long should I plan to stay?", "Longer than break-even and the refi pays; shorter and it loses — the horizon is the decision." ], [ "Does a lower payment always mean a better loan?", "No — resetting the term can increase total interest even with a lower payment." ], [ "Do points change break-even?", "Yes — points raise closing costs and lengthen break-even; lender credits shorten it." ] ] }, { "slug": "moving-average-calculator", "name": "Moving Average Calculator", "canonical_url": "https://boringtoolskit.com/moving-average-calculator/", "category": "Statistics", "description": "Moving average calculator: simple moving average of a series.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "mulch-calculator", "name": "Mulch Calculator", "canonical_url": "https://boringtoolskit.com/mulch-calculator/", "category": "Construction & Measurement", "description": "Mulch calculator: cubic yards and bags for garden beds.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "mulch-soil-calculator", "name": "Mulch and Soil Calculator", "canonical_url": "https://boringtoolskit.com/mulch-soil-calculator/", "category": "Construction & Measurement", "description": "Estimate cubic yards of mulch or soil from area, depth, and waste allowance.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/square-footage-calculator/", "/concrete-calculator/", "/sonotube-concrete-column/" ], "answer": "Estimate cubic yards of mulch or soil from area, depth, and waste allowance.", "formula": "Volume = length × width × depth (inches) ÷ 12 = cubic feet; cubic yards = cubic feet ÷ 27. Order volume = cubic yards × (1 + waste%). Bags: 1 cu ft bags = total × 27, 1.5 cu ft = total × 18, 2 cu ft = total × 13.5, 3 cu ft = total × 9.", "example": "A 20 × 10 ft bed at 3 in deep: 200 sq ft × 0.25 ft = 50 cu ft ≈ 1.85 cu yd. With 10% waste: ≈ 2.04 cu yd, which is about 28 two-cubic-foot bags.", "assumptions": [ "The bed is rectangular and flat.", "Depth is uniform across the bed.", "Bulk volume is rounded to practical bag counts." ], "sources": [ { "organization": "CalculatorSoup", "title": "Mulch Calculator", "url": "https://www.calculatorsoup.com/calculators/construction/mulch-calculator.php" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How much mulch do I need?", "Multiply length × width × depth (in feet) to get cubic feet, then divide by 27 for cubic yards. A 20×10 ft bed at 3 in needs about 1.85 cu yd." ], [ "How deep should mulch be?", "2–3 inches is typical for garden beds — enough to suppress weeds and retain moisture without smothering plants." ], [ "How many cubic feet are in a cubic yard?", "27 (3 ft × 3 ft × 3 ft). One cubic yard of mulch covers 324 sq ft at 1 inch deep." ], [ "Should I buy bulk or bags?", "Bulk is cheaper for large areas; bags are convenient for small beds and no delivery fee. The tool shows both in bag equivalents." ], [ "Why do I need extra?", "Mulch settles and compacts after watering, and beds are rarely perfectly flat. 10% waste is a reasonable buffer." ], [ "How much does a cubic yard of mulch weigh?", "Varies by type and moisture — bark mulch is roughly 400–800 lb per cubic yard. Check with your supplier for delivery limits." ], [ "Can I use this for soil or gravel?", "Yes — the volume math is the same for any bulk material. Just use the depth appropriate for the project." ], [ "How many bags in a yard?", "About 13.5 bags of 2-cubic-foot mulch." ], [ "Bulk or bags?", "Bulk is cheaper per volume; bags are portable — the calculator shows both." ] ] }, { "slug": "music-interval-calculator", "name": "Music Interval Calculator", "canonical_url": "https://boringtoolskit.com/music-interval-calculator/", "category": "Music & Audio", "description": "Music interval calculator: interval name and semitone distance between two notes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "natural-log-calculator", "name": "Natural Log Calculator", "canonical_url": "https://boringtoolskit.com/natural-log-calculator/", "category": "Everyday Calculators", "description": "Natural log calculator: ln(x) and e^x.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "net-carbs-calculator", "name": "Net Carbs Calculator", "canonical_url": "https://boringtoolskit.com/net-carbs-calculator/", "category": "Food & Cooking", "description": "Net carbs calculator: carbs minus fiber and sugar alcohols.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "net-operating-income-calculator", "name": "Net Operating Income Calculator", "canonical_url": "https://boringtoolskit.com/net-operating-income-calculator/", "category": "Finance & Investing", "description": "Calculate net operating income (NOI) for a rental property. Enter rental income and operating expenses, before the mortgage.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/cap-rate-calculator/", "/debt-service-coverage-ratio-calculator/", "/rental-yield-calculator/" ], "answer": "Calculate net operating income (NOI) for a rental property. Enter rental income and operating expenses, before the mortgage.", "formula": "Net operating income (NOI) = gross operating income (rent + other) − operating expenses (taxes + insurance + maintenance + management + utilities). NOI is the pre-financing, pre-tax profit of a property.", "example": "Gross income $72,000 (rent $70,000 + other $2,000) − operating expenses $22,000 (taxes $8,000 + insurance $3,000 + maintenance $6,000 + management $3,600 + utilities $1,400) = NOI $50,000.", "assumptions": [ "Income and expenses are entered annually.", "Operating expenses exclude debt service and capital expenditures.", "Vacancy and management fees should reflect realistic market rates." ], "sources": [ { "organization": "Investopedia", "title": "Net Operating Income", "url": "https://www.investopedia.com/terms/n/noi.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is included in NOI?", "Gross rent plus other income minus operating expenses: taxes, insurance, maintenance, management, and utilities the owner pays." ], [ "What is NOT included in NOI?", "Debt service (mortgage), income taxes, and capital expenditures. Those come after NOI." ], [ "Why is NOI important?", "It's the numerator of cap rate and the basis of DSCR — the two most-used metrics for valuing and financing income property." ], [ "How do I find my property's NOI?", "Start from annual gross income, subtract all recurring operating costs. Use real figures from your operating statement." ], [ "Is a higher NOI always better?", "Yes — higher NOI on the same value means a higher cap rate and more-bankable income. But quality matters: sustainable NOI beats one-time gains." ], [ "Do I subtract the mortgage?", "No. NOI is before debt service. The mortgage is covered by cash flow, not NOI." ], [ "How does NOI affect property value?", "Value ≈ NOI ÷ cap rate. If NOI rises and cap rate stays flat, value rises." ] ] }, { "slug": "net-present-value-calculator", "name": "Net Present Value Calculator", "canonical_url": "https://boringtoolskit.com/net-present-value-calculator/", "category": "Finance & Investing", "description": "Net present value calculator: NPV of a yearly cash flow at a discount rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "net-worth-calculator", "name": "Net Worth Calculator", "canonical_url": "https://boringtoolskit.com/net-worth-calculator/", "category": "Everyday Calculators", "description": "Add up your assets and liabilities to find your net worth.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/savings-goal-calculator/", "/debt-payoff/", "/compound-interest/" ], "answer": "Add up your assets and liabilities to find your net worth.", "formula": "Net worth = total assets − total liabilities. The calculator sums your entered asset lines (cash, investments, property) and subtracts your liabilities (loans, credit cards, mortgage balance) to give a single balance-sheet number.", "example": "A person with $320,000 in assets and $180,000 in liabilities has a net worth of $320,000 − $180,000 = $140,000.", "assumptions": [ "Assets and liabilities are entered by the user as 'label, amount' lines.", "Asset values are current market values (not what you paid).", "The result is a point-in-time snapshot." ], "sources": [ { "organization": "Investopedia", "title": "Net Worth", "url": "https://www.investopedia.com/terms/n/networth.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate net worth?", "Net worth = total assets − total liabilities." ], [ "What counts as an asset?", "Cash, savings, investments, real estate, vehicles, and anything else you own that has value. Include the current market value, not what you paid." ], [ "What counts as a liability?", "Mortgage balance, car loans, student loans, credit card debt, personal loans, and any other money you owe." ], [ "Does a mortgage count against net worth?", "Yes, the remaining balance is a liability. But the home's value is an asset, so the net (home value − mortgage) adds to net worth." ], [ "Is a high income the same as high net worth?", "No. Income is what you earn; net worth is what you've accumulated. You can have a high income and low net worth, or vice versa." ], [ "How often should I check it?", "Periodically (quarterly or yearly) to track the trend. The direction over time matters more than any single number." ], [ "Why is net worth useful?", "It's the cleanest measure of financial progress. Watching it grow — via paying down debt and investing — is the core of building wealth." ] ] }, { "slug": "normal-distribution-probability-calculator", "name": "Normal Distribution Probability Calculator", "canonical_url": "https://boringtoolskit.com/normal-distribution-probability-calculator/", "category": "Statistics", "description": "Normal distribution probability calculator: area under the curve for a value, above a value, or between two values.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "nth-root-calculator", "name": "Nth Root Calculator", "canonical_url": "https://boringtoolskit.com/nth-root-calculator/", "category": "Everyday Calculators", "description": "Nth root calculator: the n-th root of a number.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "numbers-to-words", "name": "Numbers to Words Converter", "canonical_url": "https://boringtoolskit.com/numbers-to-words/", "category": "Everyday Calculators", "description": "Convert any whole number into English words , for checks, contracts, and homework.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/rounding-numbers-calculator/", "/order-of-operations-calculator/", "/random-number-generator/" ], "answer": "Convert any whole number into English words , for checks, contracts, and homework.", "formula": "Converts an integer (0–999,999,999,999) into English words using the standard grouping by thousands.", "example": "1,234 reads 'one thousand two hundred thirty-four'.", "assumptions": [ "US short-scale naming applies.", "Whole numbers only within the stated range.", "Standard English hyphenation rules are used." ], "sources": [ { "organization": "Wikipedia", "title": "English numerals", "url": "https://en.wikipedia.org/wiki/English_numerals" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I write a number in words?", "Group by thousands and name each group: 1,234 = 'one thousand two hundred thirty-four'." ], [ "What range does it support?", "0 to 999,999,999,999 (whole numbers)." ], [ "How do I write 1001?", "'One thousand one' — no 'and' in US convention." ], [ "Do I hyphenate compounds?", "Yes — twenty-four, thirty-five, per standard convention." ], [ "Why is a billion different in some countries?", "The UK historically used the long scale (a billion = a million million); the US short scale (a thousand million) is now common." ], [ "Can I convert decimals?", "No — whole numbers only. For money, add cents separately." ], [ "What is this used for?", "Checks, invoices, legal amounts, and text where numbers are spelled out." ] ] }, { "slug": "numerology-life-path-calculator", "name": "Numerology Life Path Calculator", "canonical_url": "https://boringtoolskit.com/numerology-life-path-calculator/", "category": "Astrology", "description": "Numerology life path calculator: reduce a birth date to its life path number, master numbers kept.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "numerology-name-number-calculator", "name": "Numerology Name Number Calculator", "canonical_url": "https://boringtoolskit.com/numerology-name-number-calculator/", "category": "Astrology", "description": "Numerology name number calculator: Pythagorean letter values for any name, entertainment only.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "octal-converter", "name": "Octal Converter", "canonical_url": "https://boringtoolskit.com/octal-converter/", "category": "Converters", "description": "Octal converter: decimal, binary, octal and hex.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "odds-ratio-calculator", "name": "Odds Ratio Calculator", "canonical_url": "https://boringtoolskit.com/odds-ratio-calculator/", "category": "Statistics", "description": "Odds ratio calculator: association from a 2x2 table.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "ohms-law-calculator", "name": "Ohm's Law Calculator", "canonical_url": "https://boringtoolskit.com/ohms-law-calculator/", "category": "Everyday Calculators", "description": "Calculate voltage, current, resistance, or power using Ohm's law.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/voltage-drop-calculator/", "/watts-to-amps-calculator/", "/battery-runtime-calculator/" ], "answer": "Calculate voltage, current, resistance, or power using Ohm's law.", "formula": "Ohm's law: V = I × R (voltage = current × resistance). Derived: I = V ÷ R, R = V ÷ I. Power: P = V × I (watts).", "example": "A 12 V supply across a 4 Ω resistor: current I = 12 ÷ 4 = 3 A, and power P = 12 × 3 = 36 W.", "assumptions": [ "The component is ohmic (linear resistance).", "DC or RMS AC values are used.", "Temperature effects on resistance are ignored." ], "sources": [ { "organization": "Wikipedia", "title": "Ohm's law", "url": "https://en.wikipedia.org/wiki/Ohm%27s_law" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is Ohm's law?", "V = I × R: voltage equals current times resistance. It's the fundamental relationship in electrical circuits." ], [ "How do I calculate current?", "I = V ÷ R. 12 V across 4 Ω gives 3 A." ], [ "What is power in a circuit?", "P = V × I (watts). The same 12 V at 3 A dissipates 36 W — heat you must size the resistor for." ], [ "Does Ohm's law apply to everything?", "No — it applies to ohmic components like resistors and wires. Diodes, LEDs, and semiconductors have nonlinear current-voltage behavior." ], [ "What happens if a resistor overheats?", "Resistance changes with temperature, so the linear relationship drifts. That's why power ratings matter: an undersized resistor burns out." ], [ "What's the difference between AC and DC?", "DC is steady; AC alternates. For AC with reactive components (capacitors, inductors), impedance replaces resistance and phase matters." ], [ "How do I size a series resistor for an LED?", "R = (supply voltage − LED forward voltage) ÷ desired current. For a 5 V supply, 2 V LED, 20 mA: R = 3 ÷ 0.02 = 150 Ω." ], [ "How do I find current?", "I = V ÷ R: 12 V ÷ 4 Ω = 3 A." ], [ "How is power related?", "P = V × I, or I²R — the load's power draw." ], [ "Does it work for AC?", "With impedance instead of resistance for reactive components." ] ] }, { "slug": "on-call-pay-calculator", "name": "On Call Pay Calculator", "canonical_url": "https://boringtoolskit.com/on-call-pay-calculator/", "category": "Time & Work", "description": "On call pay calculator: compensation for on-call hours.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "one-rep-max-calculator", "name": "One Rep Max Calculator", "canonical_url": "https://boringtoolskit.com/one-rep-max-calculator/", "category": "Everyday Calculators", "description": "Estimate your one-rep max from a submaximal lift.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/calories-burned-calculator/", "/bmr-tdee-calculator/", "/pace-calculator/" ], "answer": "Estimate your one-rep max from a submaximal lift.", "formula": "Estimated one-rep max (Epley formula): 1RM = weight × (1 + reps ÷ 30). 95% of max ≈ 1RM × 0.95.", "example": "Lifting 185 lb for 5 reps: estimated 1RM = 185 × (1 + 5 ÷ 30) = 185 × 1.1667 ≈ 216 lb; 95% ≈ 205 lb.", "assumptions": [ "The set was performed to near failure with good form.", "The lift is a compound barbell movement.", "The trainee is experienced enough to train near maximal loads." ], "sources": [ { "organization": "ACE Fitness", "title": "Tools & Calculators (strength)", "url": "https://www.acefitness.org/resources/everyone/tools-calculators/" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How is one-rep max estimated?", "The Epley formula: 1RM = weight × (1 + reps ÷ 30). 185 lb for 5 reps estimates a 216 lb max." ], [ "What is the Epley formula?", "A widely used prediction: estimated max = lifted weight × (1 + reps ÷ 30). It's simple and accurate for low-rep sets." ], [ "How many reps should I use for the test?", "3–8 reps is the sweet spot. Very high rep sets make the estimate unreliable and the set itself fatiguing." ], [ "Why not just test a real 1RM?", "True max attempts carry injury risk and need heavy warm-ups and a spotter. Submaximal estimates give you the programming number safely." ], [ "What is the 95% figure?", "A common working top-end percentage (95% of max) used for heavy training days. Many programs cap working sets around there." ], [ "Does this work for every lift?", "Best for compound lifts like squat, bench, and deadlift. Isolation exercises and machines may estimate differently." ], [ "How often should I retest?", "Every 4–8 weeks as strength changes. Use the same formula each time so progress is comparable." ] ] }, { "slug": "orbital-period-calculator", "name": "Orbital Period Calculator", "canonical_url": "https://boringtoolskit.com/orbital-period-calculator/", "category": "Astronomy", "description": "Orbital period calculator: circular orbit period around Earth from altitude (Kepler).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "order-of-operations-calculator", "name": "Order of Operations Calculator (PEMDAS)", "canonical_url": "https://boringtoolskit.com/order-of-operations-calculator/", "category": "Everyday Calculators", "description": "Evaluate math expressions with the correct order of operations (PEMDAS): parentheses, exponents, multiplication and division, then addition and subtraction.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "August 2026", "related_urls": [ "/percentage-calc/", "/general-scientific-calculator/", "/combinations-calculator/" ], "answer": "Evaluate math expressions with the correct order of operations (PEMDAS): parentheses, exponents, multiplication and division, then addition and subtraction.", "formula": "The calculator tokenizes the expression and evaluates it with standard precedence: parentheses group first, exponents next, multiplication and division left to right, then addition and subtraction left to right.", "example": "2 + 3 × 4 evaluates to 14, because multiplication is performed before addition.", "assumptions": [ "Interpretation uses standard arithmetic precedence (PEMDAS).", "Division by zero and unbalanced parentheses are reported as invalid.", "Only numbers and the operators + − × ÷ ( ) are accepted." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculation methodology and verification standard", "url": "/methodology/" } ], "faqs": [ [ "What is the order of operations (PEMDAS)?", "The order is parentheses, exponents, multiplication and division (left to right), then addition and subtraction (left to right). This calculator applies that standard to evaluate an expression." ], [ "Why does 2 + 3 × 4 equal 14 and not 20?", "Multiplication happens before addition, so 3 × 4 = 12 is computed first, then 2 + 12 = 14. The calculator follows the same rule." ], [ "Can this calculator handle negative numbers and parentheses?", "Yes. It accepts +, −, ×, ÷, parentheses, decimals, and negative signs. Use × or * for multiplication and ÷ or / for division." ] ] }, { "slug": "outlier-calculator", "name": "Outlier Calculator", "canonical_url": "https://boringtoolskit.com/outlier-calculator/", "category": "Statistics", "description": "Outlier calculator: flag outliers by the 1.5x IQR rule.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "oven-conversion-calculator", "name": "Oven Conversion Calculator", "canonical_url": "https://boringtoolskit.com/oven-conversion-calculator/", "category": "Food & Cooking", "description": "Oven conversion calculator: conventional to convection.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "oven-temperature-converter", "name": "Oven Temperature Converter", "canonical_url": "https://boringtoolskit.com/oven-temperature-converter/", "category": "Food & Cooking", "description": "Oven temperature converter: Fahrenheit, Celsius, and UK gas marks.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "overtime-calculator", "name": "Overtime Calculator", "canonical_url": "https://boringtoolskit.com/overtime-calculator/", "category": "Time & Work", "description": "Estimate regular and overtime pay with editable thresholds and overtime multipliers.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/time-card-calculator/", "/shift-differential-calculator/", "/paycheck-calc/" ], "answer": "Estimate regular and overtime pay with editable thresholds and overtime multipliers.", "formula": "Regular hours = min(worked, threshold). Overtime hours = max(0, worked − threshold). Pay = regular × rate + overtime × rate × multiplier (typically 1.5×).", "example": "45 hours at $20/hr with a 40-hour threshold at 1.5×: regular $800 + overtime $150 = $950.", "assumptions": [ "The employee is non-exempt.", "One overtime threshold applies.", "The multiplier matches the employer's policy (1.5× typical)." ], "sources": [ { "organization": "Wikipedia", "title": "Overtime", "url": "https://en.wikipedia.org/wiki/Overtime" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How is overtime paid?", "At 1.5× your base rate for hours over the threshold — usually 40/week. 5 hours at $20 × 1.5 = $150." ], [ "What is the overtime threshold?", "40 hours per week under federal law; some states also require daily overtime after 8 hours." ], [ "Am I entitled to overtime?", "Non-exempt hourly and salaried workers qualify; exempt employees (executive, professional, certain roles) don't." ], [ "What is double time?", "2× pay, required in some states for very long shifts or seventh-day work." ], [ "How do I verify my paycheck?", "Split your hours at the threshold, calculate regular and OT pay, and compare to gross." ], [ "Can my employer deny overtime?", "No — for non-exempt workers, working the hours obligates pay at the overtime rate. Unauthorized OT can be disciplined but not unpaid." ], [ "What's a shift differential?", "Extra pay for undesirable shifts (nights, weekends) — a different premium from overtime." ] ] }, { "slug": "ovulation-calculator", "name": "Ovulation Calculator", "canonical_url": "https://boringtoolskit.com/ovulation-calculator/", "category": "Everyday Calculators", "description": "Estimate your fertile window and ovulation date based on cycle length and last period.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/due-date-calculator/", "/pregnancy-calculator/", "/ideal-weight-calculator/" ], "answer": "Estimate your fertile window and ovulation date based on cycle length and last period.", "formula": "Ovulation date = period start + (cycle length − 14). Fertile window = ovulation − 5 days to ovulation + 1 day. Next period = period start + cycle length. Based on the standard assumption that ovulation occurs ~14 days before the next period.", "example": "With a 28-day cycle and a period starting May 1: ovulation = May 1 + 14 = May 15; fertile window = May 10–16; next period ≈ May 29.", "assumptions": [ "Ovulation occurs about 14 days before the next period.", "The entered cycle length is a stable average.", "Luteal phase length is the typical 14 days." ], "sources": [ { "organization": "ACOG", "title": "Fertility Awareness-Based Methods of Family Planning", "url": "https://www.acog.org/womens-health/faqs/fertility-awareness-based-methods-of-family-planning" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "When do I ovulate?", "About 14 days before your next expected period. With a 28-day cycle, that's roughly day 14. The calculator estimates this from your cycle length." ], [ "What is the fertile window?", "The days you're most likely to conceive — about 5 days before ovulation through 1 day after, because sperm survive several days." ], [ "How accurate is this method?", "Good for regular cycles, less reliable for irregular ones. Stress, travel, illness, and hormonal changes shift ovulation." ], [ "Can I use this to avoid pregnancy?", "Fertility awareness requires rigorous tracking and isn't as reliable as other methods. Use it with caution and confirm with ovulation tests." ], [ "What if my cycle is irregular?", "The estimate is only as good as the cycle length you enter. Track several months and consider ovulation predictor kits." ], [ "When should I take a pregnancy test?", "About 14 days after predicted ovulation (or the first day of a missed period) for the most reliable result." ], [ "Does cycle length affect the fertile window?", "Yes — longer cycles ovulate later, shorter cycles earlier. The calculator shifts the window to match your cycle length." ], [ "How long is the fertile window?", "About 6 days: 5 days before ovulation plus ovulation day." ], [ "Is the calendar method reliable?", "As an estimate, yes; as contraception, no — cycles vary." ] ] }, { "slug": "p-value-calculator", "name": "P Value Calculator", "canonical_url": "https://boringtoolskit.com/p-value-calculator/", "category": "Statistics", "description": "P value calculator: two-tailed p-value from a z-score.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "pace-calculator", "name": "Pace Calculator", "canonical_url": "https://boringtoolskit.com/pace-calculator/", "category": "Health", "description": "Calculate your running pace per km or mile from distance and time, plus speed and predicted race times.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/one-rep-max-calculator/", "/calories-burned-calculator/", "/time-to-decimal-calculator/" ], "answer": "Calculate your running pace per km or mile from distance and time, plus speed and predicted race times.", "formula": "Pace = total time ÷ distance. Total time = hours×3600 + minutes×60 + seconds (seconds). Pace per unit = total seconds ÷ distance, formatted as mm:ss per mile or kilometer.", "example": "Running 5 km in 30 minutes: pace = 30 ÷ 5 = 6 minutes per kilometer (6:00/km).", "assumptions": [ "The pace is constant across the distance.", "Time and distance are entered accurately.", "The result is an average, not instantaneous, pace." ], "sources": [ { "organization": "CalculatorSoup", "title": "Pace Calculator", "url": "https://www.calculatorsoup.com/calculators/health/pace-calculator.php" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate my pace?", "Divide total time by distance: 30 minutes ÷ 5 km = 6:00 per km. The tool formats it as mm:ss." ], [ "What's a good running pace?", "It depends on fitness and distance — a 10:00/mile is a comfortable jog for many; competitive runners hold 6:00–7:00/mile. Compare against your own previous efforts." ], [ "What's the difference between pace and speed?", "Pace is time per distance (min/mile); speed is distance per time (mph or km/h). They're inverses: 6:00/km ≈ 10 km/h." ], [ "How do I convert pace to speed?", "Divide 60 by the pace in minutes: 6:00/km → 60 ÷ 6 = 10 km/h. For miles: 60 ÷ 8:00 = 7.5 mph." ], [ "How do I hit a goal finish time?", "Work backward: goal time ÷ distance = required pace. For a 50-minute 10 km, you need 5:00/km average." ], [ "Why does elevation matter?", "Hillier routes take longer at the same effort — your pace will vary. Track pace adjusted for elevation gain (GAP) if your watch supports it." ], [ "Does the tool include stops?", "No — it uses total moving time if that's what you enter. Including stopped time gives a slower average pace." ], [ "What is running pace?", "Time per mile or kilometer — the runner's standard effort metric." ], [ "How do I calculate pace?", "Time ÷ distance: 50 min ÷ 10 km = 5:00/km." ], [ "What pace for a target race time?", "Goal time ÷ race distance — the calculator returns the per-mile target." ], [ "What is a good easy-run pace?", "About 1–2 minutes per mile slower than race pace." ] ] }, { "slug": "packing-weight-calculator", "name": "Packing Weight Calculator", "canonical_url": "https://boringtoolskit.com/packing-weight-calculator/", "category": "Travel", "description": "Packing weight calculator: total luggage weight from item counts and typical weights.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "paint-calculator", "name": "Paint Calculator", "canonical_url": "https://boringtoolskit.com/paint-calculator/", "category": "Construction & Measurement", "description": "Estimate how many gallons of paint you need for walls, doors, and trim. Covers two coats and accounts for waste.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "paint-cost-per-square-foot", "name": "Paint Cost Per Square Foot Calculator", "canonical_url": "https://boringtoolskit.com/paint-cost-per-square-foot/", "category": "Everyday Calculators", "description": "Estimate paint cost per square foot or the total to paint a room from your own rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/paint-coverage-calculator/", "/square-footage-calculator/", "/drywall-calculator/" ], "answer": "Estimate paint cost per square foot or the total to paint a room from your own rate.", "formula": "Material cost per sq ft = paint rate per sq ft × number of coats. Total = area × per-sq-ft cost + labor.", "example": "At $0.15/sq ft per coat, two coats on 2,000 sq ft = $600 in materials; with $500 labor, the total is $1,100.", "assumptions": [ "Flat, accessible surfaces.", "Coverage matches the paint's rated rate.", "Prep work is included in labor or separate." ], "sources": [ { "organization": "Wikipedia", "title": "House painting", "url": "https://en.wikipedia.org/wiki/House_painting" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I estimate paint cost?", "Area × rate per sq ft × coats + labor: 2,000 × $0.15 × 2 + $500 = $1,100." ], [ "How much area does a gallon cover?", "About 350–400 sq ft per coat for most quality paints." ], [ "How many coats do I need?", "Two for most color changes and bare surfaces; one for same-color touch-ups." ], [ "What's the typical cost per sq ft?", "$0.10–0.25 per sq ft per coat for materials, plus labor of $1–3/sq ft depending on region and prep." ], [ "Does this include prep?", "No — spackling, priming, and taping are usually priced separately in quotes." ], [ "Why is my quote higher?", "Trim, ceilings, texture, height, and prep all add cost beyond a flat-wall estimate." ], [ "Should I DIY or hire?", "Compare your materials + time against the quote — and remember labor is the largest line item." ], [ "How much does painting cost per square foot?", "$1–3/sq ft all-in for interiors, more with prep and premium finishes." ], [ "How do I compare quotes?", "Convert each to $/sq ft: $3,000 ÷ 1,500 = $2.00/sq ft." ], [ "What drives the rate?", "Scope (walls vs ceilings/trim), prep, repairs, and paint quality." ], [ "Is material or labor bigger?", "Labor is typically the larger share of a pro quote." ] ] }, { "slug": "paint-coverage-calculator", "name": "Paint Coverage Calculator", "canonical_url": "https://boringtoolskit.com/paint-coverage-calculator/", "category": "Construction & Measurement", "description": "Estimate paintable wall area and gallons needed after subtracting doors and windows.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/square-footage-calculator/", "/flooring-calculator/", "/tile-calculator/" ], "answer": "Estimate paintable wall area and gallons needed after subtracting doors and windows.", "formula": "Gross wall area = perimeter × wall height. Openings = doors × 20 + windows × 15 sq ft. Paintable area = max(0, gross − openings). Coated area = paintable area × coats. Gallons = ceil(coated area ÷ coverage per gallon).", "example": "A room with 60 ft of wall perimeter and 10 ft walls: gross = 600 sq ft. Subtract 2 doors (40) and 3 windows (45) → 515 sq ft paintable. Two coats = 1,030 sq ft; at 350 sq ft/gallon → ceil(1030 ÷ 350) = 3 gallons.", "assumptions": [ "Openings average 20 sq ft per door and 15 sq ft per window.", "A gallon covers the entered coverage (350 sq ft is typical).", "Walls are smooth and already primed." ], "sources": [ { "organization": "Bob Vila", "title": "How Much Paint Do I Need?", "url": "https://www.bobvila.com/articles/how-much-paint-do-i-need/" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How much paint do I need for a room?", "Compute wall area (perimeter × height), subtract doors and windows, multiply by coats, and divide by the coverage per gallon. A typical 12×15 ft room with two coats needs about 2–3 gallons." ], [ "How many square feet does a gallon cover?", "About 350 sq ft per coat for smooth, primed walls. Textured or very porous surfaces cover less." ], [ "Why subtract doors and windows?", "They aren't painted with wall color, so subtracting avoids over-buying. This tool uses 20 sq ft per door and 15 sq ft per window." ], [ "How many coats do I need?", "Two is standard. Dark-to-light color changes or bare drywall may need three; a same-color repaint can need one." ], [ "Does this include the ceiling?", "No — ceilings, trim, and doors are separate painting jobs with their own area calculations." ], [ "Should I buy extra?", "Yes — keep leftover paint for touch-ups. Rounding up to whole gallons usually provides enough margin." ], [ "Why does my painter's estimate differ?", "Painters account for texture, trim, spray loss, and brand-specific coverage. Use this as a planning number and confirm with your painter." ], [ "How much paint do I need?", "Wall area ÷ 350 sq ft per gallon × number of coats." ], [ "Do I need two coats?", "Usually yes for even color and durability; one coat is for touch-ups." ], [ "Do windows and doors reduce the count?", "Yes — subtract their area or let the waste allowance absorb it." ] ] }, { "slug": "parallelogram-area-calculator", "name": "Parallelogram Area Calculator", "canonical_url": "https://boringtoolskit.com/parallelogram-area-calculator/", "category": "Everyday Calculators", "description": "Parallelogram area calculator: area from base and height.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-27", "related_urls": [], "answer": "Parallelogram area calculator: area from base and height.", "formula": "Area = base × height (the perpendicular height, not the side length).", "example": "Base 8 m, height 3 m → area 24 m².", "assumptions": [ "Standard geometric or arithmetic definitions apply.", "Inputs use the units you choose.", "Results are estimates, not professional advice." ], "sources": [ { "organization": "Standard mathematics definitions", "title": "Arithmetic and geometry formulas", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "parking-cost-calculator", "name": "Parking Cost Calculator", "canonical_url": "https://boringtoolskit.com/parking-cost-calculator/", "category": "Travel", "description": "Parking cost calculator: daily vs monthly pass comparison for commuters.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "parlay-odds-calculator", "name": "Parlay Odds Calculator", "canonical_url": "https://boringtoolskit.com/parlay-odds-calculator/", "category": "Gaming", "description": "Parlay odds calculator: combined odds and implied probability for multi-leg bets.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "passer-rating-calculator", "name": "NFL Passer Rating Calculator", "canonical_url": "https://boringtoolskit.com/passer-rating-calculator/", "category": "Sports", "description": "NFL passer rating calculator: QB rating from attempts, completions, yards, touchdowns, and interceptions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "password-generator", "name": "Password Generator", "canonical_url": "https://boringtoolskit.com/password-generator/", "category": "Text & Developer Tools", "description": "Generate strong random passwords with configurable length and character sets, with entropy and strength rating. Local and private.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/random-number-generator/", "/qr-generator/", "/base64-tool/" ], "answer": "Generate strong random passwords with configurable length and character sets, with entropy and strength rating. Local and private.", "formula": "Passwords are generated by randomly selecting characters from the enabled sets (lowercase, uppercase, digits, symbols), length 6–64. Entropy = length × log₂(character-set size): a 16-character password from 94 printable characters has ≈ 105 bits of entropy.", "example": "A 16-character password using all four character classes (94 possible characters) has 16 × log₂(94) ≈ 105 bits of entropy — strong against brute force.", "assumptions": [ "Generation uses a cryptographically random source in the browser.", "The password is stored and managed securely by the user.", "Entropy assumes random, uniform character selection." ], "sources": [ { "organization": "NIST", "title": "SP 800-63B — Digital Identity Guidelines (password recommendations)", "url": "https://pages.nist.gov/800-63-3/sp800-63b.html" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How long should a password be?", "16 characters or more is a strong default. Length matters more than complexity — each extra character multiplies the possible combinations." ], [ "What is password entropy?", "A measure of unpredictability in bits: length × log₂(character-set size). A 16-character password from 94 characters has about 105 bits — astronomically hard to brute force." ], [ "Should I include symbols?", "They add entropy, but length matters more. A 16-character lowercase password is stronger than an 8-character one with symbols." ], [ "Is it safe to generate passwords in the browser?", "Yes — the tool generates locally and nothing is transmitted. The bigger risk is how you store the password afterward." ], [ "Why not reuse the same strong password?", "One breached site exposes every account using that password. Use a unique password per site via a password manager." ], [ "What about password managers?", "Recommended: they store unique random passwords and autofill them, so you only need to remember one master password." ], [ "What does NIST recommend?", "NIST SP 800-63B now emphasizes length and uniqueness over forced complexity rules, and recommends screening against known breached passwords." ] ] }, { "slug": "patio-paver-calculator", "name": "Patio Paver Calculator", "canonical_url": "https://boringtoolskit.com/patio-paver-calculator/", "category": "Construction & Measurement", "description": "Patio paver calculator: pavers needed with waste.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "paver-calculator", "name": "Paver Calculator", "canonical_url": "https://boringtoolskit.com/paver-calculator/", "category": "Construction & Measurement", "description": "Estimate paver count, base aggregate, bedding sand, waste, and optional paver cost.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/gravel-calculator/", "/tile-calculator/", "/concrete-calculator/" ], "answer": "Estimate paver count, base aggregate, bedding sand, waste, and optional paver cost.", "formula": "Pavers = ceiling(project area ÷ paver face area × (1 + waste)); base and sand volume = area × depth ÷ 27.", "example": "", "assumptions": [ "Paver dimensions are nominal face dimensions and joints are not separately modeled.", "Base and bedding depths are uncompacted planning inputs.", "Edging, joint sand, drainage, labor, and delivery are excluded." ], "sources": [ { "organization": "ICPI/CMHA", "title": "Concrete paver installation resources", "url": "https://www.cmha.org/" }, { "organization": "NIST", "title": "SI units and conversions", "url": "https://www.nist.gov/pml/owm/metric-si/si-units" } ], "faqs": [ [ "What is a paver calculator and how does it work?", "A paver calculator is a browser-based tool that estimates the number of pavers and amount of base material you need for your project. You enter your area dimensions and paver size, and it instantly calculates the results right in your browser—no signup required." ], [ "Do I need to create an account or sign up to use the paver calculator?", "No. The paver calculator is completely free, no-signup, and runs entirely in your browser. Your measurements are never stored or shared." ], [ "How accurate is the paver calculator for my project?", "The paver calculator gives a reliable estimate based on your entered dimensions and paver size. For best results, measure your area carefully and add a 5–10% overage for cuts and waste." ] ] }, { "slug": "pay-raise-calculator", "name": "Salary Raise Calculator", "canonical_url": "https://boringtoolskit.com/pay-raise-calculator/", "category": "Finance & Investing", "description": "Convert a pay raise into new annual, monthly, weekly, and hourly compensation.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/salary-hourly-converter/", "/paycheck-calc/", "/overtime-calculator/" ], "answer": "Convert a pay raise into new annual, monthly, weekly, and hourly compensation.", "formula": "Raise amount = current pay × raise percentage; new pay = current pay + raise amount.", "example": "", "assumptions": [ "Current pay is treated as annual gross compensation.", "Hourly equivalent uses the entered paid weeks and hours.", "Taxes, benefits, bonuses, and inflation are excluded." ], "sources": [ { "organization": "BLS", "title": "Employee compensation information", "url": "https://www.bls.gov/ncs/" }, { "organization": "Department of Labor", "title": "Wages resources", "url": "https://www.dol.gov/general/topic/wages" } ], "faqs": [ [ "How does this pay raise calculator work?", "It's a simple browser-based tool where you enter your current salary and the raise percentage or amount. It instantly calculates your new salary, the raise dollar value, and the percentage increase — all processed locally on your device with no data sent to any server." ], [ "Do I need to create an account or sign up to use the pay raise calculator?", "No. This is a completely no-signup tool that runs entirely in your browser. You can use it immediately without providing any personal information, email address, or credentials." ], [ "Is my data safe when using the pay raise calculator?", "Yes. Since the pay raise calculator runs entirely in your browser, your salary details and inputs are never stored, transmitted, or shared with any server. Everything is processed locally and disappears the moment you close the page." ] ] }, { "slug": "paycheck-calc", "name": "Paycheck After Tax Calculator", "canonical_url": "https://boringtoolskit.com/paycheck-calc/", "category": "Finance & Investing", "description": "Estimate 2026 federal and FICA withholding with clearly labeled state planning estimates.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/time-card-calculator/", "/overtime-calculator/", "/salary-hourly-converter/" ], "answer": "Estimate 2026 federal and FICA withholding with clearly labeled state planning estimates.", "formula": "Gross pay = hours × rate (plus overtime) or salary. Deductions: federal income tax (standard deduction and brackets), FICA (Social Security 6.2% + Medicare 1.45%), and state income tax by state. Net pay = gross − deductions.", "example": "A $25/hr worker earning 40 hours biweekly has ~$2,000 gross; after federal, FICA (~7.65%), and state tax, net is roughly $1,650–$1,750 depending on the state.", "assumptions": [ "Federal standard deduction and current brackets apply.", "No pre-tax benefits (401k, insurance) are deducted.", "The state tax table reflects the selected state's rates." ], "sources": [ { "organization": "Wikipedia", "title": "Paycheck", "url": "https://en.wikipedia.org/wiki/Paycheck" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How is take-home pay calculated?", "Net = gross minus federal income tax, FICA (7.65%), and state income tax. The tool walks through each." ], [ "What is FICA?", "Payroll taxes: 6.2% Social Security plus 1.45% Medicare — matched by your employer." ], [ "How much tax comes out of a $2,000 paycheck?", "Roughly 12–17% for federal/state combined at typical incomes — around $250–$350, depending on state and filing status." ], [ "Why does my state change the number?", "State income tax rates range from 0% (TX, FL) to over 13% top brackets (CA) — the tool applies each state's table." ], [ "Does this include my 401(k)?", "No — pre-tax contributions lower taxable income. Add them mentally or check your paystub." ], [ "How accurate is this?", "Close for typical W-2 situations with the standard deduction, but your W-4, benefits, and credits adjust the exact number." ], [ "How do I use this for a job offer?", "Compare net pay (after tax) between offers, not gross — state taxes alone can swing the difference." ] ] }, { "slug": "payload-towing-calculator", "name": "Payload and Towing Calculator", "canonical_url": "https://boringtoolskit.com/payload-towing-calculator/", "category": "Vehicles", "description": "Payload and towing calculator: remaining payload from GVWR, curb weight, passengers, and cargo.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "payment-fee-calculator", "name": "PayPal & Stripe Fee Calculator", "canonical_url": "https://boringtoolskit.com/payment-fee-calculator/", "category": "Seller & Business", "description": "Calculate PayPal and Stripe fees, net proceeds, or the amount to charge. Use editable presets for Stripe 2.9% + $0.30 and PayPal 3.49% + $0.49.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/etsy-fee-profit/", "/profit-margin-markup-calculator/", "/percentage-markup-calculator/" ], "answer": "Calculate PayPal and Stripe fees, net proceeds, or the amount to charge. Use editable presets for Stripe 2.9% + $0.30 and PayPal 3.49% + $0.49.", "formula": "Processing fee = amount × percentage fee + fixed fee. The calculator applies a percentage and a fixed per-transaction cost (with presets for Stripe and PayPal) to a sale amount, plus any custom fee, to show what the seller nets.", "example": "A $100 sale at Stripe's 2.9% + $0.30 fee: fee = $2.90 + $0.30 = $3.20, so the seller nets $96.80.", "assumptions": [ "Fee is a percentage of the sale plus a fixed per-transaction cost.", "Presets reflect standard online rates (Stripe, PayPal) — your actual rate may vary.", "The result is the merchant's net after the processing fee." ], "sources": [ { "organization": "Investopedia", "title": "Payment Processing Fee", "url": "https://www.investopedia.com/terms/p/payment-fee.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How is a payment fee calculated?", "Fee = sale amount × percentage fee + fixed fee. Net proceeds = sale amount − fee." ], [ "What are Stripe's fees?", "Standard online card rate is roughly 2.9% + $0.30 per transaction, though it varies by country and volume." ], [ "What are PayPal's fees?", "Roughly 3.49% + $0.49 for standard commerce transactions, again varying by country and payment method." ], [ "Do I pay the fee or the customer?", "The merchant (you) pays the processing fee. You can price it into the product so the customer effectively covers it." ], [ "What is the fixed fee?", "A flat per-transaction charge (e.g. $0.30) added to the percentage. It hits small sales proportionally harder." ], [ "Are there other fees?", "Possibly — chargebacks, currency conversion, monthly fees, or fees for certain card types. Check your processor's full rate card." ], [ "Which processor is cheaper?", "It depends on your volume and average sale. Compare true rates (percentage + fixed) against your typical sale amount. Both have tiers." ] ] }, { "slug": "payment-terms-generator", "name": "Payment Terms Generator", "canonical_url": "https://boringtoolskit.com/payment-terms-generator/", "category": "Generators", "description": "Draft plain-language payment terms for invoices, quotes, retainers, deposits, late fees, and due dates.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/invoice-gen/", "/quote-estimate-generator/", "/receipt-generator/" ], "answer": "Draft plain-language payment terms for invoices, quotes, retainers, deposits, late fees, and due dates.", "formula": "Composes a payment terms clause from structured inputs: deposit %, due window, late fee, payment methods, and scope of services. Output is a plain-text terms paragraph ready to paste into contracts or invoices.", "example": "A 25% deposit due before services begin, balance due within 14 days of invoice, with a reasonable late fee.", "assumptions": [ "The user sets terms they intend to enforce.", "The clause is a plain-English template.", "Local legal requirements are checked separately." ], "sources": [ { "organization": "Wikipedia", "title": "Invoice", "url": "https://en.wikipedia.org/wiki/Invoice" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What does the generator do?", "It composes a payment-terms clause from your deposit %, due window, late fee, accepted methods, and scope — ready to paste into invoices." ], [ "What are good payment terms?", "Common freelance terms: 25–50% deposit, balance due in 14 days, 1.5%/month late fee after a grace period." ], [ "Is this legally binding?", "The generated text is a template. Late-fee rules vary by jurisdiction — review with a lawyer for important contracts." ], [ "Why do I need written terms?", "Clear written terms prevent disputes and give you grounds to enforce payment." ], [ "Can I edit the output?", "Yes — treat it as a starting draft and adjust to your standard practice." ], [ "How do I enforce late fees?", "State them on every invoice, send reminders on day 1 of lateness, and apply them consistently." ], [ "What is a good deposit?", "25–50% for new clients, enough to cover initial work and discourage no-shows." ] ] }, { "slug": "payout-ratio-calculator", "name": "Payout Ratio Calculator", "canonical_url": "https://boringtoolskit.com/payout-ratio-calculator/", "category": "Finance & Investing", "description": "Payout ratio calculator: dividends as a share of earnings.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "paypal-fee-calculator", "name": "PayPal Fee Calculator", "canonical_url": "https://boringtoolskit.com/paypal-fee-calculator/", "category": "Everyday Calculators", "description": "Calculate estimated PayPal fees, net proceeds, or the amount to charge for a target net. Starts with an editable 3.49% + $0.49 planning preset.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/stripe-fee-calculator/", "/etsy-fee-profit/", "/sales-tax-vat-calculator/" ], "answer": "Calculate estimated PayPal fees, net proceeds, or the amount to charge for a target net. Starts with an editable 3.49% + $0.49 planning preset.", "formula": "Fee = amount × percentage rate + fixed fee. Net = amount − fee. Rates vary by transaction type (goods & services ~2.99% + $0.49 in the US).", "example": "A $100 goods-and-services payment: $100 × 2.99% + $0.49 = $3.48 in fees — net $96.52.", "assumptions": [ "The standard rate for the user's country applies.", "No currency conversion is involved.", "The transaction is goods & services." ], "sources": [ { "organization": "Wikipedia", "title": "PayPal", "url": "https://en.wikipedia.org/wiki/PayPal" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How much does PayPal charge?", "About 2.99% + $0.49 per US goods-and-services transaction — $3.48 on a $100 payment." ], [ "How do I calculate the fee?", "Amount × rate + fixed: $100 × 2.99% + $0.49 = $3.48." ], [ "Are friends-and-family payments free?", "Usually, in the same country — but sellers lose protection, so goods should go through goods & services." ], [ "Why is my rate different?", "Rates vary by country, currency, account type, and volume — check your merchant rate." ], [ "How do I price to cover fees?", "Divide your desired net by (1 − rate): $100 net at 2.99% needs about $103.09." ], [ "Do cross-border payments cost more?", "Yes — currency conversion and cross-border fees add a few percent." ], [ "How does this compare to Stripe?", "Stripe charges 2.9% + $0.30 (US) — slightly cheaper on most ticket sizes. Compare with your volume." ], [ "What is the PayPal fee?", "2.99% plus a fixed fee (about $0.49 for US domestic) on goods-and-services payments." ], [ "Who pays the fee?", "The recipient of a goods-and-services payment pays the merchant fee." ], [ "Are international payments more expensive?", "Yes — currency conversion (3–4%) and international rates raise the cost." ], [ "How do I net a specific amount?", "Divide the target by (1 − rate) and add the fixed fee share — the calculator does both directions." ] ] }, { "slug": "pdf-to-jpg", "name": "PDF to JPG Converter", "canonical_url": "https://boringtoolskit.com/pdf-to-jpg/", "category": "Converters", "description": "Convert PDF pages to images directly in your browser.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/image-resize/", "/base64-tool/", "/qr-generator/" ], "answer": "Convert PDF pages to images directly in your browser.", "formula": "Renders a chosen PDF page to a JPG image at a scale multiplier (1–6×). Higher scale means larger pixel dimensions; the page number selects which page is rendered. All processing happens locally in your browser.", "example": "Rendering page 1 of a PDF at 2× zoom produces a JPG with twice the pixel dimensions of a 1× render.", "assumptions": [ "The browser supports built-in PDF rendering.", "The user selects the correct page and scale.", "Output quality matches the source PDF's content." ], "sources": [ { "organization": "Wikipedia", "title": "Portable Document Format", "url": "https://en.wikipedia.org/wiki/Portable_Document_Format" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I convert a PDF page to JPG?", "Upload the PDF, pick the page and scale, and download the preview — the tool renders it locally in your browser." ], [ "Is my PDF uploaded anywhere?", "No — everything runs locally in your browser. Your document never leaves your device." ], [ "What does the scale setting do?", "It multiplies the output resolution. 1× is screen quality; 3×+ gives sharper, larger images for printing." ], [ "Can I convert multiple pages?", "Select one page at a time. For multi-page conversion, repeat per page or use a batch tool." ], [ "Why is the text no longer selectable?", "JPG is a flat image — the rendered page loses its text layer. Use PDF-to-text tools if you need the text." ], [ "What file sizes should I expect?", "Depends on scale and content: 1–2× is typically 100 KB–2 MB per page; higher scales grow quickly." ], [ "Why does my page look different from Acrobat?", "Browser PDF engines render fonts and complex layouts slightly differently than desktop software." ] ] }, { "slug": "pe-ratio-calculator", "name": "PE Ratio Calculator", "canonical_url": "https://boringtoolskit.com/pe-ratio-calculator/", "category": "Finance & Investing", "description": "PE ratio calculator: price-to-earnings from price and EPS.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "pension-calculator", "name": "Pension Calculator", "canonical_url": "https://boringtoolskit.com/pension-calculator/", "category": "Everyday Calculators", "description": "Estimate a monthly pension benefit from salary, years of service, and a multiplier.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/retirement-planning-calculator/", "/roth-ira-calculator/", "/annuity-calculator/" ], "answer": "Estimate a monthly pension benefit from salary, years of service, and a multiplier.", "formula": "Annual benefit = multiplier × years of service × final average salary. Monthly benefit = annual benefit ÷ 12; income replacement ratio = annual benefit ÷ salary × 100.", "example": "A $80,000 final average salary with 30 years of service and a 1.5% multiplier: annual pension = 0.015 × 30 × $80,000 = $36,000, or $3,000/month — replacing 45% of salary.", "assumptions": [ "The plan uses a straight multiplier × years × final salary formula.", "No early-retirement reduction or survivor election is applied.", "The entered multiplier matches your plan's benefit formula." ], "sources": [ { "organization": "Investopedia", "title": "Pension Plan", "url": "https://www.investopedia.com/terms/p/pensionplan.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a pension plan?", "A pension (defined-benefit) plan is an employer retirement plan that pays a formula-based monthly benefit for life, based on salary and years of service." ], [ "How is a pension calculated?", "Annual benefit = multiplier × years of service × final average salary. For example, 1.5% × 30 years × $80,000 = $36,000/year." ], [ "What is the multiplier?", "The percentage of salary credited per year of service (commonly 1–2%). Higher multipliers reward longer tenure." ], [ "What is final average salary?", "Usually your average salary over your highest-paid 3–5 years. Using the highest years raises the benefit." ], [ "Can I collect before normal retirement age?", "Often yes, but with a permanent reduction — the benefit is cut by a percentage for each year you retire early." ], [ "Is my pension guaranteed?", "Not absolutely. Private plans are insured by the PBGC up to limits; public plans depend on funding. Plans can also be frozen, reducing future accruals." ], [ "How does a pension compare to a 401(k)?", "A pension pays a defined monthly benefit with employer risk; a 401(k) is a defined-contribution account whose value depends on contributions and investment returns. Many workers now have both." ] ] }, { "slug": "percent-difference-calculator", "name": "Percent Difference Calculator", "canonical_url": "https://boringtoolskit.com/percent-difference-calculator/", "category": "Everyday Calculators", "description": "Percent difference calculator: relative difference between two values.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-27", "related_urls": [], "answer": "Percent difference calculator: relative difference between two values.", "formula": "Percent difference = |a − b| ÷ ((a + b)/2) × 100.", "example": "Between 80 and 100: 20 ÷ 90 × 100 ≈ 22.2%.", "assumptions": [ "Standard geometric or arithmetic definitions apply.", "Inputs use the units you choose.", "Results are estimates, not professional advice." ], "sources": [ { "organization": "Standard mathematics definitions", "title": "Arithmetic and geometry formulas", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "percent-solution-calculator", "name": "Percent Solution Calculator", "canonical_url": "https://boringtoolskit.com/percent-solution-calculator/", "category": "Chemistry", "description": "Calculate percent solution concentration by weight or volume.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/molarity-calculator/", "/molarity-from-mass-calculator/", "/ph-calculator/" ], "answer": "Calculate percent solution concentration by weight or volume.", "formula": "Percent w/v = (solute mass ÷ solution volume in mL) × 100. Percent w/w = (solute mass ÷ solution mass) × 100.", "example": "5 g of solute in 200 mL of solution = 5 ÷ 200 × 100 = 2.5% w/v. The same in 200 g of solution = 2.5% w/w.", "assumptions": [ "w/v uses solution volume (mL); w/w uses total solution mass (g).", "Total mass or volume must be positive.", "The percent basis (w/v vs w/w) changes the meaning of the concentration." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "percent-yield-calculator", "name": "Percent Yield Calculator", "canonical_url": "https://boringtoolskit.com/percent-yield-calculator/", "category": "Chemistry", "description": "Calculate percent yield from actual and theoretical yield.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/limiting-reagent-calculator/", "/stoichiometry-calculator/", "/empirical-formula-calculator/" ], "answer": "Calculate percent yield from actual and theoretical yield.", "formula": "Percent yield = (actual yield ÷ theoretical yield) × 100.", "example": "A reaction that gives 8.5 g actually and has a theoretical yield of 10.0 g: percent yield = 8.5 ÷ 10.0 × 100 = 85%.", "assumptions": [ "Actual and theoretical yield are in the same units.", "Theoretical yield must be positive.", "A yield above 100% indicates impurities or measurement error, not a real excess." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "percentage-calc", "name": "Percentage Calculator", "canonical_url": "https://boringtoolskit.com/percentage-calc/", "category": "Finance & Investing", "description": "Calculate percentages, increases, and changes instantly.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/gpa-calculator/", "/grade-calculator/", "/simple-interest-calculator/" ], "answer": "Calculate percentages, increases, and changes instantly.", "formula": "Three modes: (1) X% of Y = X ÷ 100 × Y; (2) X as a percent of Y = X ÷ Y × 100; (3) percent change = (new − old) ÷ old × 100.", "example": "15% of 200 = 30. 25 is 31.25% of 80. A price rising from $50 to $75 is a 50% increase.", "assumptions": [ "The selected mode matches the question.", "Values are non-negative except where change allows negatives.", "Relative change is measured from the old value." ], "sources": [ { "organization": "Wikipedia", "title": "Percentage", "url": "https://en.wikipedia.org/wiki/Percentage" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate X% of Y?", "Multiply: X ÷ 100 × Y. 15% of 200 = 0.15 × 200 = 30." ], [ "How do I find what percent X is of Y?", "Divide: X ÷ Y × 100. 25 ÷ 80 × 100 = 31.25%." ], [ "How do I calculate percent change?", "(New − old) ÷ old × 100. $50 to $75 = (25 ÷ 50) × 100 = 50% increase." ], [ "What's the difference between percent and percentage points?", "A rate going from 5% to 7% is a 2-percentage-point rise but a 40% relative increase. They measure different things." ], [ "Why doesn't a 50% rise then fall return to the original?", "Because the fall is relative to the larger value: 100 → 150 → 75. Percentage changes don't cancel symmetrically." ], [ "How do I calculate a tip?", "Use 'of': 18% of the bill. On a $40 bill that's $7.20." ], [ "How do I calculate a discount?", "Subtract X% of the price from the price — or multiply by (1 − X/100)." ] ] }, { "slug": "percentage-change-calculator", "name": "Percentage Change Calculator", "canonical_url": "https://boringtoolskit.com/percentage-change-calculator/", "category": "Everyday Calculators", "description": "Percentage change calculator: the % increase or decrease between two values.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-27", "related_urls": [], "answer": "Percentage change calculator: the % increase or decrease between two values.", "formula": "Percent change = (new − old) ÷ |old| × 100.", "example": "50 → 65 is a +30% change; 65 → 50 is a −23.1% change.", "assumptions": [ "Standard geometric or arithmetic definitions apply.", "Inputs use the units you choose.", "Results are estimates, not professional advice." ], "sources": [ { "organization": "Standard mathematics definitions", "title": "Arithmetic and geometry formulas", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "percentage-error-calculator", "name": "Percentage Error Calculator", "canonical_url": "https://boringtoolskit.com/percentage-error-calculator/", "category": "Statistics", "description": "Percentage error calculator: measured vs true value as a percentage, for labs and measurements.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "percentage-markup-calculator", "name": "Percentage Markup Calculator", "canonical_url": "https://boringtoolskit.com/percentage-markup-calculator/", "category": "Everyday Calculators", "description": "Enter a cost and markup percentage to get the selling price, markup amount, and profit margin. What is a 15% markup on $85? It is $97.75.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/profit-margin-markup-calculator/", "/price-increase-impact-calculator/", "/percentage-calc/" ], "answer": "Enter a cost and markup percentage to get the selling price, markup amount, and profit margin. What is a 15% markup on $85? It is $97.75.", "formula": "Markup = (selling price − cost) ÷ cost × 100. Margin = (selling price − cost) ÷ selling price × 100. The tool converts between the two.", "example": "An item costing $80 sold at $100: markup = 25%, margin = 20%.", "assumptions": [ "Cost is the total product cost.", "Selling price is before tax and discounts.", "The conversion follows standard formulas." ], "sources": [ { "organization": "Wikipedia", "title": "Markup (business)", "url": "https://en.wikipedia.org/wiki/Markup_(business)" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What's the difference between markup and margin?", "Markup is profit ÷ cost; margin is profit ÷ price. $80 cost at $100 sale = 25% markup, 20% margin." ], [ "How do I convert markup to margin?", "Margin = markup ÷ (1 + markup): 25% markup → 20% margin." ], [ "How do I convert margin to markup?", "Markup = margin ÷ (1 − margin): 20% margin → 25% markup." ], [ "Why do people confuse them?", "Both are 'percentages of profit' — but on different bases (cost vs price). The difference grows with the percentage." ], [ "How do I price for a target margin?", "Price = cost ÷ (1 − margin): $80 ÷ 0.80 = $100 for a 20% margin." ], [ "Which should I track?", "Margin for business health (it's the share of revenue you keep); markup for pricing from cost." ], [ "Do discounts affect this?", "Yes — a discount comes out of the price, so it reduces margin dollar-for-dollar." ], [ "How do I calculate markup?", "Profit ÷ cost × 100: $10 profit on $25 cost = 40%." ], [ "What is the difference between markup and margin?", "Markup divides by cost; margin divides by price." ], [ "How do I price from markup?", "Cost × (1 + markup): $25 × 1.4 = $35." ], [ "Do markups stack?", "Yes — each channel layer multiplies the previous price." ] ] }, { "slug": "percentile-calculator", "name": "Percentile Calculator", "canonical_url": "https://boringtoolskit.com/percentile-calculator/", "category": "Everyday Calculators", "description": "Find the value at any percentile in a data set, or the percentile rank of a given value. Enter your data and the percentile you need.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/quartile-calculator/", "/statistics-calculator/", "/z-score-calculator/" ], "answer": "Find the value at any percentile in a data set, or the percentile rank of a given value. Enter your data and the percentile you need.", "formula": "The pth percentile is the value at rank ceil((p ÷ 100) × n), clamped between 1 and n, of the sorted data set.", "example": "For data 10, 20, 30, 40, 50 (n = 5), the 60th percentile rank = ceil(0.60 × 5) = 3, so the 60th percentile is 30.", "assumptions": [ "The percentile value must be between 1 and 99.", "The tool uses the nearest-rank method on the sorted data.", "At least one data point is required." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "NIST/SEMATECH e-Handbook of Statistical Methods", "url": "https://www.itl.nist.gov/div898/handbook/" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "period-cycle-calculator", "name": "Period Cycle Calculator", "canonical_url": "https://boringtoolskit.com/period-cycle-calculator/", "category": "Health", "description": "Period cycle calculator: estimate the next period and fertile window from cycle length.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "permutation-combination-calculator", "name": "Permutation Combination Calculator", "canonical_url": "https://boringtoolskit.com/permutation-combination-calculator/", "category": "Statistics", "description": "Permutation and combination calculator: nPr and nCr.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "permutations-calculator", "name": "Permutations Calculator (nPr)", "canonical_url": "https://boringtoolskit.com/permutations-calculator/", "category": "Everyday Calculators", "description": "Calculate the number of permutations (nPr) of arranging r items from n, with the formula explained.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "August 2026", "related_urls": [ "/combinations-calculator/", "/order-of-operations-calculator/", "/general-scientific-calculator/" ], "answer": "Calculate the number of permutations (nPr) of arranging r items from n, with the formula explained.", "formula": "nPr = n! ÷ (n − r)! = n × (n − 1) × … × (n − r + 1). The calculator multiplies consecutive terms and guards against overflow.", "example": "10 arrange 3 = 720 distinct ordered arrangements of 3 items from 10.", "assumptions": [ "r must be between 0 and n, and n at least 1.", "Order matters (ordered arrangement).", "Result is an integer; overflow is reported as an invalid input." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculation methodology and verification standard", "url": "/methodology/" } ], "faqs": [ [ "What is a permutation (nPr)?", "A permutation counts the number of ways to arrange r items taken from n where order matters. It is written nPr." ], [ "What is the permutation formula?", "nPr = n! ÷ (n − r)!, which simplifies to n × (n − 1) × … × (n − r + 1)." ], [ "How is a permutation different from a combination?", "Permutations count order as significant (arranging), while combinations do not (selecting a set)." ] ] }, { "slug": "personal-loan-calculator", "name": "Personal Loan Calculator", "canonical_url": "https://boringtoolskit.com/personal-loan-calculator/", "category": "Finance & Investing", "description": "Personal loan calculator: monthly payment with origination fee.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "pet-annual-cost-calculator", "name": "Pet Annual Cost Calculator", "canonical_url": "https://boringtoolskit.com/pet-annual-cost-calculator/", "category": "Pets", "description": "Pet annual cost calculator: yearly dog or cat expenses.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "ph-calculator", "name": "pH Calculator", "canonical_url": "https://boringtoolskit.com/ph-calculator/", "category": "Chemistry", "description": "Calculate pH, pOH, and hydrogen/hydroxide ion concentration for acids and bases.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/molarity-calculator/", "/molarity-from-mass-calculator/", "/percent-solution-calculator/" ], "answer": "Calculate pH, pOH, and hydrogen/hydroxide ion concentration for acids and bases.", "formula": "pH = −log₁₀[H⁺]. pOH = 14 − pH. [OH⁻] = 10^(−pOH).", "example": "A solution with [H⁺] = 0.001 mol/L has pH = −log₁₀(0.001) = 3.00, which is acidic; pOH = 11.00.", "assumptions": [ "Hydrogen ion concentration is entered in mol/L.", "The calculation assumes aqueous solution at 25°C.", "A pH of 7 is neutral, below 7 acidic, above 7 basic." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "pipe-sizing-calculator", "name": "Pipe Sizing Calculator", "canonical_url": "https://boringtoolskit.com/pipe-sizing-calculator/", "category": "Construction & Measurement", "description": "Pipe sizing calculator: minimum pipe diameter for a target flow rate and velocity.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "pipe-volume-calculator", "name": "Pipe Volume Calculator", "canonical_url": "https://boringtoolskit.com/pipe-volume-calculator/", "category": "Construction & Measurement", "description": "Pipe volume calculator: volume of water in a pipe from diameter and length.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "pizza-dough-calculator", "name": "Pizza Dough Calculator", "canonical_url": "https://boringtoolskit.com/pizza-dough-calculator/", "category": "Food & Cooking", "description": "Pizza dough calculator: flour, water, salt, yeast by baker's percentage.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "planetary-weight-calculator", "name": "Planetary Weight Calculator", "canonical_url": "https://boringtoolskit.com/planetary-weight-calculator/", "category": "Astronomy", "description": "Planetary weight calculator: your weight on other planets and moons from surface gravity ratios.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "plank-test-calculator", "name": "Plank Test Calculator", "canonical_url": "https://boringtoolskit.com/plank-test-calculator/", "category": "Sports", "description": "Plank test calculator: core endurance rating from hold time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "poisson-probability-calculator", "name": "Poisson Probability Calculator", "canonical_url": "https://boringtoolskit.com/poisson-probability-calculator/", "category": "Statistics", "description": "Poisson probability calculator: probability of exactly k events given a mean rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "pollen-forecast-calculator", "name": "Pollen Forecast Calculator", "canonical_url": "https://boringtoolskit.com/pollen-forecast-calculator/", "category": "Health", "description": "Pollen forecast calculator: current pollen levels for any city.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "polynomial-evaluator", "name": "Polynomial Evaluator", "canonical_url": "https://boringtoolskit.com/polynomial-evaluator/", "category": "Everyday Calculators", "description": "Polynomial evaluator: evaluate ax² + bx + c at x.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "pomodoro-timer", "name": "Pomodoro Timer", "canonical_url": "https://boringtoolskit.com/pomodoro-timer/", "category": "Time & Work", "description": "Focus with work and break intervals — set focus minutes, short and long breaks, and run the Pomodoro timer in your browser. Free, no signup.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/countdown-timer/", "/stopwatch/", "/word-counter/" ], "answer": "Focus with work and break intervals — set focus minutes, short and long breaks, and run the Pomodoro timer in your browser. Free, no signup.", "formula": "Work in 25-minute focus blocks separated by 5-minute breaks; after 4 blocks, take a longer break (15–30 minutes). Cycles are configurable in the tool.", "example": "Four 25-minute focus sessions with 5-minute breaks = 2 hours of deep work, then a 15-minute long break.", "assumptions": [ "The user works on one task per focus block.", "Breaks are taken away from the screen.", "Block lengths are adjustable to the task." ], "sources": [ { "organization": "Wikipedia", "title": "Pomodoro Technique", "url": "https://en.wikipedia.org/wiki/Pomodoro_Technique" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is the Pomodoro Technique?", "A time-management method: 25-minute focus blocks separated by 5-minute breaks, with a longer break after four blocks." ], [ "How long should focus blocks be?", "25 minutes is the classic length, but 50–90 minutes suits deep work like coding or writing. Adjust to your attention span." ], [ "Why does it work?", "It converts overwhelming work into a single timed block, and the breaks prevent burnout — reducing procrastination and sustaining focus." ], [ "What do I do during breaks?", "Step away from the screen: stretch, walk, hydrate. The break is the recovery that makes the next block productive." ], [ "How many pomodoros should I do per day?", "8–12 is a common range for full workdays, but quality matters more than count — stop when focus genuinely drops." ], [ "What if I get interrupted?", "Note the interruption and return to the block; if it's urgent, end the block and start a new one after handling it." ], [ "Can I adjust the timer?", "Yes — the tool lets you set focus, short break, and long break minutes to fit your workflow." ] ] }, { "slug": "pond-volume-calculator", "name": "Pond Volume Calculator", "canonical_url": "https://boringtoolskit.com/pond-volume-calculator/", "category": "Construction & Measurement", "description": "Pond volume calculator: gallons in a rectangular pond.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "pool-volume-calculator", "name": "Pool Volume Calculator", "canonical_url": "https://boringtoolskit.com/pool-volume-calculator/", "category": "Construction & Measurement", "description": "Pool volume calculator: gallons in a rectangular, round, or oval pool.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "population-density-calculator", "name": "Population Density Calculator", "canonical_url": "https://boringtoolskit.com/population-density-calculator/", "category": "Geography", "description": "Population density calculator: people per square kilometer or mile from population and area.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "portion-size-calculator", "name": "Portion Size Calculator", "canonical_url": "https://boringtoolskit.com/portion-size-calculator/", "category": "Food & Cooking", "description": "Portion size calculator: scale a recipe's serving size to a new number of portions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "poshmark-fee-calculator", "name": "Poshmark Fee Calculator", "canonical_url": "https://boringtoolskit.com/poshmark-fee-calculator/", "category": "Seller & Business", "description": "Poshmark fee calculator: selling fees and net for any sale price.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "post-frequency-calculator", "name": "Post Frequency Calculator", "canonical_url": "https://boringtoolskit.com/post-frequency-calculator/", "category": "Social Media", "description": "Plan a sustainable social posting cadence across platforms.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/follower-growth-calculator/", "/engagement-rate-calculator/", "/video-watch-time-calculator/" ], "answer": "Plan a sustainable social posting cadence across platforms.", "formula": "Total posts = posts per week × weeks. Estimated reach = total posts × average views per post. Monthly views ≈ posts/week × 4.333 × avg views.", "example": "5 posts/week for 8 weeks at 1,200 views each: 40 posts, ~48,000 total views, ~26,000/month.", "assumptions": [ "Posts per week, average views, and weeks are the user's estimates.", "Views per post are assumed stable across the period.", "The metric is a reach proxy; it does not measure followers, subscriptions, or engagement." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "potential-energy-calculator", "name": "Potential Energy Calculator", "canonical_url": "https://boringtoolskit.com/potential-energy-calculator/", "category": "Physics", "description": "Calculate gravitational potential energy from mass, height, and gravity (PE = mgh).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/kinetic-energy-calculator/", "/force-calculator/", "/work-power-calculator/" ], "answer": "Calculate gravitational potential energy from mass, height, and gravity (PE = mgh).", "formula": "Gravitational potential energy (PE) = mass × height × gravity. Gravity defaults to 9.81 m/s². Units: joules (J).", "example": "A 5 kg object at 10 m high (g = 9.81): PE = 5 × 10 × 9.81 = 490.5 J.", "assumptions": [ "Mass is in kilograms and height in meters.", "Gravity defaults to Earth's 9.81 m/s² and is editable.", "The reference height is the ground level (PE = 0 at the reference floor)." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "power-factor-calculator", "name": "Power Factor Calculator", "canonical_url": "https://boringtoolskit.com/power-factor-calculator/", "category": "Energy & Electrical", "description": "Power factor calculator: PF from real watts and apparent volt-amps.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "pregnancy-calculator", "name": "Pregnancy Calculator", "canonical_url": "https://boringtoolskit.com/pregnancy-calculator/", "category": "Health", "description": "Estimate your pregnancy due date and current week from your last period, conception date, or a known due date. Private, no account.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/due-date-calculator/", "/ovulation-calculator/", "/ideal-weight-calculator/" ], "answer": "Estimate your pregnancy due date and current week from your last period, conception date, or a known due date. Private, no account.", "formula": "Due date = LMP + 280 days (40 weeks). Key milestones: conception ≈ LMP + 14 days; the estimate tracks weeks of pregnancy from the LMP and flags the current trimester (first: 0–13 weeks, second: 14–27, third: 28+).", "example": "With an LMP of February 1, 2026: due date ≈ November 8, 2026 — 40 weeks later. Conception was around mid-February.", "assumptions": [ "A regular 28-day cycle with ovulation at day 14.", "A single pregnancy.", "The entered LMP is accurate." ], "sources": [ { "organization": "ACOG", "title": "Methods for Estimating the Due Date", "url": "https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2017/05/methods-for-estimating-the-due-date" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How is my due date calculated?", "Add 280 days (40 weeks) to the first day of your last menstrual period. The tool also estimates conception and your current week." ], [ "What week am I in?", "Count from the LMP: today minus the LMP in weeks. The tool does this and flags the trimester." ], [ "When does the third trimester start?", "At 28 weeks. The first trimester is 0–13 weeks, the second 14–27, the third 28+." ], [ "Why is pregnancy 40 weeks when it feels shorter?", "Dating starts at the LMP, about two weeks before conception — so the baby is roughly 38 weeks from conception at the 40-week mark." ], [ "How accurate is the due date?", "Only about 5% of babies arrive exactly on it. Full-term delivery ranges from about 37 to 42 weeks." ], [ "Will my provider change the date?", "Possibly — an early ultrasound in the first trimester is the most accurate dating method and may adjust the LMP-based estimate." ], [ "Do multiples have different milestones?", "The dating is the same, but twins and higher-order multiples are usually delivered earlier, often planned for 37–38 weeks." ] ] }, { "slug": "pregnancy-due-date-calculator", "name": "Pregnancy Due Date Calculator", "canonical_url": "https://boringtoolskit.com/pregnancy-due-date-calculator/", "category": "Health", "description": "Pregnancy due date calculator: estimate the due date from the first day of the last menstrual period.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "pregnancy-weight-gain-calculator", "name": "Pregnancy Weight Gain Calculator", "canonical_url": "https://boringtoolskit.com/pregnancy-weight-gain-calculator/", "category": "Health", "description": "Pregnancy weight gain calculator: IOM recommended ranges by BMI and week.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "present-value-calculator", "name": "Present Value Calculator", "canonical_url": "https://boringtoolskit.com/present-value-calculator/", "category": "Everyday Calculators", "description": "Find what a future lump sum is worth today at a given discount rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/future-value-calculator/", "/compound-interest/", "/annuity-calculator/" ], "answer": "Find what a future lump sum is worth today at a given discount rate.", "formula": "Present value = future amount ÷ (1 + discount rate ÷ compounds)^(compounds × years). The discount is the difference between the future amount and its present value.", "example": "A $100,000 payment due in 10 years at a 6% discount rate compounded annually: PV = $100,000 ÷ 1.06^10 ≈ $55,839.48, so the discount is about $44,160.52.", "assumptions": [ "A constant discount rate over the full period.", "Compounding at the selected frequency.", "No taxes, inflation adjustments, or risk premiums beyond the chosen rate." ], "sources": [ { "organization": "Investopedia", "title": "Present Value (PV)", "url": "https://www.investopedia.com/terms/p/presentvalue.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is present value?", "The current worth of a future sum of money, found by discounting it at a rate that reflects the time value of money and opportunity cost." ], [ "Why is a dollar today worth more than a dollar later?", "Because today's dollar can be invested and grow. Discounting accounts for that lost growth plus inflation and risk." ], [ "How do I choose a discount rate?", "Use your opportunity cost — the return you could earn elsewhere (e.g., a safe investment rate, or your required return for riskier projects). A higher rate produces a lower present value." ], [ "What is the difference between present and future value?", "Future value grows a present amount forward with compounding; present value discounts a future amount backward. They are inverses of each other." ], [ "How does compounding frequency affect the result?", "More frequent compounding (monthly vs annual) increases the effective discount, lowering the present value slightly." ], [ "What is this used for?", "Valuing investments, comparing lump sums vs payment streams, pricing bonds, and discounted cash flow (DCF) analysis." ], [ "Does present value account for inflation?", "Only if your discount rate is a real (inflation-adjusted) rate. A nominal rate leaves inflation embedded in the number." ] ] }, { "slug": "pressure-calculator", "name": "Pressure Calculator", "canonical_url": "https://boringtoolskit.com/pressure-calculator/", "category": "Physics", "description": "Calculate pressure from force and area (P = F/A) with pascal and psi results.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/force-calculator/", "/density-calculator/", "/wave-calculator/" ], "answer": "Calculate pressure from force and area (P = F/A) with pascal and psi results.", "formula": "Pressure (P) = force ÷ area. Units: pascals (Pa) = N/m². Conversions: kPa = Pa ÷ 1000; psi = Pa × 0.000145038.", "example": "A 500 N force on an area of 2 m²: P = 500 ÷ 2 = 250 Pa = 0.25 kPa = 0.036 psi.", "assumptions": [ "Force is in newtons and area in square meters.", "Pressure is assumed evenly distributed over the area.", "Positive values are required for both inputs." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "pressure-converter", "name": "Pressure Converter", "canonical_url": "https://boringtoolskit.com/pressure-converter/", "category": "Converters", "description": "Pressure converter: psi, bar, kPa, atm.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "pressure-cooker-time-calculator", "name": "Pressure Cooker Time Calculator", "canonical_url": "https://boringtoolskit.com/pressure-cooker-time-calculator/", "category": "Food & Cooking", "description": "Pressure cooker time calculator: cooking times for common foods.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "price-increase-impact-calculator", "name": "Price Increase Impact Calculator", "canonical_url": "https://boringtoolskit.com/price-increase-impact-calculator/", "category": "Seller & Business", "description": "Compare revenue and contribution after a price change and expected unit-volume response.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/break-even-units-calculator/", "/cash-flow-runway-calculator/", "/customer-lifetime-value-calculator/" ], "answer": "Compare revenue and contribution after a price change and expected unit-volume response.", "formula": "New volume = current units × (1 + volume change %). Current contribution = (current price − variable cost) × current units. New contribution = (new price − variable cost) × new volume. The tool compares revenue and profit impact.", "example": "Raising price from $50 to $55 with a 5% volume drop: units 1,000 → 950, contribution (at $30 variable cost) rises from $20,000 to $23,750 — an 18.8% profit gain despite fewer sales.", "assumptions": [ "Variable cost per unit is constant.", "Fixed costs don't change with volume in the modeled range.", "The volume change estimate is realistic." ], "sources": [ { "organization": "Wikipedia", "title": "Price elasticity of demand", "url": "https://en.wikipedia.org/wiki/Price_elasticity_of_demand" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How does a price increase affect profit?", "It raises margin per unit but may cut volume. The calculator compares both: (price − cost) × units before and after." ], [ "What is price elasticity?", "How much demand responds to price — how many sales you lose per percent of price increase. Elastic products lose more volume." ], [ "Why do small price increases help so much?", "Because variable cost is fixed, nearly the entire increase flows to profit. At 30% margins, a 1% price rise can lift profit ~10% if volume holds." ], [ "How much volume can I afford to lose?", "The tool shows the trade-off directly: raise price from $50 to $55, and you can lose up to ~15% volume and still break even on contribution." ], [ "What if my costs change too?", "Enter the new variable cost with the new price — the tool uses what you input." ], [ "How do I test a price increase?", "Raise prices on a small segment or channel first, measure the volume change, then decide." ], [ "Is the volume estimate reliable?", "No — it's your best guess. Run scenarios (pessimistic, realistic, optimistic) to see the range." ], [ "What is the volume trade-off?", "Some customers leave; the calculator shows the break-even volume drop." ], [ "How is the break-even found?", "The volume change where the price gain equals the lost contribution — the calculator's reverse view." ], [ "Should I raise prices?", "If the modeled profit gain exceeds the volume risk — the calculator quantifies both." ] ] }, { "slug": "price-per-square-foot", "name": "Price Per Square Foot Calculator", "canonical_url": "https://boringtoolskit.com/price-per-square-foot/", "category": "Everyday Calculators", "description": "Work out price per square foot, or back into total price or area from a rate and budget.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/market-value-calculator/", "/property-area-calculator/", "/square-footage-calculator/" ], "answer": "Work out price per square foot, or back into total price or area from a rate and budget.", "formula": "Price per sq ft = price ÷ area. The tool also works backward: total price = area × rate.", "example": "$400,000 on 2,000 sq ft: $200 per square foot.", "assumptions": [ "The area is the living area (not lot).", "Comparisons use similar property types.", "The rate reflects the local market." ], "sources": [ { "organization": "Wikipedia", "title": "Price per square foot", "url": "https://en.wikipedia.org/wiki/Price_per_square_foot" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate price per square foot?", "Divide the price by the area: $400,000 ÷ 2,000 = $200/sq ft." ], [ "How do I estimate a home's value from the rate?", "Multiply the area by the local rate: 2,000 × $200 = $400,000." ], [ "What is a typical $/sq ft?", "It varies wildly — $100–150 in many US metros, $500+ in premium coastal areas." ], [ "Does lot size count?", "No — the standard uses living area. Land value distorts per-sq-ft comparisons on big lots." ], [ "Why do two similar homes differ per foot?", "Location, condition, finishes, and layout efficiency all shift the rate." ], [ "Can I use it for rentals?", "Rent per sq ft is the same concept for comparing rental rates." ], [ "Is this the same as the market value calculator?", "Similar — this converts price/area/rate; the market value calculator adds quality and condition factors." ], [ "Is it a good comparison metric?", "Useful within a market and home type; weak across neighborhoods and classes." ], [ "What does a renovation cost per square foot?", "$150–$300+ depending on scope and finishes." ], [ "Can I price from $/sq ft?", "Yes — rate × area gives the estimate." ] ] }, { "slug": "price-to-rent-ratio-calculator", "name": "Price-to-Rent Ratio Calculator", "canonical_url": "https://boringtoolskit.com/price-to-rent-ratio-calculator/", "category": "Finance & Investing", "description": "Calculate the price-to-rent ratio. Enter home price and annual rent to see the classic buy-vs-rent market signal.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/rental-yield-calculator/", "/gross-rent-multiplier-calculator/", "/rent-to-value-calculator/" ], "answer": "Calculate the price-to-rent ratio. Enter home price and annual rent to see the classic buy-vs-rent market signal.", "formula": "Price-to-rent ratio = property price ÷ annual rent. Annual rent is monthly rent × 12. The ratio tells you whether buying or renting is the better financial move in a market.", "example": "A $300,000 home renting for $2,000/month ($24,000/year) has a price-to-rent ratio of $300,000 ÷ $24,000 = 12.5.", "assumptions": [ "Annual rent is monthly rent × 12.", "The ratio is a market comparison, not a per-property buy decision.", "Value and rent are the only inputs — investing costs are not modeled." ], "sources": [ { "organization": "Investopedia", "title": "Price-to-Rent Ratio", "url": "https://www.investopedia.com/terms/p/price-to-rent-ratio.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a good price-to-rent ratio?", "A general guide: under 15 leans toward buying, 16–20 is a gray zone, and over 20 leans toward renting. Markets vary." ], [ "How do I calculate price-to-rent?", "Price-to-rent = property price ÷ annual rent (monthly rent × 12)." ], [ "What does a ratio below 15 mean?", "Buying is often more cost-effective than renting in that market, because the purchase price is low relative to rent." ], [ "What does a ratio above 20 mean?", "Renting is usually the better financial choice — the purchase price is high relative to what the home rents for." ], [ "Does this account for interest rates?", "No. It's a simple historical gauge. Run a detailed model with your down payment and mortgage rate for your specific decision." ], [ "Is this about my own home or an investment?", "Both. It helps you decide whether to buy vs rent your residence, and also signals whether a market is over- or under-valued for landlords." ], [ "Why do analysts use this?", "It's a quick, comparable, price-relative-to-rent affordability signal, similar to a P/E ratio for housing." ] ] }, { "slug": "prime-checker", "name": "Prime Checker", "canonical_url": "https://boringtoolskit.com/prime-checker/", "category": "Everyday Calculators", "description": "Prime checker: is a number prime, with factors.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "prime-factorization-calculator", "name": "Prime Factorization Calculator", "canonical_url": "https://boringtoolskit.com/prime-factorization-calculator/", "category": "School & Education", "description": "Prime factorization calculator: prime factors with exponents for any number.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "print-size-calculator", "name": "Print Size Calculator", "canonical_url": "https://boringtoolskit.com/print-size-calculator/", "category": "Photo & Video", "description": "Print size calculator: compute print dimensions and PPI from pixel dimensions and physical print size.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "printable-calendar", "name": "Printable Calendar", "canonical_url": "https://boringtoolskit.com/printable-calendar/", "category": "Time & Work", "description": "Create a clean six-week monthly calendar with Sunday or Monday week starts, then print it or save it as a PDF.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/world-clock/", "/date-difference-calculator/", "/business-days-calculator/" ], "answer": "Create a clean six-week monthly calendar with Sunday or Monday week starts, then print it or save it as a PDF.", "formula": "Generates a month grid calendar for any year/month with correct weekday alignment, ready to print or save.", "example": "Selecting March 2026 produces a March grid with the 1st on the correct weekday and 31 days.", "assumptions": [ "The Gregorian calendar applies.", "Weeks start on Sunday by default.", "No holidays are pre-filled." ], "sources": [ { "organization": "Wikipedia", "title": "Calendar", "url": "https://en.wikipedia.org/wiki/Calendar" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I generate a printable calendar?", "Pick the year and month — the tool lays out the grid with correct weekday alignment for printing." ], [ "Can I print any month?", "Yes — any year and month in the Gregorian calendar." ], [ "Does it include holidays?", "No — it's a blank grid; add holidays by hand." ], [ "Does the week start on Sunday?", "By default, yes — common in the US; some regions start Monday." ], [ "Can I save it as a file?", "Use your browser's print-to-PDF to save the generated grid." ], [ "What is this used for?", "Classrooms, meal planning, habit tracking, and wall planning." ], [ "Does it handle leap years?", "Yes — February aligns correctly in leap years." ] ] }, { "slug": "prize-wheel", "name": "Prize Wheel Spinner", "canonical_url": "https://boringtoolskit.com/prize-wheel/", "category": "Everyday Calculators", "description": "Spin a prize wheel to randomly choose a winner from segments you add. Local browser randomness, no upload.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/random-number-generator/", "/random-name-picker/", "/coin-flip/" ], "answer": "Spin a prize wheel to randomly choose a winner from segments you add. Local browser randomness, no upload.", "formula": "Spins a segmented wheel with a physics-based decelerating rotation and unbiased random landing. Each segment's win probability equals its share of the wheel.", "example": "An 8-segment wheel gives each segment a 12.5% chance of landing on the pointer.", "assumptions": [ "Segments are equally weighted by default.", "The RNG is unbiased for practical purposes.", "Each spin is independent." ], "sources": [ { "organization": "Wikipedia", "title": "Random number generation", "url": "https://en.wikipedia.org/wiki/Random_number_generation" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How does the prize wheel work?", "It spins with deceleration and lands on a randomly selected segment — odds equal each segment's share of the wheel." ], [ "Can I customize the segments?", "Yes — add your own labels for prizes, names, or options." ], [ "Is the spin fair?", "Each segment's win probability equals its arc share, using a strong random source." ], [ "What is this used for?", "Giveaways, spin-to-win promotions, classroom picks, and decisions." ], [ "Can I weight segments?", "Odds follow segment size — make a segment bigger for higher odds." ], [ "Is the result legally binding?", "For meaningful draws, use a certified process — this is for practical use." ], [ "Can I reuse it?", "Yes — every spin is independent; re-spin as often as you like." ] ] }, { "slug": "product-description-generator", "name": "Product Description Generator", "canonical_url": "https://boringtoolskit.com/product-description-generator/", "category": "Generators", "description": "Generate a ready-to-use product description from your product, benefit, feature, and audience.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "August 2026", "related_urls": [ "/slogan-generator/", "/business-name-generator/", "/pdf-to-jpg/" ], "answer": "Generate a ready-to-use product description from your product, benefit, feature, and audience.", "formula": "The description is assembled from tone-specific templates that insert your product, benefit, feature, and audience, then appends a short benefit bullet list.", "example": "Enter a ceramic mug with 'keeps your coffee hot' to get a friendly product description.", "assumptions": [ "Generated output is a starting point, not final professional copy.", "Nothing you type leaves your browser.", "Results vary on each run because selection is random." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculation methodology and verification standard", "url": "/methodology/" } ], "faqs": [ [ "Is this real copy?", "It's a template filled with your inputs. Use it as a draft and edit it to match your brand voice." ], [ "Can I change the tone?", "Yes — choose Professional, Friendly, or Energetic." ], [ "Does it send my product to a model?", "No. The description is assembled from templates on your device." ] ] }, { "slug": "profit-margin-markup-calculator", "name": "Profit Margin and Markup Calculator", "canonical_url": "https://boringtoolskit.com/profit-margin-markup-calculator/", "category": "Seller & Business", "description": "Calculate profit, profit margin, markup on cost, and the selling price needed for a target margin from your cost and price.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/percentage-markup-calculator/", "/price-increase-impact-calculator/", "/break-even-units-calculator/" ], "answer": "Calculate profit, profit margin, markup on cost, and the selling price needed for a target margin from your cost and price.", "formula": "Margin = (price − cost) ÷ price × 100. Markup = (price − cost) ÷ cost × 100. The tool reports both from cost and price.", "example": "An item costing $80 sold at $100: 20% margin and 25% markup.", "assumptions": [ "Cost is the per-unit total cost.", "Price is before tax and discounts.", "Overhead is handled separately." ], "sources": [ { "organization": "Wikipedia", "title": "Profit margin", "url": "https://en.wikipedia.org/wiki/Profit_margin" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What's the difference between margin and markup?", "Margin is profit ÷ price; markup is profit ÷ cost. $80 cost at $100 sale = 20% margin, 25% markup." ], [ "How do I calculate profit margin?", "(Price − cost) ÷ price × 100: $20 ÷ $100 = 20%." ], [ "How do I calculate markup?", "(Price − cost) ÷ cost × 100: $20 ÷ $80 = 25%." ], [ "Which number should I use?", "Margin for business health; markup for pricing from cost. Know which one you're being quoted." ], [ "How do I set a price for a target margin?", "Price = cost ÷ (1 − margin): $80 ÷ 0.80 = $100 for 20%." ], [ "Is this gross or net margin?", "Gross — before overhead. Net margin subtracts operating costs." ], [ "Why does my supplier quote markup but my store tracks margin?", "Different conventions — suppliers price from cost; retailers measure revenue share. The converter bridges them." ], [ "What is the difference between margin and markup?", "Margin is profit ÷ revenue; markup is profit ÷ cost." ], [ "How do I calculate margin?", "(Price − cost) ÷ price × 100." ], [ "How do I price for a target margin?", "Cost ÷ (1 − margin): $30 ÷ 0.6 = $50 for a 40% margin." ] ] }, { "slug": "project-quote-calculator", "name": "Project Quote Calculator", "canonical_url": "https://boringtoolskit.com/project-quote-calculator/", "category": "Time & Work", "description": "Project quote calculator: labor plus materials estimate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "property-area-calculator", "name": "Property Area Calculator", "canonical_url": "https://boringtoolskit.com/property-area-calculator/", "category": "Real Estate", "description": "Convert property and land area between square feet, square meters, acres, hectares, and square yards.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/square-footage-calculator/", "/market-value-calculator/", "/renovation-calculator/" ], "answer": "Convert property and land area between square feet, square meters, acres, hectares, and square yards.", "formula": "Conversion between square feet, square meters, acres, hectares, and square yards using metric bases: 1 sq ft = 0.09290304 m², 1 sq yd = 0.83612736 m², 1 acre = 4,046.8564224 m², 1 hectare = 10,000 m². Value in target unit = value × base(unit) ÷ base(target).", "example": "1 acre = 4,046.8564224 ÷ 0.09290304 = 43,560 square feet.", "assumptions": [ "Standard international definitions of the units are used.", "Values are exact area measures, not rounded land measures.", "No shape or survey information is required for a unit conversion." ], "sources": [ { "organization": "NIST", "title": "SI Units – Area", "url": "https://www.nist.gov/pml/owm/metric-si/si-units-area" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How many square feet are in an acre?", "Exactly 43,560 square feet (1 acre = 4,046.8564224 m², and 1 m² = 10.7639 sq ft)." ], [ "How many acres in a hectare?", "1 hectare = 10,000 m² ≈ 2.471 acres." ], [ "What is the difference between an acre and a hectare?", "An acre is the US/UK land measure (43,560 sq ft); a hectare is the metric measure (10,000 m²). A hectare is about 2.47 acres." ], [ "How do I convert square meters to square feet?", "Multiply square meters by 10.7639. The tool shows this and every other pairing in one table." ], [ "What is a square yard?", "A square yard = 9 sq ft (a yard is 3 feet, so 3×3). It's used in flooring, fabric, and landscaping in the US/UK." ], [ "Why would I need to convert property area?", "Comparing listings across regions (sq ft vs m²), reading international floor plans, or understanding parcel sizes in acres vs hectares." ], [ "Is the conversion exact?", "Yes — the tool uses the standard international definitions exactly. For an irregular lot, the area itself must come from a survey; the conversion of that area is exact." ] ] }, { "slug": "property-management-fee-calculator", "name": "Property Management Fee Calculator", "canonical_url": "https://boringtoolskit.com/property-management-fee-calculator/", "category": "Real Estate", "description": "Property management fee calculator: monthly and annual management fees plus a lease placement fee.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "property-tax-calculator", "name": "Property Tax Calculator", "canonical_url": "https://boringtoolskit.com/property-tax-calculator/", "category": "Real Estate", "description": "Estimate annual property tax from assessed value, tax rate, and exemptions for budgeting.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/mortgage-payment-calculator/", "/closing-cost-calculator/", "/mortgage-afford/" ], "answer": "Estimate annual property tax from assessed value, tax rate, and exemptions for budgeting.", "formula": "Property tax = (assessed value − exemptions − deductions) × tax rate ÷ 100, computed annually and divided by 12 for the monthly amount.", "example": "An assessed value of $300,000 with a $25,000 exemption and a 1.25% rate: taxable = $275,000, annual tax = $275,000 × 0.0125 = $3,437.50, or about $286/month.", "assumptions": [ "Assessed value and rate are entered by the user.", "Exemptions/deductions reduce the taxable value.", "The estimate is annual tax, divided by 12 for monthly." ], "sources": [ { "organization": "Investopedia", "title": "Property Tax", "url": "https://www.investopedia.com/terms/p/property-tax.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How is property tax calculated?", "Property tax = (assessed value − exemptions) × tax rate ÷ 100, usually annual then divided by 12 for monthly." ], [ "What is the assessed value?", "The value a local assessor assigns for tax purposes, which may be a percentage of market value. It can differ from what you paid or the current appraisal." ], [ "How do exemptions affect it?", "Exemptions (like a homestead or primary-residence credit) reduce the taxable value before the rate is applied, lowering your bill." ], [ "Does property tax change every year?", "Yes. Assessed values are recalculated periodically and local tax rates are set annually, so your bill can rise or fall. Budget for possible increases." ], [ "Why is my property tax higher than the estimate?", "The assessor's valuation, the actual rate, or additional local levies (school, village, bond) can push it up beyond a single-rate estimate." ], [ "Is property tax included in my mortgage payment?", "Often yes — many lenders escrow the property tax and insurance into your monthly payment, so it's paid alongside the mortgage. Check your escrow statement." ], [ "What is a millage rate?", "A tax rate expressed in 'mills' per $1,000 of taxable value. A 12.5-mill rate equals 1.25%. It's the local government's way of stating the rate." ] ] }, { "slug": "proportion-solver", "name": "Proportion Solver", "canonical_url": "https://boringtoolskit.com/proportion-solver/", "category": "Everyday Calculators", "description": "Proportion solver: solve a/b = c/d for the unknown.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-27", "related_urls": [], "answer": "Proportion solver: solve a/b = c/d for the unknown.", "formula": "If a/b = c/d, then d = (b × c) / a.", "example": "2/5 = 8/d → d = (5 × 8)/2 = 20.", "assumptions": [ "Standard geometric or arithmetic definitions apply.", "Inputs use the units you choose.", "Results are estimates, not professional advice." ], "sources": [ { "organization": "Standard mathematics definitions", "title": "Arithmetic and geometry formulas", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "prorated-rent-calculator", "name": "Prorated Rent Calculator", "canonical_url": "https://boringtoolskit.com/prorated-rent-calculator/", "category": "Real Estate", "description": "Prorated rent calculator: how much rent to charge for a partial month move-in or move-out.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "protein-molecular-weight-calculator", "name": "Protein Molecular Weight Calculator", "canonical_url": "https://boringtoolskit.com/protein-molecular-weight-calculator/", "category": "Biology", "description": "Protein molecular weight calculator: approximate mass from amino acid chain length.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "protein-shake-calculator", "name": "Protein Shake Calculator", "canonical_url": "https://boringtoolskit.com/protein-shake-calculator/", "category": "Health", "description": "Protein shake calculator: protein per shake from scoops.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "pto-accrual-calculator", "name": "PTO Accrual Calculator", "canonical_url": "https://boringtoolskit.com/pto-accrual-calculator/", "category": "Time & Work", "description": "PTO accrual calculator: vacation hours per year from a pay-period rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "pulse-pressure-calculator", "name": "Pulse Pressure Calculator", "canonical_url": "https://boringtoolskit.com/pulse-pressure-calculator/", "category": "Health", "description": "Pulse pressure calculator: the gap between systolic and diastolic.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "punnett-square-calculator", "name": "Punnett Square Calculator", "canonical_url": "https://boringtoolskit.com/punnett-square-calculator/", "category": "Biology", "description": "Punnett square calculator: monohybrid cross offspring genotype and phenotype probabilities.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "puppy-adult-weight-calculator", "name": "Puppy Adult Weight Calculator", "canonical_url": "https://boringtoolskit.com/puppy-adult-weight-calculator/", "category": "Pets", "description": "Puppy adult weight calculator: predicted adult weight from current age and weight.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "puppy-age-calculator", "name": "Puppy Age Calculator", "canonical_url": "https://boringtoolskit.com/puppy-age-calculator/", "category": "Pets", "description": "Dog age calculator: dog years to human years (AAHA method).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "puppy-breed-size-calculator", "name": "Puppy Breed Size Calculator", "canonical_url": "https://boringtoolskit.com/puppy-breed-size-calculator/", "category": "Pets", "description": "Puppy breed size calculator: adult weight by breed category.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "push-up-test-calculator", "name": "Push Up Test Calculator", "canonical_url": "https://boringtoolskit.com/push-up-test-calculator/", "category": "Sports", "description": "Push up test calculator: fitness rating by age and reps.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "pythagorean-theorem-calculator", "name": "Pythagorean Theorem Calculator", "canonical_url": "https://boringtoolskit.com/pythagorean-theorem-calculator/", "category": "Everyday Calculators", "description": "Find the missing side of a right triangle using a² + b² = c².", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/quadratic-formula-calculator/", "/triangle-calculator/", "/circle-calculator/" ], "answer": "Find the missing side of a right triangle using a² + b² = c².", "formula": "a² + b² = c², where c is the hypotenuse. Solving for the hypotenuse: c = √(a² + b²). Solving for a leg: a = √(c² − b²) or b = √(c² − a²).", "example": "A right triangle with legs 3 and 4 has hypotenuse c = √(9 + 16) = √25 = 5. Given hypotenuse 13 and leg 5, the other leg is √(169 − 25) = √144 = 12.", "assumptions": [ "The triangle is right-angled.", "All side lengths are in the same units.", "The known leg is shorter than the hypotenuse when solving for a leg." ], "sources": [ { "organization": "Math Is Fun", "title": "Pythagoras' Theorem", "url": "https://www.mathsisfun.com/pythagoras.html" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is the Pythagorean theorem?", "a² + b² = c²: in a right triangle, the square of the hypotenuse equals the sum of the squares of the other two sides." ], [ "How do I find the hypotenuse?", "Take the square root of the sum of the squares: c = √(a² + b²)." ], [ "How do I find a missing leg?", "Subtract the square of the known leg from the square of the hypotenuse, then take the root: a = √(c² − b²)." ], [ "Does it work for non-right triangles?", "No — the theorem applies only to right triangles. Other triangles use the law of cosines." ], [ "Why is the hypotenuse the longest side?", "Because it's opposite the right angle (90°), and the side opposite the largest angle is always the longest in any triangle." ], [ "What are common applications?", "Computing straight-line distances, ladder reach, TV/screen diagonals, roof pitches, and navigation offsets." ], [ "What if the result is undefined?", "If the known leg is longer than the hypotenuse you entered, no real triangle exists — check that the hypotenuse is the largest value." ] ] }, { "slug": "qr-generator", "name": "QR Code Generator", "canonical_url": "https://boringtoolskit.com/qr-generator/", "category": "Generators", "description": "Generate a QR code and download a PNG.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/base64-tool/", "/text-case/", "/random-number-generator/" ], "answer": "Generate a QR code and download a PNG.", "formula": "A QR code encodes data (text or URL) into a grid of black and white modules. Error correction (L/M/Q/H) and version (size) are chosen by the generator; the code encodes the payload plus redundancy so scanners can read it even when partially damaged.", "example": "Encoding 'https://boringtoolskit.com' produces a scannable QR code: point any phone camera at it to open the URL instantly.", "assumptions": [ "The payload is text or a URL.", "The generated code follows standard QR encoding.", "The scanner is a standard phone camera app." ], "sources": [ { "organization": "Wikipedia", "title": "QR code", "url": "https://en.wikipedia.org/wiki/QR_code" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a QR code?", "A two-dimensional barcode that stores data in a grid of modules, readable by phone cameras — commonly URLs, text, WiFi credentials, and contact info." ], [ "How do I generate one?", "Enter your text or URL, choose the size, and download the PNG. This tool generates locally in your browser — nothing is uploaded." ], [ "What can QR codes store?", "URLs, plain text, WiFi logins, email addresses, phone numbers, and more — up to a few thousand characters depending on version." ], [ "Why won't my code scan?", "Usually contrast, size, or margins: use dark-on-light colors, a large enough print size, and quiet-zone whitespace around the code." ], [ "What is error correction?", "Redundancy built into the code that lets scanners recover from damage — levels L (7%) to H (30%). More redundancy means a denser code." ], [ "Are QR codes safe to scan?", "Codes can point anywhere, including malicious sites — only scan codes from sources you trust, like this tool's output." ], [ "Why use a QR instead of a link?", "QRs bridge physical and digital: a printed poster, business card, or menu can instantly open a website or app." ] ] }, { "slug": "quadratic-formula-calculator", "name": "Quadratic Formula Calculator", "canonical_url": "https://boringtoolskit.com/quadratic-formula-calculator/", "category": "Everyday Calculators", "description": "Solve a quadratic equation ax² + bx + c = 0 and see the roots.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/pythagorean-theorem-calculator/", "/exponent-calculator/", "/fractions-calculator/" ], "answer": "Solve a quadratic equation ax² + bx + c = 0 and see the roots.", "formula": "For ax² + bx + c = 0, roots = (−b ± √(b² − 4ac)) ÷ 2a. The discriminant D = b² − 4ac decides the roots: D > 0 gives two real roots, D = 0 a double root, D < 0 complex roots. Sum of roots = −b/a, product = c/a.", "example": "x² − 5x + 6 = 0: discriminant = 25 − 24 = 1, so roots = (5 ± 1) ÷ 2 = 3 and 2.", "assumptions": [ "The equation is in standard form ax² + bx + c = 0.", "a is non-zero.", "Coefficients are real numbers." ], "sources": [ { "organization": "Math Is Fun", "title": "Quadratic Equation Solver", "url": "https://www.mathsisfun.com/algebra/quadratic-equation.html" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is the quadratic formula?", "x = (−b ± √(b² − 4ac)) ÷ 2a — the general solution to ax² + bx + c = 0." ], [ "What is the discriminant?", "D = b² − 4ac. D > 0 means two real roots, D = 0 one double root, D < 0 a pair of complex roots." ], [ "What if a is zero?", "The equation is linear (bx + c = 0), not quadratic — the formula doesn't apply, and this tool rejects it." ], [ "What are complex roots?", "When the discriminant is negative, the square root is imaginary and the roots are a complex pair (real ± imaginary·i). They mean the parabola never crosses the x-axis." ], [ "How do I check my answer?", "Plug each root back into ax² + bx + c — it should equal zero. The sum of roots equals −b/a and the product equals c/a as a quick cross-check." ], [ "What does the vertex have to do with it?", "The roots are symmetric around the vertex x = −b/(2a). The discriminant tells you whether the vertex sits below, on, or above the x-axis." ], [ "Can the formula solve any quadratic?", "Yes, for any real coefficients with a ≠ 0 — real or complex solutions included." ] ] }, { "slug": "quarter-mile-time-calculator", "name": "Quarter Mile Time Calculator", "canonical_url": "https://boringtoolskit.com/quarter-mile-time-calculator/", "category": "Vehicles", "description": "Quarter-mile time calculator: estimated ET and trap speed from horsepower and weight.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "quarterback-rating-calculator", "name": "Quarterback Rating Calculator", "canonical_url": "https://boringtoolskit.com/quarterback-rating-calculator/", "category": "Sports", "description": "Quarterback rating calculator: NFL passer rating from attempts, completions, yards, touchdowns, and interceptions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "quartile-calculator", "name": "Quartile Calculator", "canonical_url": "https://boringtoolskit.com/quartile-calculator/", "category": "Everyday Calculators", "description": "Calculate the first (Q1), second (median/Q2), and third (Q3) quartiles plus the interquartile range (IQR) of a data set.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/statistics-calculator/", "/percentile-calculator/", "/variance-calculator/" ], "answer": "Calculate the first (Q1), second (median/Q2), and third (Q3) quartiles plus the interquartile range (IQR) of a data set.", "formula": "Quartiles split the sorted data into four equal parts: Q1 is the median of the lower half, Q2 the median of the whole set, Q3 the median of the upper half. IQR = Q3 − Q1.", "example": "For data 1, 3, 5, 7, 9, 11 (n = 6): Q2 = 6 (mean of 5 and 7). Lower half 1,3,5 → Q1 = 3. Upper half 7,9,11 → Q3 = 9. IQR = 9 − 3 = 6.", "assumptions": [ "Quartiles need at least two values.", "The method splits the data at the median and takes the median of each half.", "Outliers can be flagged relative to the IQR, but the tool does not predict them." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "NIST/SEMATECH e-Handbook of Statistical Methods", "url": "https://www.itl.nist.gov/div898/handbook/" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "quote-estimate-generator", "name": "Quote / Estimate Generator", "canonical_url": "https://boringtoolskit.com/quote-estimate-generator/", "category": "Generators", "description": "Create a simple service quote or estimate with line items, taxes, deposits, payment terms, and a copyable client summary.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/invoice-gen/", "/receipt-generator/", "/payment-terms-generator/" ], "answer": "Create a simple service quote or estimate with line items, taxes, deposits, payment terms, and a copyable client summary.", "formula": "Line totals = quantity × unit price; subtotal = Σ lines; tax = subtotal × tax rate; total = subtotal + tax. The tool renders a client-ready quote from your line items.", "example": "3 × $200 design hours = $600 subtotal; with 0% tax, total = $600.", "assumptions": [ "Line items reflect the agreed scope.", "The tax rate is a flat percentage.", "Validity and payment terms are added by the user." ], "sources": [ { "organization": "Wikipedia", "title": "Invoice", "url": "https://en.wikipedia.org/wiki/Invoice" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is the difference between a quote and an estimate?", "A quote is a firm price commitment; an estimate is approximate and can change with scope. Label the document clearly." ], [ "How do I build a quote?", "Itemize every deliverable with quantity and price; the tool computes subtotal, tax, and total." ], [ "How are line items calculated?", "Each line = qty × price; subtotal is the sum; total = subtotal + tax." ], [ "What should a quote include?", "Your details, client, itemized scope and prices, tax, validity period, and payment terms." ], [ "How do I avoid scope disputes?", "Itemize deliverables explicitly and add 'additional work billed separately' to the terms." ], [ "Should I include validity?", "Yes — 'valid for 30 days' prevents clients from accepting a stale price months later." ], [ "Can I use this for services?", "Yes — service quotes are the most common use: hours × rate per deliverable." ], [ "What does a quote generator do?", "Builds an itemized estimate from line items, tax, and discount — ready to send." ], [ "How is the total calculated?", "Σ(quantity × unit price), then discount, then tax." ], [ "What is the difference from an invoice?", "A quote is an offer; an invoice bills for delivered work." ], [ "Should quotes expire?", "Yes — a validity period makes the estimate enforceable." ] ] }, { "slug": "raffle-odds-calculator", "name": "Raffle Odds Calculator", "canonical_url": "https://boringtoolskit.com/raffle-odds-calculator/", "category": "Gaming", "description": "Raffle odds calculator: win probability from tickets you hold vs total sold.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "rain-barrel-calculator", "name": "Rain Barrel Calculator", "canonical_url": "https://boringtoolskit.com/rain-barrel-calculator/", "category": "Construction & Measurement", "description": "Rain barrel calculator: gallons collected from roof runoff.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "raise-percentage-calculator", "name": "Raise Percentage Calculator", "canonical_url": "https://boringtoolskit.com/raise-percentage-calculator/", "category": "Time & Work", "description": "Raise percentage calculator: new salary after a percent raise.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "raised-bed-soil-calculator", "name": "Raised Bed Soil Calculator", "canonical_url": "https://boringtoolskit.com/raised-bed-soil-calculator/", "category": "Construction & Measurement", "description": "Raised bed soil calculator: soil volume for a garden bed.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "random-name-picker", "name": "Random Name Picker", "canonical_url": "https://boringtoolskit.com/random-name-picker/", "category": "Everyday Calculators", "description": "Draw one name from a list of names you enter, using unbiased local browser randomness. Add names one per line, then pick.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/random-number-generator/", "/prize-wheel/", "/coin-flip/" ], "answer": "Draw one name from a list of names you enter, using unbiased local browser randomness. Add names one per line, then pick.", "formula": "Draws one (or more) names from a user-entered list using unbiased local browser randomness (Web Crypto).", "example": "Entering 10 contest entries and drawing once selects one winner with equal odds for each entry.", "assumptions": [ "Each line is one entry.", "All entries are equal.", "The draw is casual, not certified." ], "sources": [ { "organization": "Wikipedia", "title": "Randomness", "url": "https://en.wikipedia.org/wiki/Randomness" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I pick a random name?", "Paste the list one name per line and draw — each entry has equal odds." ], [ "Can I draw multiple winners?", "Yes — set the count to draw several at once." ], [ "Is the draw fair?", "Each entry gets equal probability using the browser's cryptographic random source." ], [ "Do duplicate names matter?", "Yes — each line is one entry, so duplicates double that name's chances." ], [ "Can I remove a winner?", "Manually delete the drawn name before the next draw to avoid repeats." ], [ "What is this used for?", "Giveaways, classroom picks, team assignments, and decisions." ], [ "Is it legally binding?", "No — use a certified process for legally significant drawings." ] ] }, { "slug": "random-number-generator", "name": "Random Number Generator", "canonical_url": "https://boringtoolskit.com/random-number-generator/", "category": "Everyday Calculators", "description": "Generate one or up to 100 random integers from a custom range using unbiased local browser randomness.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/random-name-picker/", "/dice-roller/", "/coin-flip/" ], "answer": "Generate one or up to 100 random integers from a custom range using unbiased local browser randomness.", "formula": "Generates random integers in a chosen range, optionally unique and sorted, using a uniform random source.", "example": "Requesting 5 numbers from 1–100 produces a random set like 7, 42, 63, 88, 91.", "assumptions": [ "The range is valid (min ≤ max).", "Unique mode is possible for the range.", "The random source is adequate for the use." ], "sources": [ { "organization": "Wikipedia", "title": "Random number generation", "url": "https://en.wikipedia.org/wiki/Random_number_generation" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I generate random numbers?", "Set the min, max, and count — the tool draws uniform random integers from the range." ], [ "Can I avoid repeats?", "Yes — unique mode draws without repetition, when the range allows." ], [ "Are the numbers truly random?", "They use a strong pseudorandom source — suitable for practical use." ], [ "Can I use this for lottery picks?", "Yes — generate the count of numbers for your game's range." ], [ "Can I sort them?", "Yes — the sort option orders the draw." ], [ "What is it used for?", "Sampling, games, contests, and statistical demonstrations." ], [ "Is it good for passwords?", "No — use a dedicated password generator with cryptographic entropy." ] ] }, { "slug": "random-quote-generator", "name": "Random Quote Generator", "canonical_url": "https://boringtoolskit.com/random-quote-generator/", "category": "Generators", "description": "Get random motivational and wisdom quotes by topic, instantly and without an account.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "August 2026", "related_urls": [ "/dad-joke-generator/", "/pomodoro-timer/", "/quote-estimate-generator/" ], "answer": "Get random motivational and wisdom quotes by topic, instantly and without an account.", "formula": "Quotes are drawn from curated topic pools and shuffled. Select a topic or leave it on Random to mix categories.", "example": "Select Success to get quotes like 'Success is the sum of small efforts, repeated day in and day out.'", "assumptions": [ "Generated output is a starting point, not final professional copy.", "Nothing you type leaves your browser.", "Results vary on each run because selection is random." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculation methodology and verification standard", "url": "/methodology/" } ], "faqs": [ [ "Are the quotes real?", "They're curated from well-known public-domain and attributed quotes. Verify attribution before formal use." ], [ "Can I get a specific topic?", "Yes — pick Motivation, Wisdom, Success, Kindness, or Random." ], [ "Does it need internet?", "No. The quote pool is bundled and runs offline." ] ] }, { "slug": "random-team-splitter", "name": "Random Team Splitter", "canonical_url": "https://boringtoolskit.com/random-team-splitter/", "category": "Everyday Calculators", "description": "Split any list of names into balanced random teams instantly. Choose team count or members per team — runs entirely in your browser.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "rc-time-constant-calculator", "name": "RC Time Constant Calculator", "canonical_url": "https://boringtoolskit.com/rc-time-constant-calculator/", "category": "Energy & Electrical", "description": "RC time constant calculator: charge/discharge time constant and charge percentage.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "reaction-rate-calculator", "name": "Reaction Rate Calculator", "canonical_url": "https://boringtoolskit.com/reaction-rate-calculator/", "category": "Chemistry", "description": "Calculate reaction rate from concentration change over time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/equilibrium-constants-calculator/", "/buffer-solution-calculator/", "/percent-yield-calculator/" ], "answer": "Calculate reaction rate from concentration change over time.", "formula": "Rate = k × [A]^x × [B]^y, using the rate constant k and the reaction order for each concentration.", "example": "For k = 0.1, [A] = 2 M and order 1 (with [B] omitted): rate = 0.1 × 2 = 0.2 M/s.", "assumptions": [ "The rate constant and at least one concentration and its order are required.", "Concentration must be non-negative; [B] and its order are optional.", "The rate law is a constant-temperature empirical model." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "readability", "name": "Readability Calculator", "canonical_url": "https://boringtoolskit.com/readability/", "category": "Text & Developer Tools", "description": "Score text readability and grade level.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/word-counter/", "/keyword-density-calculator/", "/meta-tags/" ], "answer": "Score text readability and grade level.", "formula": "Flesch Reading Ease = 206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words). Score 90+ = very easy (children's text); 60–70 = plain English; below 30 = very difficult.", "example": "A passage with 15 words, 2 sentences, and 22 syllables scores ≈ 75 — 'fairly easy' reading, typical of conversational writing.", "assumptions": [ "English-language text with standard syllable patterns.", "The syllable-count heuristic is reasonable.", "The score is a readability guide, not a quality metric." ], "sources": [ { "organization": "Wikipedia", "title": "Flesch–Kincaid readability tests", "url": "https://en.wikipedia.org/wiki/Flesch%E2%80%93Kincaid_readability_tests" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is the Flesch Reading Ease score?", "A 0–100 readability score: 206.835 − 1.015×(words/sentences) − 84.6×(syllables/words). 90+ is very easy, 60–70 plain English, below 30 very difficult." ], [ "What score should my web content target?", "60+ is a good target for general audiences — roughly a 9th-grade reading level or below." ], [ "How is it calculated?", "The formula uses average sentence length and average syllables per word. Longer sentences and bigger words lower the score." ], [ "Is a high score always better?", "No — short sentences and simple words score easy even for complex topics, and some content needs precise vocabulary. Use it as a guide." ], [ "What is the grade level?", "The Flesch-Kincaid Grade Level converts the score to a US school grade; Reading Ease is the 0–100 form." ], [ "Does it work for technical text?", "It scores it — but technical terms and long words will show as 'difficult'. That's often appropriate for expert audiences." ], [ "How do I improve my score?", "Split long sentences, cut unnecessary clauses, and replace multi-syllable words with simpler alternatives." ] ] }, { "slug": "reading-speed-calculator", "name": "Reading Speed Calculator", "canonical_url": "https://boringtoolskit.com/reading-speed-calculator/", "category": "School & Education", "description": "Reading speed calculator: words per minute and book reading time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "reading-time-calculator", "name": "Reading Time Calculator", "canonical_url": "https://boringtoolskit.com/reading-time-calculator/", "category": "School & Education", "description": "Reading time calculator: how long a text takes to read at your words-per-minute pace.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "receipt-generator", "name": "Receipt Generator", "canonical_url": "https://boringtoolskit.com/receipt-generator/", "category": "Generators", "description": "Create a simple payment receipt with payer, seller, items, tax, payment method, and a copyable receipt summary.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/invoice-gen/", "/quote-estimate-generator/", "/payment-terms-generator/" ], "answer": "Create a simple payment receipt with payer, seller, items, tax, payment method, and a copyable receipt summary.", "formula": "Line totals = quantity × unit price; subtotal = Σ lines; tax = subtotal × tax rate; total = subtotal + tax. The tool renders a printable receipt with seller, buyer, and item lines.", "example": "1 × $75 service = $75 subtotal; with 0% tax, total = $75.", "assumptions": [ "The user enters accurate transaction details.", "Line items are entered as description, qty, price.", "The tax rate is a flat percentage of the subtotal." ], "sources": [ { "organization": "Wikipedia", "title": "Receipt", "url": "https://en.wikipedia.org/wiki/Receipt" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a receipt?", "Proof of a completed transaction — what was sold, to whom, and for how much." ], [ "How do I create one?", "Enter seller and buyer details, add item lines (description, qty, price), set tax, and generate." ], [ "What's the difference from an invoice?", "An invoice requests payment before/at billing; a receipt confirms payment already received." ], [ "Are receipts legally required?", "For many business sales, yes — check your jurisdiction's requirements for tax IDs, itemization, and retention." ], [ "How are totals calculated?", "Each line = qty × price; subtotal is the sum; total = subtotal + tax." ], [ "Should I keep copies?", "Yes — retain receipts for bookkeeping, returns, warranties, and tax records." ], [ "Can I use this for a business?", "Yes, but verify local receipt requirements and keep sequential numbering for clean records." ], [ "What does a receipt generator do?", "Creates an itemized receipt from business, customer, items, and tax." ], [ "What is the difference from an invoice?", "An invoice asks for payment; a receipt confirms it." ], [ "How is tax applied?", "On the subtotal after any discount — the standard order." ], [ "Why keep receipts?", "Expense tracking and tax substantiation." ] ] }, { "slug": "recipe-divider-calculator", "name": "Recipe Divider Calculator", "canonical_url": "https://boringtoolskit.com/recipe-divider-calculator/", "category": "Food & Cooking", "description": "Recipe divider calculator: split a recipe into fractions (half, third, quarter) with each ingredient scaled.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "regex-tester", "name": "Regex Tester", "canonical_url": "https://boringtoolskit.com/regex-tester/", "category": "Everyday Calculators", "description": "Test a regular expression pattern against a string, see highlighted matches and a live match count, all in your browser.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/csv-to-json/", "/text-case/", "/markdown-table-generator/" ], "answer": "Test a regular expression pattern against a string, see highlighted matches and a live match count, all in your browser.", "formula": "Tests a regular expression pattern against sample text, showing matches, groups, and non-matches in real time.", "example": "The pattern \\d{3}-\\d{2}-\\d{4} matches 123-45-6789 in a text of mixed content.", "assumptions": [ "JavaScript regex syntax applies.", "The sample text represents real input.", "Flags are applied as the user expects." ], "sources": [ { "organization": "Wikipedia", "title": "Regular expression", "url": "https://en.wikipedia.org/wiki/Regular_expression" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a regex tester?", "A tool that runs a regular expression against sample text and shows what matches." ], [ "How do I use it?", "Enter the pattern and text — the tool highlights matches and shows capture groups." ], [ "What regex syntax does it use?", "JavaScript-style syntax, the common baseline for web and node tooling." ], [ "What are capture groups?", "Parenthesized parts of the pattern that extract specific substrings: (\\d{3}) captures the area code." ], [ "Why is my pattern not matching?", "Check anchors, flags, escaping, and whether the pattern matches the actual text format." ], [ "What are common uses?", "Email/phone validation, log parsing, search-and-replace, and data extraction." ], [ "Does it work in Python?", "Mostly — Python adds minor differences; verify portability." ] ] }, { "slug": "remainder-calculator", "name": "Remainder Calculator", "canonical_url": "https://boringtoolskit.com/remainder-calculator/", "category": "Everyday Calculators", "description": "Remainder calculator: quotient and remainder of a division.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "renovation-calculator", "name": "Renovation Calculator", "canonical_url": "https://boringtoolskit.com/renovation-calculator/", "category": "Real Estate", "description": "Estimate renovation return on investment by comparing project cost, value added, and resale assumptions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/market-value-calculator/", "/price-per-square-foot/", "/property-area-calculator/" ], "answer": "Estimate renovation return on investment by comparing project cost, value added, and resale assumptions.", "formula": "Value recouped = value added ÷ project cost × 100. Renovation ROI = (value added − project cost) ÷ project cost × 100. Estimated new home value = current home value + value added.", "example": "A $50,000 kitchen remodel that adds $40,000 in value: value recouped = $40,000 ÷ $50,000 = 80%, ROI = −20%, and a $400,000 home becomes an estimated $440,000.", "assumptions": [ "Value added is entered by the user (from comps or agent guidance).", "Recouped value is the resale lift, not the total benefit of the project.", "The home's other characteristics stay constant." ], "sources": [ { "organization": "National Association of Realtors", "title": "Remodeling Impact Report", "url": "https://www.nar.realtor/research-and-statistics/research-reports/remodeling-impact" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is renovation ROI?", "The return a remodel produces on resale: (value added − cost) ÷ cost × 100. Most projects recoup less than 100%, so ROI is often negative in resale terms." ], [ "Which projects recoup the most?", "NAR's Remodeling Impact Report consistently shows kitchens, bathrooms, and exterior upgrades (like siding and entry doors) recoup a large share of cost. Returns vary by region and home price tier." ], [ "What does 'value recouped' mean?", "The percentage of the project cost you get back when you sell: value added ÷ cost × 100. 80% recouped means you recover 80 cents of every dollar spent." ], [ "Should I renovate if ROI is negative?", "Yes, if the project improves your life — resale return isn't the only benefit. Just don't expect to break even on every remodel, and avoid over-improving above your neighborhood's price ceiling." ], [ "How do I estimate value added?", "Compare recent sales of similar homes with and without the upgrade, or ask a local agent. National averages are a starting point, not a guarantee." ], [ "What is over-improving?", "Spending far more than the neighborhood supports — e.g., a luxury kitchen in a modest area. Buyers won't pay a premium for it, so the recoup drops." ], [ "Does the calculator include my enjoyment of the remodel?", "No — it measures the resale math only. The personal value of a better kitchen or bath is real but not priced in." ] ] }, { "slug": "rent-affordability-calculator", "name": "Rent Affordability Calculator", "canonical_url": "https://boringtoolskit.com/rent-affordability-calculator/", "category": "Finance & Investing", "description": "Estimate affordable rent using your income, chosen cap, debt, and savings. Your suggested maximum is the lower of the income cap or cash available.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/rent-vs-buy-calculator/", "/mortgage-afford/", "/paycheck-calc/" ], "answer": "Estimate affordable rent using your income, chosen cap, debt, and savings. Your suggested maximum is the lower of the income cap or cash available.", "formula": "Gross monthly income = annual income ÷ 12. Income-rule cap = gross × target % (usually 30%). Cash-based cap = gross − monthly debts − savings. Suggested rent = the lower of the two caps.", "example": "$72,000/year = $6,000/month; at the 30% rule, rent up to $1,800/month.", "assumptions": [ "The 30% gross-income guideline applies.", "Debts and savings are entered monthly.", "Utilities and insurance are separate." ], "sources": [ { "organization": "Wikipedia", "title": "Renting", "url": "https://en.wikipedia.org/wiki/Renting" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How much rent can I afford?", "The standard rule: no more than 30% of gross income. At $72k/year that's $1,800/month." ], [ "What is the 30% rule?", "A guideline that housing costs shouldn't exceed 30% of gross income — 25% is even more comfortable." ], [ "Do landlords use 3× income?", "Many require gross monthly income at least 3× the rent — the other side of the same rule." ], [ "What if I have debts?", "The cash-based cap subtracts debt payments and savings from your income — use the lower of the two caps." ], [ "Does this include utilities?", "No — add utilities, internet, and renter's insurance to the rent for the true housing cost." ], [ "Can I exceed 30% in expensive cities?", "Often necessary — but the cash-based cap shows what you can actually sustain. Cut elsewhere." ], [ "How do I negotiate rent?", "Compare comparable units, offer longer terms, and move in off-peak seasons — but start from what you can afford." ], [ "Is 30% of gross or take-home?", "The rule uses gross; your real budget should also be checked against take-home." ], [ "Do debts reduce the rent ceiling?", "Yes — the 36% total-debt version subtracts other payments from the housing allowance." ], [ "What if 30% is impossible in my city?", "Adjust the rule to reality, but keep total debt service manageable and track actual spending." ] ] }, { "slug": "rent-split-calculator", "name": "Rent Split Calculator", "canonical_url": "https://boringtoolskit.com/rent-split-calculator/", "category": "Finance & Investing", "description": "Rent split calculator: divide rent fairly by each roommate's income.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "rent-to-value-calculator", "name": "Rent-to-Value Calculator", "canonical_url": "https://boringtoolskit.com/rent-to-value-calculator/", "category": "Finance & Investing", "description": "Calculate the rent-to-value ratio and the 1% rule. Enter property value and monthly rent to screen a rental fast.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/rental-yield-calculator/", "/price-to-rent-ratio-calculator/", "/gross-rent-multiplier-calculator/" ], "answer": "Calculate the rent-to-value ratio and the 1% rule. Enter property value and monthly rent to screen a rental fast.", "formula": "Rent-to-value = annual rent ÷ property value × 100. It's the inverse framing of the price-to-rent ratio — the annual rent as a percentage of the property's price.", "example": "A property worth $300,000 renting for $24,000/year has a rent-to-value of $24,000 ÷ $300,000 = 8.0%.", "assumptions": [ "Annual rent is monthly rent × 12.", "Rent-to-value uses gross rent, not net operating income.", "It's a comparison metric, not a profit figure." ], "sources": [ { "organization": "Investopedia", "title": "Price-to-Rent Ratio", "url": "https://www.investopedia.com/terms/p/price-to-rent-ratio.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is rent-to-value?", "The annual rent as a percentage of the property's price — the inverse of the price-to-rent ratio." ], [ "How do I calculate it?", "Rent-to-value = (monthly rent × 12) ÷ property value × 100." ], [ "Is higher rent-to-value better?", "Generally yes for income — more rent per dollar of price. But a high figure can also signal a lower-cost or riskier market." ], [ "How is it different from gross yield?", "It's essentially the same idea from the other direction: gross yield = rent ÷ price; rent-to-value = the same ratio expressed as a percentage. They're equivalent framings." ], [ "What's a good number?", "An approximate guide: the price-to-rent ratio (inverse) at or below 15 — equivalent to a rent-to-value around 6.7% or higher — favors owning or investing." ], [ "Does it account for costs?", "No. It uses gross rent. Use cap rate or cash flow for the net picture." ], [ "Why use this versus price-to-rent?", "It's a matter of framing. Rent-to-value is intuitive as a percentage; price-to-rent is a clean ratio used in market analysis. Both read the same relationship." ] ] }, { "slug": "rent-vs-buy-calculator", "name": "Rent vs. Buy Calculator", "canonical_url": "https://boringtoolskit.com/rent-vs-buy-calculator/", "category": "Finance & Investing", "description": "Compare modeled buyer equity with a renter investment portfolio using explicit monthly cash flows.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/down-payment-calculator/", "/mortgage-payment-calculator/", "/mortgage-refinance-break-even/" ], "answer": "Compare modeled buyer equity with a renter investment portfolio using explicit monthly cash flows.", "formula": "Compares total costs over a horizon: buying (down payment, mortgage payments, taxes, insurance, maintenance, minus equity and appreciation) vs renting (rent, renter's insurance, minus investment returns on the saved down payment).", "example": "At 20% down, a 6.5% mortgage, and 3% appreciation on a $300,000 home vs $1,500/month rent over 10 years, the tool projects which side comes out ahead — usually buying wins on longer horizons with appreciation.", "assumptions": [ "The entered rates and growth assumptions are reasonable estimates.", "The buyer stays for the full horizon.", "Maintenance and taxes are approximated by the entered percentages." ], "sources": [ { "organization": "Wikipedia", "title": "Renting", "url": "https://en.wikipedia.org/wiki/Renting" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "Is it better to rent or buy?", "It depends on your horizon, local prices, and rates. Longer stays and rising rents favor buying; short stays and high prices favor renting." ], [ "How does the calculator work?", "It projects total costs of both paths over your horizon: mortgage interest, taxes, and maintenance vs rent, plus equity/appreciation vs investment returns." ], [ "Why is buying better long-term?", "You build equity, and appreciation compounds on a large asset. But that only pays off if you stay long enough to cover the upfront costs." ], [ "Why is renting better short-term?", "No down payment, no maintenance, and the money you save can be invested — with low transaction costs when you move." ], [ "What are hidden costs of buying?", "Closing costs, maintenance (1–3% of home value per year), property taxes, insurance, and the illiquidity of the investment." ], [ "How long must I stay to make buying worth it?", "Common guidance is 5–7 years, but the real number depends on local prices, rents, and rates — the calculator shows your specific break-even." ], [ "What assumptions should I use?", "Current mortgage rates, realistic rent growth (2–4%), home appreciation (2–4% historical), and your actual investment returns." ], [ "How long must I stay for buying to win?", "Commonly 4–7 years at current rates, but it varies by market." ], [ "Does the down payment have a cost?", "Yes — its forgone investment return is a real cost of buying." ], [ "What about maintenance?", "About 1% of home value per year — a real cost renters don't pay." ] ] }, { "slug": "rental-car-cost-calculator", "name": "Rental Car Cost Calculator", "canonical_url": "https://boringtoolskit.com/rental-car-cost-calculator/", "category": "Travel", "description": "Rental car cost calculator: full rental cost including insurance, gas, and daily rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "rental-cash-flow-calculator", "name": "Rental Cash Flow Calculator", "canonical_url": "https://boringtoolskit.com/rental-cash-flow-calculator/", "category": "Real Estate", "description": "Rental cash flow calculator: monthly net cash flow after all costs.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "rental-property-roi-calculator", "name": "Rental Property ROI Calculator", "canonical_url": "https://boringtoolskit.com/rental-property-roi-calculator/", "category": "Finance & Investing", "description": "Estimate total return on a rental property. Combine cash flow, loan paydown, and appreciation over your holding period.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/cash-on-cash-return-calculator/", "/cash-flow-calculator/", "/cap-rate-calculator/" ], "answer": "Estimate total return on a rental property. Combine cash flow, loan paydown, and appreciation over your holding period.", "formula": "Rental property ROI = (total return ÷ total cash invested) × 100, where total return = cumulative cash flow + appreciation gain + principal paydown, and total cash invested is your down payment (plus any equity put in).", "example": "A $60,000 down payment property that produces $9,000/year cash flow over 5 years ($45,000), $25,000 in appreciation, and $12,000 in principal paydown gives a total return of $82,000 — an ROI of $82,000 ÷ $60,000 ≈ 137% over the period.", "assumptions": [ "Annual cash flow is pre-tax and held constant across years.", "Appreciation is applied to property value over the holding period.", "ROI is divided by the down payment (cash invested)." ], "sources": [ { "organization": "Investopedia", "title": "Cash-on-Cash Return", "url": "https://www.investopedia.com/terms/c/cash-on-cash-return.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate rental property ROI?", "ROI = (total cash flow + appreciation + principal paydown) ÷ cash invested × 100." ], [ "What counts as cash invested?", "Usually your down payment and any additional capital you put in. Financing (the loan) is excluded — it's leveraged, not your cash." ], [ "How is ROI different from cash-on-cash return?", "Cash-on-cash is a single-year cash yield. ROI is a multi-year total return that adds appreciation and principal paydown — a fuller, longer-view measure." ], [ "Is appreciation guaranteed?", "No. Appreciation is an assumption. Model a conservative rate, and remember the return depends on the market actually delivering it." ], [ "Why does the number grow over time?", "Because returns compound across years: you collect cash flow each year, the property appreciates, and you build equity via principal paydown." ], [ "Does ROI include taxes and selling costs?", "Not by default. For a true net return, subtract selling costs and account for tax. The raw figure is a pre-sale, pre-tax total return." ], [ "Is a 10% ROI good?", "It depends on your alternatives and risk. Compare to what your cash could earn elsewhere, and account for the risk and illiquidity of real estate." ] ] }, { "slug": "rental-yield-calculator", "name": "Rental Yield Calculator", "canonical_url": "https://boringtoolskit.com/rental-yield-calculator/", "category": "Finance & Investing", "description": "Calculate gross rental yield. Enter property price and annual rent for the quick first-pass screen on a rental.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/cap-rate-calculator/", "/gross-rent-multiplier-calculator/", "/price-to-rent-ratio-calculator/" ], "answer": "Calculate gross rental yield. Enter property price and annual rent for the quick first-pass screen on a rental.", "formula": "Gross rental yield = annual rent ÷ property value × 100. Monthly rent × 12 gives the annual rent, divided by the property price to get the yield as a percentage.", "example": "A property worth $300,000 renting for $2,000/month ($24,000/year) has a gross yield of $24,000 ÷ $300,000 = 8.0%.", "assumptions": [ "Gross yield uses annual rent before any operating expenses.", "Property value is the purchase price or current market value.", "This is a gross metric — it does not include financing or costs." ], "sources": [ { "organization": "Investopedia", "title": "Capitalization Rate", "url": "https://www.investopedia.com/terms/c/capitalization-rate.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a good gross rental yield?", "It varies by market. Many investors target 8%+ gross, but a lower yield in a stable, appreciating market can outperform a high-yield property in a declining one." ], [ "Is gross yield the same as cap rate?", "No. Gross yield divides annual rent by price; cap rate divides net operating income by price. Cap rate subtracts operating costs; gross yield does not." ], [ "Does gross yield include the mortgage?", "No. Gross yield is before financing and before operating costs — it's a pure income-to-price ratio." ], [ "How do I calculate gross yield?", "Gross yield = (monthly rent × 12) ÷ property value × 100." ], [ "Why is my yield higher than my cash return?", "Because yield uses full price and ignores the mortgage, while cash-on-cash return uses your down payment and subtracts costs." ], [ "Is a higher gross yield always better?", "Not necessarily. High gross yield can reflect a lower-cost or riskier area. Balance yield with appreciation, tenant quality, and vacancy." ], [ "What is monthly rent used for here?", "The calculator takes monthly rent and multiplies by 12 to get annual rent, which is the numerator of the gross yield." ] ] }, { "slug": "resistor-calculator", "name": "Resistor Color Code Calculator", "canonical_url": "https://boringtoolskit.com/resistor-calculator/", "category": "Physics", "description": "Resistor color code calculator: 4-band resistor value and tolerance from color bands.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "retainer-calculator", "name": "Retainer Calculator", "canonical_url": "https://boringtoolskit.com/retainer-calculator/", "category": "Time & Work", "description": "Retainer calculator: monthly retainer from hourly rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "retirement-planning-calculator", "name": "Retirement Planning Calculator", "canonical_url": "https://boringtoolskit.com/retirement-planning-calculator/", "category": "Finance & Investing", "description": "Project retirement savings, inflation-adjusted value, contributions, and a planning withdrawal estimate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/future-value-calculator/", "/savings-goal-calculator/", "/compound-interest/" ], "answer": "Project retirement savings, inflation-adjusted value, contributions, and a planning withdrawal estimate.", "formula": "Each month: balance = prior balance × (1 + annual return ÷ 12) + contribution; real value discounts the result by inflation.", "example": "", "assumptions": [ "Returns, inflation, and contributions remain constant.", "Contributions are made at month-end and taxes/fees are excluded.", "The withdrawal rate is a planning input, not a guarantee that savings will last." ], "sources": [ { "organization": "Investor.gov", "title": "Compound interest calculator and investor education", "url": "https://www.investor.gov/financial-tools-calculators/calculators/compound-interest-calculator" }, { "organization": "Department of Labor", "title": "Taking the mystery out of retirement planning", "url": "https://www.dol.gov/agencies/ebsa/about-ebsa/our-activities/resource-center/publications/taking-the-mystery-out-of-retirement-planning" } ], "faqs": [ [ "How does this retirement calculator work?", "This retirement calculator runs entirely in your browser — it uses your inputs like age, savings, and expected contributions to project your retirement readiness using standard compound growth formulas. No data is sent to a server." ], [ "Is my personal information safe and private?", "Yes. This retirement calculator requires no signup or account creation. All calculations happen locally on your device, and nothing — not your age, income, or savings — is stored, shared, or transmitted anywhere." ], [ "How accurate are the results from this retirement calculator?", "The retirement calculator provides estimates based on the assumptions you enter, such as your retirement age, expected returns, and inflation rate. It is a planning tool, not a financial advisor, and actual results may vary based on market conditions and lifestyle changes." ] ] }, { "slug": "retirement-withdrawal-calculator", "name": "Retirement Withdrawal Calculator", "canonical_url": "https://boringtoolskit.com/retirement-withdrawal-calculator/", "category": "Finance & Investing", "description": "Retirement withdrawal calculator: safe annual and monthly withdrawals from a portfolio using the 4% rule.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "return-on-investment-calculator", "name": "Return on Investment Calculator", "canonical_url": "https://boringtoolskit.com/return-on-investment-calculator/", "category": "Finance & Investing", "description": "Return on investment calculator: ROI from cost and gain.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "rgb-to-hex-calculator", "name": "RGB to Hex Converter", "canonical_url": "https://boringtoolskit.com/rgb-to-hex-calculator/", "category": "Colors & Design", "description": "RGB to hex converter: convert red, green, blue values (0–255) to a #RRGGBB hex color instantly.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "rice-water-ratio-calculator", "name": "Rice Water Ratio Calculator", "canonical_url": "https://boringtoolskit.com/rice-water-ratio-calculator/", "category": "Food & Cooking", "description": "Rice water ratio calculator: water per cup of rice by type.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "ring-size-calculator", "name": "Ring Size Calculator", "canonical_url": "https://boringtoolskit.com/ring-size-calculator/", "category": "Converters", "description": "Ring size calculator: US ring size from finger circumference.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "rmd-calculator", "name": "RMD Calculator", "canonical_url": "https://boringtoolskit.com/rmd-calculator/", "category": "Everyday Calculators", "description": "Estimate the Required Minimum Distribution from a retirement account at age 73+.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/retirement-planning-calculator/", "/401k-employer-match-calculator/", "/roth-ira-calculator/" ], "answer": "Estimate the Required Minimum Distribution from a retirement account at age 73+.", "formula": "RMD = account balance ÷ IRS life-expectancy factor. The tool uses the Uniform Lifetime Table factors: 26.5 at age 73, 24.6 at 75, 22.0 at 78, 20.2 at 80, 16.8 at 85, and 12.9 at 90 (falls back to 24.6 for other ages).", "example": "A $500,000 traditional IRA at age 73: RMD = $500,000 ÷ 26.5 ≈ $18,867.92 for the year.", "assumptions": [ "The IRS Uniform Lifetime Table factor for the entered age is used.", "The balance is the prior year-end account value.", "No spousal or inherited-account table applies." ], "sources": [ { "organization": "Investopedia", "title": "Required Minimum Distribution (RMD)", "url": "https://www.investopedia.com/terms/r/requiredminimumdistribution.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is an RMD?", "A required minimum distribution is the annual minimum amount the IRS requires you to withdraw from tax-deferred retirement accounts once you reach a specified age, so the deferred taxes are eventually paid." ], [ "When do RMDs start?", "Under SECURE 2.0, RMDs begin at age 73 for those who turn 73 after 2022 (rising to 75 for those born in 1960 or later). Confirm your exact required beginning date." ], [ "How is the RMD calculated?", "Divide your prior year-end account balance by the IRS life-expectancy factor for your age. For example, $500,000 ÷ 26.5 at age 73 ≈ $18,868." ], [ "What happens if I miss an RMD?", "You owe a 25% excise tax on the amount not withdrawn — reduced to 10% if you correct it promptly (within two years)." ], [ "Do Roth accounts have RMDs?", "No. Roth IRAs have no RMDs during the owner's lifetime, which is one reason they're useful for retirement tax planning." ], [ "Can I take one RMD from several accounts?", "For IRAs, yes — you can aggregate and take the total RMD from one account. For 401(k)s and 403(b)s, each plan generally requires its own RMD." ], [ "Can I withdraw more than the minimum?", "Yes — you can always withdraw more. The RMD is a floor, not a cap, and larger withdrawals may make sense for tax planning." ], [ "How is it calculated?", "Prior year-end balance ÷ the IRS life-expectancy factor for your age." ], [ "What is the penalty for missing one?", "25% of the missed amount (10% if corrected quickly)." ], [ "Do Roth IRAs have RMDs?", "Not during the owner's lifetime — traditional accounts do." ] ] }, { "slug": "road-trip-cost-calculator", "name": "Road Trip Cost Calculator", "canonical_url": "https://boringtoolskit.com/road-trip-cost-calculator/", "category": "Vehicles", "description": "Road trip cost calculator: fuel, hotels, and food for a trip.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "road-trip-time-calculator", "name": "Road Trip Time Calculator", "canonical_url": "https://boringtoolskit.com/road-trip-time-calculator/", "category": "Everyday Calculators", "description": "Road trip time calculator: drive time and arrival from distance, speed, and stops.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "roman-numeral-converter", "name": "Roman Numeral Converter", "canonical_url": "https://boringtoolskit.com/roman-numeral-converter/", "category": "Converters", "description": "Convert between decimal numbers and Roman numerals (1–4999) in either direction with validation.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "August 2026", "related_urls": [ "/scientific-notation-converter/", "/percentage-calc/", "/general-scientific-calculator/" ], "answer": "Convert between decimal numbers and Roman numerals (1–4999) in either direction with validation.", "formula": "Decimal to Roman: repeatedly subtract the largest available symbol (M, CM, D, CD, C, XC, L, XL, X, IX, V, IV, I). Roman to decimal: add each symbol, subtracting when a smaller symbol precedes a larger one.", "example": "1984 in Roman numerals is MCMLXXXIV. MCMLXXXIV back to decimal is 1984.", "assumptions": [ "Standard (non-overline) Roman numerals are used, covering 1–4999.", "Subtractive notation (IV, IX, XL, XC, CD, CM) is recognized." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculation methodology and verification standard", "url": "/methodology/" } ], "faqs": [ [ "How do you convert a decimal number to Roman numerals?", "Break the number into its largest place values using the symbols I, V, X, L, C, D, M (with subtractive pairs IV, IX, XL, XC, CD, CM) and concatenate them from largest to smallest." ], [ "What is the largest number supported?", "This calculator supports 1 through 4999, which is the practical limit of standard Roman numeral notation." ], [ "How do I convert a Roman numeral back to a number?", "Read each symbol left to right: if a smaller symbol precedes a larger one, subtract it; otherwise add it. The calculator validates the input and returns the decimal value." ] ] }, { "slug": "roof-pitch-calculator", "name": "Roof Pitch Calculator", "canonical_url": "https://boringtoolskit.com/roof-pitch-calculator/", "category": "Construction & Measurement", "description": "Roof pitch calculator: roof angle and slope factor from rise per foot of run.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "roofing-calculator", "name": "Roofing Calculator", "canonical_url": "https://boringtoolskit.com/roofing-calculator/", "category": "Construction & Measurement", "description": "Estimate roof area, roofing squares, and shingle bundles from footprint and pitch.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/square-footage-calculator/", "/concrete-calculator/", "/sonotube-concrete-column/" ], "answer": "Estimate roof area, roofing squares, and shingle bundles from footprint and pitch.", "formula": "Pitch factor = √(1 + (rise ÷ 12)²). Roof area = length × width × pitch factor. Area with waste = roof area × (1 + waste%). Roofing squares = total ÷ 100. Bundles ≈ squares × 3 (three bundles per square).", "example": "A 40 × 30 ft roof with a 6/12 pitch: pitch factor = √(1 + 0.5²) ≈ 1.118, roof area ≈ 1,341.6 sq ft. With 10% waste: ≈ 1,475.8 sq ft = 14.76 squares → about 45 bundles.", "assumptions": [ "A simple sloped (gable-style) roof geometry.", "Rise is inches of vertical per 12 inches of horizontal run.", "3 bundles of shingles per roofing square." ], "sources": [ { "organization": "Wikipedia", "title": "Roofing", "url": "https://en.wikipedia.org/wiki/Roofing" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a roofing square?", "A roofing square is 100 square feet of roof surface. Roofing materials (shingles, underlayment) are quoted per square." ], [ "How do I calculate roof area?", "Multiply the building footprint area by the pitch factor: √(1 + (rise ÷ 12)²). A 40×30 ft footprint with 6/12 pitch is about 1,342 sq ft of roof." ], [ "What is roof pitch?", "The slope of the roof, expressed as rise over 12 inches of run — a 6/12 pitch rises 6 inches per 12 inches of horizontal run." ], [ "How many bundles of shingles do I need?", "About 3 bundles per roofing square (some products cover more). For 15 squares, plan on about 45 bundles." ], [ "Why is the roof bigger than the footprint?", "Because it's sloped — the steeper the pitch, the larger the surface area for the same footprint." ], [ "Does this include overhangs and valleys?", "No. Add the eave overhang to your footprint measurement and expect more waste for valleys, hips, and dormers." ], [ "What else do I need besides shingles?", "Underlayment (felt or synthetic), flashing, ridge caps, nails, and starter strips. This calculator estimates shingle quantities only." ], [ "How do I estimate roofing material?", "Footprint × pitch factor ÷ 100 = squares; add 10–15% waste." ], [ "Does roof pitch matter?", "Yes — steeper roofs have more surface for the same footprint." ], [ "How many bundles per square?", "Typically 3 bundles per square for standard three-tab and architectural shingles." ] ] }, { "slug": "root-calculator", "name": "Root Calculator", "canonical_url": "https://boringtoolskit.com/root-calculator/", "category": "School & Education", "description": "Root calculator: the nth root of any number, including cube and fourth roots.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "roth-ira-calculator", "name": "Roth IRA Calculator", "canonical_url": "https://boringtoolskit.com/roth-ira-calculator/", "category": "Everyday Calculators", "description": "Estimate the future value of a Roth IRA with annual contributions and tax-free growth.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/compound-interest/", "/investment-return-calculator/", "/retirement-planning-calculator/" ], "answer": "Estimate the future value of a Roth IRA with annual contributions and tax-free growth.", "formula": "Future value = current balance × (1 + rate)^years + annual contribution × [((1 + rate)^years − 1) ÷ rate]. It compounds your existing balance and each year's contribution at the assumed annual return.", "example": "A $10,000 Roth IRA growing at 7% with $6,000 contributed annually for 30 years: future value ≈ $10,000×1.07^30 + $6,000×[(1.07^30−1)/0.07] ≈ $76,122 + $566,764 ≈ $642,886.", "assumptions": [ "Contributions are made at the end of each year.", "A single constant annual return is assumed.", "The estimate excludes fees and income/contribution limits." ], "sources": [ { "organization": "Investopedia", "title": "Roth IRA", "url": "https://www.investopedia.com/terms/r/roth-ira.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a Roth IRA?", "A retirement account funded with after-tax dollars. The money grows tax-free and qualified withdrawals are tax-free." ], [ "Who can contribute to a Roth IRA?", "Anyone with earned income under the IRS income limit. Above a threshold, contributions phase out; high earners can't contribute directly." ], [ "What is the contribution limit?", "It's set by the IRS annually. For 2025 it's $7,000, with a $1,000 catch-up for those 50+. Confirm the current year's limit." ], [ "How is a Roth different from a traditional IRA?", "Traditional contributions are tax-deductible but withdrawals are taxed; Roth contributions are post-tax but withdrawals are tax-free. Roth wins if you expect higher taxes in retirement." ], [ "When can I withdraw tax-free?", "Qualified distributions after age 59½ and 5 years from the first contribution. Contributions can be withdrawn anytime tax-free (but not earnings)." ], [ "What return should I assume?", "Historically broad-market stock returns have averaged 7–10% nominal, but past performance isn't guaranteed. Use a conservative rate." ], [ "Is the estimate guaranteed?", "No. It's a projection based on your assumed return. Real results vary with market performance, fees, and contribution timing." ] ] }, { "slug": "round-up-down-calculator", "name": "Round Up Down Calculator", "canonical_url": "https://boringtoolskit.com/round-up-down-calculator/", "category": "Everyday Calculators", "description": "Round up/down calculator: nearest multiple in both directions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-27", "related_urls": [], "answer": "Round up/down calculator: nearest multiple in both directions.", "formula": "Round to the chosen place: look at the digit to its right; 0–4 rounds down, 5–9 rounds up (round half up).", "example": "3.14159 rounded to 2 decimals is 3.14; to 3 decimals is 3.142.", "assumptions": [ "Standard geometric or arithmetic definitions apply.", "Inputs use the units you choose.", "Results are estimates, not professional advice." ], "sources": [ { "organization": "Standard mathematics definitions", "title": "Arithmetic and geometry formulas", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "rounding-numbers-calculator", "name": "Rounding Numbers Calculator", "canonical_url": "https://boringtoolskit.com/rounding-numbers-calculator/", "category": "Everyday Calculators", "description": "Round any number to the nearest ten, one, tenth, hundredth, or thousandth , with every place shown at once.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/numbers-to-words/", "/percentage-calc/", "/order-of-operations-calculator/" ], "answer": "Round any number to the nearest ten, one, tenth, hundredth, or thousandth , with every place shown at once.", "formula": "Rounds a number to a chosen number of decimal places: 3.14159 → 3.14 at 2 places. The tool also shows the nearest integer and significant-value forms.", "example": "3.14159 rounded to 2 decimal places = 3.14.", "assumptions": [ "Standard half-up rounding applies.", "Decimal places are non-negative.", "The result is for display or reporting." ], "sources": [ { "organization": "Wikipedia", "title": "Rounding", "url": "https://en.wikipedia.org/wiki/Rounding" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I round a number?", "Look at the next digit: 5+ rounds up, below 5 down. 3.14159 → 3.14 at 2 places." ], [ "What is half-up rounding?", "The standard rule: ties (exactly 5) round up. Banker's rounding rounds ties to even instead." ], [ "Can I round to whole numbers?", "Yes — 0 decimal places gives the nearest integer." ], [ "Why does my total look off?", "Rounding each line item before summing loses pennies — total the raw values, then round once." ], [ "What are negative decimal places?", "Rounding to tens (−1), hundreds (−2): 145 → 150 → 100." ], [ "Should I round in calculations?", "No — keep raw values during math and round only the final result." ], [ "What is this used for?", "Money, grades, measurements, and any report where precision is controlled." ], [ "What is banker's rounding?", "Ties round to the nearest even digit, reducing cumulative bias in datasets." ], [ "Should I round during calculations?", "No — round only the final result; rounding each step loses precision." ], [ "Can I round to tens or hundreds?", "Yes — negative decimal places round to 10s, 100s, and beyond." ] ] }, { "slug": "royalty-calculator", "name": "Royalty Calculator", "canonical_url": "https://boringtoolskit.com/royalty-calculator/", "category": "Time & Work", "description": "Royalty calculator: earnings from sales at a royalty rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "rug-size-calculator", "name": "Rug Size Calculator", "canonical_url": "https://boringtoolskit.com/rug-size-calculator/", "category": "Construction & Measurement", "description": "Rug size calculator: recommended rug for a room.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "rule-of-72-calculator", "name": "Rule of 72 Calculator", "canonical_url": "https://boringtoolskit.com/rule-of-72-calculator/", "category": "Finance & Investing", "description": "Rule of 72 calculator: how many years to double your money at a given rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "salary-hourly-converter", "name": "Salary to Hourly Converter", "canonical_url": "https://boringtoolskit.com/salary-hourly-converter/", "category": "Time & Work", "description": "Convert annual salary to hourly, weekly, biweekly, and monthly equivalents.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/paycheck-calc/", "/time-card-calculator/", "/overtime-calculator/" ], "answer": "Convert annual salary to hourly, weekly, biweekly, and monthly equivalents.", "formula": "Hourly = annual salary ÷ (weeks worked × hours per week). Weekly = annual ÷ weeks. Biweekly = annual ÷ 26. Monthly = annual ÷ 12.", "example": "A $60,000 salary at 52 weeks × 40 hours = $28.85/hour.", "assumptions": [ "The salary is pre-tax gross.", "Weeks and hours reflect the real schedule.", "No bonus or benefit value is included." ], "sources": [ { "organization": "Wikipedia", "title": "Salary", "url": "https://en.wikipedia.org/wiki/Salary" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I convert salary to hourly?", "Divide the annual salary by (weeks worked × hours per week). $60,000 ÷ (52 × 40) = $28.85/hr." ], [ "How many hours are in a full-time year?", "52 weeks × 40 hours = 2,080 hours — the standard full-time baseline." ], [ "Does this include benefits?", "No — the converter is gross pay only. Benefits, bonuses, and equity add real value on top." ], [ "How do I compare a salary to a contract rate?", "Add 25–35% to the salaried equivalent — contractors pay their own taxes, insurance, and time off." ], [ "What if I work unpaid weeks?", "Use your actual weeks worked; unpaid leave lowers the real hourly rate." ], [ "What's the monthly equivalent?", "Annual ÷ 12: $60,000 ÷ 12 = $5,000/month." ], [ "Is salary or hourly better?", "Salary offers stability and benefits; hourly offers overtime and flexibility. Compare the effective hourly rate to decide." ] ] }, { "slug": "sales-commission-calculator", "name": "Sales Commission Calculator", "canonical_url": "https://boringtoolskit.com/sales-commission-calculator/", "category": "Time & Work", "description": "Sales commission calculator: earnings from a sale at a commission rate plus any base.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sales-tax-by-zip-calculator", "name": "Sales Tax by ZIP Code", "canonical_url": "https://boringtoolskit.com/sales-tax-by-zip-calculator/", "category": "Finance & Investing", "description": "Sales tax by ZIP code: see the candidate states, base rate, and local ceiling for any US ZIP.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sales-tax-calculator", "name": "Sales Tax Calculator", "canonical_url": "https://boringtoolskit.com/sales-tax-calculator/", "category": "Finance & Investing", "description": "Sales tax calculator: state base rate and total on a purchase.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sales-tax-vat-calculator", "name": "Sales Tax and VAT Calculator", "canonical_url": "https://boringtoolskit.com/sales-tax-vat-calculator/", "category": "Seller & Business", "description": "Sales tax calculator that adds or removes tax or VAT using your editable rate. Get the net amount, tax amount, and gross total instantly.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/paypal-fee-calculator/", "/discount-percent-off-calculator/", "/tip-bill-split-calculator/" ], "answer": "Sales tax calculator that adds or removes tax or VAT using your editable rate. Get the net amount, tax amount, and gross total instantly.", "formula": "Add tax: total = price × (1 + rate). Remove tax: pre-tax = total ÷ (1 + rate). The tool includes US state rates and EU/UK VAT references.", "example": "$100 at 8% sales tax: $108 total. €100 at 20% VAT: €20 tax included.", "assumptions": [ "The entered rate is current for the jurisdiction.", "One rate applies to the whole purchase.", "No exemptions or category variations apply." ], "sources": [ { "organization": "Wikipedia", "title": "Sales tax", "url": "https://en.wikipedia.org/wiki/Sales_tax" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate sales tax?", "Multiply the price by (1 + rate): $100 × 1.08 = $108 at 8%." ], [ "How do I remove tax from a total?", "Divide by (1 + rate): $108 ÷ 1.08 = $100 pre-tax." ], [ "What's the difference between sales tax and VAT?", "Sales tax (US) is added at checkout; VAT (EU/UK) is usually included in displayed prices." ], [ "What are current VAT rates?", "EU standard rates run 17–27% (Germany 19%, UK 20%) — the tool includes reference values." ], [ "Are all items taxed the same?", "No — many states exempt groceries or tax prepared food differently." ], [ "Why does my receipt differ?", "Local taxes (county/city) stack on state rates, and category rules vary." ], [ "How do I price with tax included?", "Use the remove direction to find the pre-tax base for a target total." ] ] }, { "slug": "sample-rate-bit-depth-calculator", "name": "Audio File Size Calculator", "canonical_url": "https://boringtoolskit.com/sample-rate-bit-depth-calculator/", "category": "Music & Audio", "description": "Audio file size calculator: uncompressed size from duration, sample rate, bit depth, and channels.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sample-size-calculator", "name": "Sample Size Calculator", "canonical_url": "https://boringtoolskit.com/sample-size-calculator/", "category": "Everyday Calculators", "description": "Determine the sample size needed for a survey or study at a given confidence and margin.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/confidence-interval-calculator/", "/percentile-calculator/", "/standard-deviation-calculator/" ], "answer": "Determine the sample size needed for a survey or study at a given confidence and margin.", "formula": "Required sample size n₀ = z² × p(1 − p) ÷ e², where z is the critical value for the confidence level (1.645/1.96/2.576), p is the expected proportion, and e is the margin of error. With a finite population, n = n₀ ÷ (1 + (n₀ − 1) ÷ N).", "example": "For 95% confidence (z = 1.96), a ±5% margin (e = 0.05), and p = 0.5: n₀ = 1.96² × 0.25 ÷ 0.0025 ≈ 384.16 → 385. For a population of 10,000, the finite correction gives about 370.", "assumptions": [ "Simple random sampling with independent observations.", "The proportion p is close to the expected value.", "Non-response and design effects are not included." ], "sources": [ { "organization": "NIST/SEMATECH", "title": "e-Handbook of Statistical Methods — Sample Sizes", "url": "https://www.itl.nist.gov/div898/handbook/prc/section2/prc252.htm" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How many people do I need to survey?", "It depends on the confidence level, margin of error, and expected proportion. For 95% confidence and ±5% margin, you need roughly 385 respondents (fewer with a small population)." ], [ "What is the formula?", "n₀ = z² × p(1 − p) ÷ e², where z is the z-value (1.96 for 95%), p the expected proportion, and e the margin of error. A finite population applies n = n₀ ÷ (1 + (n₀ − 1) ÷ N)." ], [ "Why is p = 0.5 conservative?", "p(1 − p) peaks at 0.25 when p = 0.5, giving the largest sample size. If you don't know the true proportion, using 0.5 guarantees enough precision." ], [ "What is a good margin of error?", "±5% is common for market research; ±3% is tighter and more expensive; ±10% is acceptable for quick directional reads. Smaller margins need bigger samples." ], [ "Does population size matter?", "Only for small populations. Above ~10,000–20,000 the finite-population correction barely changes the answer; below that it reduces the required n." ], [ "Does this include non-response?", "No — the answer is the number of completed responses. If you expect a 30% response rate, contact roughly 3.3× as many people." ], [ "Is random sampling assumed?", "Yes. Non-random samples (convenience, self-selected) aren't fixed by a bigger n — the formula only protects against sampling error." ] ] }, { "slug": "savings-calc", "name": "Savings Growth Calculator", "canonical_url": "https://boringtoolskit.com/savings-calc/", "category": "Finance & Investing", "description": "Savings calculator for monthly compound growth. Enter an amount, annual rate, and years to estimate your future savings value.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/savings-goal-calculator/", "/apy-calculator/", "/compound-interest/" ], "answer": "Savings calculator for monthly compound growth. Enter an amount, annual rate, and years to estimate your future savings value.", "formula": "Growth = principal × (1 + rate ÷ n)^(n × years), where n is the compounding frequency. The tool projects the balance over time.", "example": "$5,000 at 4% compounded monthly for 10 years grows to about $7,454.", "assumptions": [ "A constant APY over the period.", "No withdrawals.", "No additional contributions." ], "sources": [ { "organization": "Wikipedia", "title": "Compound interest", "url": "https://en.wikipedia.org/wiki/Compound_interest" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I project savings growth?", "Balance = principal × (1 + rate/n)^(n×years). $5,000 at 4% for 10 years ≈ $7,454." ], [ "What rate should I use?", "Your account's APY — high-yield savings accounts have offered 4–5%+ in recent cycles." ], [ "Does compounding frequency matter?", "Slightly — daily beats monthly beats annually, though the gap is small at typical APYs." ], [ "What is the real return after inflation?", "Subtract inflation: 4% APY − 3% inflation ≈ 1% real growth." ], [ "Can I add monthly deposits?", "Use the savings goal calculator — this tool models a lump sum." ], [ "Is the rate guaranteed?", "Only for fixed products like CDs; savings account APYs change with the market." ], [ "How do I compare banks?", "Compare APYs — the tool converts your balance and rate into the same growth projection." ], [ "How do I calculate savings growth?", "Principal × (1 + rate/periods)^(periods×years) plus compounded contributions." ], [ "What is a realistic savings rate?", "High-yield accounts pay 4–5%; the market pays more over long horizons with risk." ], [ "Does the compounding frequency matter?", "Slightly — monthly beats annual; daily beats monthly by a small margin." ], [ "How much do monthly contributions add?", "The calculator separates deposits from growth so you can see each." ] ] }, { "slug": "savings-goal-calculator", "name": "Savings Goal Calculator", "canonical_url": "https://boringtoolskit.com/savings-goal-calculator/", "category": "Finance & Investing", "description": "Calculate the monthly deposit needed to reach a savings goal with an editable APY and deadline.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/apy-calculator/", "/future-value-calculator/", "/emergency-fund-calculator/" ], "answer": "Calculate the monthly deposit needed to reach a savings goal with an editable APY and deadline.", "formula": "Monthly rate = (1 + APY)^(1/12) − 1; required deposit = remaining future value ÷ annuity future-value factor.", "example": "", "assumptions": [ "APY stays constant through the deadline.", "Deposits occur at the end of each month.", "Taxes, fees, rate tiers, and withdrawal restrictions are excluded." ], "sources": [ { "organization": "FDIC", "title": "National rates and rate caps", "url": "https://www.fdic.gov/resources/bankers/national-rates/" }, { "organization": "Investor.gov", "title": "Compound interest calculator", "url": "https://www.investor.gov/financial-tools-calculators/calculators/compound-interest-calculator" } ], "faqs": [ [ "How does a savings goal calculator help me reach my financial targets?", "A savings goal calculator shows you exactly how much you need to save each month to reach your target by a specific date, breaking down your goal into manageable steps." ], [ "Is my financial data safe since this is a no-signup tool?", "Yes, because this savings goal calculator runs entirely in your browser, no data is ever sent to a server or stored, ensuring your financial information remains completely private and secure." ], [ "Do I need to create an account to use the savings goal calculator?", "No, this is a no-signup tool, so you can calculate your savings goals instantly without providing an email or creating an account." ] ] }, { "slug": "scale-converter", "name": "Scale Converter", "canonical_url": "https://boringtoolskit.com/scale-converter/", "category": "Converters", "description": "Scale converter: real-world size from map or blueprint scale.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "scale-finder-calculator", "name": "Scale Finder Calculator", "canonical_url": "https://boringtoolskit.com/scale-finder-calculator/", "category": "Music & Audio", "description": "Find the notes in any major, minor, pentatonic, blues, or modal scale from a root.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/key-transposition-calculator/", "/frequency-to-note-calculator/", "/bpm-to-ms-calculator/" ], "answer": "Find the notes in any major, minor, pentatonic, blues, or modal scale from a root.", "formula": "Scale notes = root index + interval pattern (in semitones) mod 12, over the 12-note chromatic set. Supported patterns: major [0,2,4,5,7,9,11], minor [0,2,3,5,7,8,10], pentatonic major/minor, blues, dorian, mixolydian, lydian.", "example": "C major: C − D − E − F − G − A − B. A minor pentatonic: A − C − D − E − G.", "assumptions": [ "Root is a note name and scale is a supported pattern.", "Intervals are in semitones from the root.", "The output shows the notes in the selected pattern, not a chord or voicing." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "school-supply-budget-calculator", "name": "School Supply Budget Calculator", "canonical_url": "https://boringtoolskit.com/school-supply-budget-calculator/", "category": "School & Education", "description": "Estimate a back-to-school supply budget by grade level and number of children, including clothing, backpack extras, and estimated tax.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/rent-affordability-calculator/", "/percentage-calc/", "/sales-tax-vat-calculator/" ], "answer": "Estimate a back-to-school supply budget by grade level and number of children, including clothing, backpack extras, and estimated tax.", "formula": "Totals the estimated cost of school supplies and compares it against a budget, showing the surplus or shortfall.", "example": "Supplies totaling $42.50 against a $50 budget leaves $7.50 to spare.", "assumptions": [ "Prices are entered accurately.", "Sales tax is added by the user.", "The budget is the user's chosen cap." ], "sources": [ { "organization": "Wikipedia", "title": "Stationery", "url": "https://en.wikipedia.org/wiki/Stationery" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I budget for school supplies?", "List each item's cost, total them, and compare against your budget — the tool does the math." ], [ "What should I include?", "The school's supply list, plus tech, backpacks, and any required fees." ], [ "How can I cut costs?", "Buy generic brands, reuse last year's supplies, and shop sales/clearance." ], [ "Should I add sales tax?", "Yes — add tax to the total for an accurate budget." ], [ "How much do supplies typically cost?", "A full school list often runs $50–150+, depending on grade and requirements." ], [ "When should I buy?", "Early — prices rise and stock drops as the start of school approaches." ], [ "Is this just for kids?", "No — teachers and students can use the same tool for classroom budgets." ] ] }, { "slug": "scientific-notation-converter", "name": "Scientific Notation Converter", "canonical_url": "https://boringtoolskit.com/scientific-notation-converter/", "category": "Converters", "description": "Convert any number to and from scientific and engineering notation with significant-figure control.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "August 2026", "related_urls": [ "/roman-numeral-converter/", "/general-scientific-calculator/", "/currency-conv/" ], "answer": "Convert any number to and from scientific and engineering notation with significant-figure control.", "formula": "Scientific notation writes the number as a mantissa between 1 and 10 times a power of ten: value = mantissa × 10^exponent. The exponent is floor(log10(|value|)). Engineering notation restricts the exponent to a multiple of 3.", "example": "0.0000123 in scientific notation is 1.23 × 10^-5. 12,000 in engineering notation is 12 × 10^3.", "assumptions": [ "The value is written exactly to the requested significant figures.", "Exponent is derived from the absolute value; the sign is shown separately.", "Very large or small magnitudes are limited by JavaScript’s number range." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculation methodology and verification standard", "url": "/methodology/" } ], "faqs": [ [ "What is scientific notation?", "It writes a number as a mantissa (between 1 and 10) times a power of ten, like 1.23 × 10^-5. It makes very large and very small numbers easy to read and compare." ], [ "What is engineering notation?", "It is similar to scientific notation but restricts the exponent to a multiple of 3, so the mantissa falls between 1 and 1000 — useful in engineering and electronics." ], [ "How is scientific notation different from a normal decimal?", "It packs the same value into a scaled mantissa and an exponent. The calculator shows both the scientific form and the equivalent decimal value." ] ] }, { "slug": "screen-size-calculator", "name": "Screen Size Calculator", "canonical_url": "https://boringtoolskit.com/screen-size-calculator/", "category": "Converters", "description": "Screen size calculator: width and height from diagonal and aspect.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "self-employment-tax", "name": "1099 Income Tax Calculator", "canonical_url": "https://boringtoolskit.com/self-employment-tax/", "category": "Finance & Investing", "description": "Estimate federal self-employment tax and a quarterly planning amount for 1099 income.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/paycheck-calc/", "/freelance-hourly-rate-calculator/", "/paypal-fee-calculator/" ], "answer": "Estimate federal self-employment tax and a quarterly planning amount for 1099 income.", "formula": "Net earnings = profit × 92.35%. Self-employment tax = net × 15.3% (12.4% Social Security + 2.9% Medicare, with the Social Security wage cap). The tool also estimates federal income tax.", "example": "$50,000 profit: net earnings $46,175 → SE tax ≈ $7,065.", "assumptions": [ "US federal tax rules apply.", "The standard deduction is used.", "No state or city tax is modeled." ], "sources": [ { "organization": "Wikipedia", "title": "Self-employment tax", "url": "https://en.wikipedia.org/wiki/Self-employment_tax" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How much tax do self-employed people pay?", "15.3% SE tax on 92.35% of profit, plus income tax on the same profit — typically 25–35% total effective." ], [ "How is self-employment tax calculated?", "Profit × 92.35% × 15.3%: $50,000 → $7,065." ], [ "Why do I pay 15.3%?", "You cover both the employee (7.65%) and employer (7.65%) shares of Social Security and Medicare." ], [ "Can I deduct expenses?", "Yes — business expenses reduce profit before tax; that's why the tool asks for them." ], [ "Do I need to pay quarterly?", "Yes — most self-employed filers must pay estimated tax quarterly to avoid penalties." ], [ "What is the wage cap?", "The Social Security portion stops at a wage cap (~$168k in 2025); Medicare continues." ], [ "Is state tax included?", "No — the tool estimates federal. Add your state's income tax separately." ], [ "What is the self-employment tax rate?", "15.3% — 12.4% for Social Security and 2.9% for Medicare, applied to 92.35% of net profit." ], [ "Is self-employment tax the same as income tax?", "No — SE tax funds Social Security/Medicare; income tax is separate and paid on top." ], [ "When is the Social Security cap applied?", "The 12.4% portion stops at the annual wage base; income above it pays only Medicare portions." ], [ "Can I deduct half the self-employment tax?", "Yes — half is deductible on your income tax return." ] ] }, { "slug": "semester-gpa-calculator", "name": "Semester GPA Calculator", "canonical_url": "https://boringtoolskit.com/semester-gpa-calculator/", "category": "School & Education", "description": "Semester GPA calculator: grade point average from course credits and grade points.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "semicircle-calculator", "name": "Semicircle Calculator", "canonical_url": "https://boringtoolskit.com/semicircle-calculator/", "category": "Everyday Calculators", "description": "Semicircle calculator: area and arc length.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-27", "related_urls": [], "answer": "Semicircle calculator: area and arc length.", "formula": "Area = (π × r²)/2; perimeter = π × r + 2r (arc plus the straight diameter).", "example": "r = 4 m: area ≈ 25.13 m², perimeter ≈ 20.57 m.", "assumptions": [ "Standard geometric or arithmetic definitions apply.", "Inputs use the units you choose.", "Results are estimates, not professional advice." ], "sources": [ { "organization": "Standard mathematics definitions", "title": "Arithmetic and geometry formulas", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "sensitivity-specificity-calculator", "name": "Sensitivity Specificity Calculator", "canonical_url": "https://boringtoolskit.com/sensitivity-specificity-calculator/", "category": "Health", "description": "Sensitivity and specificity calculator: diagnostic test performance.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "septic-tank-size", "name": "Septic Tank Size Calculator", "canonical_url": "https://boringtoolskit.com/septic-tank-size/", "category": "Everyday Calculators", "description": "Estimate a septic tank size in gallons from the number of bedrooms and daily usage assumptions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/square-footage-calculator/", "/concrete-calculator/", "/property-area-calculator/" ], "answer": "Estimate a septic tank size in gallons from the number of bedrooms and daily usage assumptions.", "formula": "Daily flow = number of bedrooms (or occupants) × gallons per person per day. Sized tank = ceil(daily flow × safety factor). Common tank sizes: 750, 1,000, 1,250, 1,500 gallons.", "example": "A 3-bedroom home at 120 gal/person/day: daily flow = 360 gal. With a 1.5× safety factor: ≈ 540 gal, commonly rounded up to a 750-gallon tank.", "assumptions": [ "Daily flow is estimated from the number of bedrooms or occupants.", "The safety factor provides a buffer for retention and peak usage.", "Local code requirements govern the final size." ], "sources": [ { "organization": "Wikipedia", "title": "Septic tank", "url": "https://en.wikipedia.org/wiki/Septic_tank" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What size septic tank do I need?", "A common rule is 1,000 gallons for up to 3–4 bedrooms, scaling up with usage. The tool estimates from daily flow × a safety factor; local codes set the final requirement." ], [ "How is septic tank size calculated?", "Estimate daily wastewater flow (bedrooms × gallons per person per day), multiply by a safety factor, and round to a common tank size. 3 bedrooms × 120 gal × 1.5 ≈ 540 gal → commonly a 750 or 1,000 gal tank." ], [ "How many gallons per person per day?", "A typical planning figure is 100–150 gallons per person per day of indoor water use that flows to the septic system." ], [ "Why use bedrooms instead of occupants?", "Bedrooms are a stable proxy for a home's potential occupancy — codes use them because occupant counts change." ], [ "Can a tank be too big?", "Not usually, but oversizing wastes money. More importantly, a tank that's too small doesn't allow enough retention time for solids to settle." ], [ "What else affects sizing?", "Soil percolation, water table, lot size, and local health codes. A licensed designer's site evaluation is required for new systems." ], [ "Is this estimate code-compliant?", "It's a planning estimate. Your local permitting authority sets the exact requirement — always confirm before installing." ], [ "Why do codes use bedrooms instead of occupants?", "Bedrooms set the maximum potential occupancy, making the standard conservative and enforceable." ], [ "Does local code matter?", "Yes — counties and states can require larger minimums or different sizing methods." ], [ "Is a bigger tank always better?", "Generally safer for the drain field, but verify against local code and site conditions — and your budget." ] ] }, { "slug": "serial-dilution-calculator", "name": "Serial Dilution Calculator", "canonical_url": "https://boringtoolskit.com/serial-dilution-calculator/", "category": "Chemistry", "description": "Calculate serial dilution concentrations and cumulative dilution factors.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/dilution-calculator/", "/c1v1-c2v2-calculator/", "/molarity-calculator/" ], "answer": "Calculate serial dilution concentrations and cumulative dilution factors.", "formula": "Concentration at step i = stock × (1 ÷ dilution factor)^i.", "example": "Starting from a 10 M stock with a 10× dilution over 3 steps: step 1 = 1.0 M, step 2 = 0.1 M, step 3 = 0.01 M.", "assumptions": [ "Stock concentration, dilution factor (>1), and step count (1–20) are entered.", "Each step multiplies the previous concentration by 1 ÷ factor.", "The calculation assumes equal transfer and mixing volumes at each step." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "series-sum-calculator", "name": "Series Sum Calculator", "canonical_url": "https://boringtoolskit.com/series-sum-calculator/", "category": "Everyday Calculators", "description": "Arithmetic series sum calculator: a1 + (a1+d) + ...", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "severance-pay-calculator", "name": "Severance Pay Calculator", "canonical_url": "https://boringtoolskit.com/severance-pay-calculator/", "category": "Time & Work", "description": "Severance pay calculator: payout from weeks and salary.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "shift-differential-calculator", "name": "Shift Differential Calculator", "canonical_url": "https://boringtoolskit.com/shift-differential-calculator/", "category": "Time & Work", "description": "Estimate base pay, shift premium, overtime, and total gross shift pay.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/overtime-calculator/", "/time-card-calculator/", "/paycheck-calc/" ], "answer": "Estimate base pay, shift premium, overtime, and total gross shift pay.", "formula": "Shift premium = base pay × differential %. Total = (regular hours × rate × (1 + differential)) + overtime hours × rate × overtime multiplier.", "example": "40 hours at $20/hr with a 10% night differential: $800 × 1.10 = $880.", "assumptions": [ "The differential applies to regular hours.", "Overtime uses the base rate × multiplier.", "The premium reflects the employer's policy." ], "sources": [ { "organization": "Wikipedia", "title": "Shift work", "url": "https://en.wikipedia.org/wiki/Shift_work" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a shift differential?", "Extra pay for working undesirable shifts — typically 10–15% more for nights, weekends, or holidays." ], [ "How do I calculate it?", "Base pay × differential %: 40 hrs at $20 with 10% = $800 × 1.10 = $880." ], [ "Do I get the differential on overtime?", "Depends on the policy — many employers pay OT at the base rate multiplier without stacking the differential. Check your agreement." ], [ "Who gets shift differentials?", "Healthcare, manufacturing, security, and other 24/7 industries commonly pay them." ], [ "Is it the same as overtime?", "No — overtime is for hours beyond the threshold; a differential is a premium for the shift time itself." ], [ "What shifts qualify?", "Nights, weekends, and holidays — the exact definition is set by the employer." ], [ "How do I compare shifts?", "Run both schedules through the calculator — a 10% differential can outweigh a slightly higher base rate elsewhere." ], [ "Does the differential count toward overtime?", "For nonexempt workers, the premium generally applies to the adjusted rate — the calculator models it." ], [ "How much is typical?", "Common differentials run 5–15% for nights and higher for Sundays and holidays." ], [ "Is a differential worth the night shift?", "The pay math is clear; health, childcare, and commute costs are the rest of the decision." ] ] }, { "slug": "shiplap-calculator", "name": "Shiplap Calculator", "canonical_url": "https://boringtoolskit.com/shiplap-calculator/", "category": "Construction & Measurement", "description": "Shiplap calculator: boards needed for a wall with waste.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "shoe-size-conversion", "name": "Shoe Size Conversion", "canonical_url": "https://boringtoolskit.com/shoe-size-conversion/", "category": "Converters", "description": "Shoe size conversion: US men's and women's to UK, EU, and centimeters (approximate).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "shooting-percentage-calculator", "name": "Shooting Percentage Calculator", "canonical_url": "https://boringtoolskit.com/shooting-percentage-calculator/", "category": "Sports", "description": "Shooting percentage calculator: field-goal percentage from makes and attempts.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "shopify-fee-calculator", "name": "Shopify Fee Calculator", "canonical_url": "https://boringtoolskit.com/shopify-fee-calculator/", "category": "Seller & Business", "description": "Shopify fee calculator: monthly plan plus transaction fees on your sales volume.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "shopify-profit-calculator", "name": "Shopify Profit Calculator", "canonical_url": "https://boringtoolskit.com/shopify-profit-calculator/", "category": "Seller & Business", "description": "Free Shopify profit calculator: estimate payment processing, product, shipping, and ad costs plus net order profit and margin , with editable 2026 assumptions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/stripe-fee-calculator/", "/paypal-fee-calculator/", "/break-even-units-calculator/" ], "answer": "Free Shopify profit calculator: estimate payment processing, product, shipping, and ad costs plus net order profit and margin , with editable 2026 assumptions.", "formula": "Profit = revenue − payment fees (2.9% + $0.30 typical) − product costs − shipping − other costs.", "example": "$1,000 revenue with 2.9% + $0.30 payment fees and $400 in costs: profit ≈ $570.70.", "assumptions": [ "The payment rate reflects the store's plan.", "Product and shipping costs are entered.", "Subscription and apps are separate fixed costs." ], "sources": [ { "organization": "Wikipedia", "title": "Shopify", "url": "https://en.wikipedia.org/wiki/Shopify" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate Shopify profit?", "Revenue − payment fees − costs: $1,000 − $29.30 − $400 = $570.70." ], [ "What payment fees does Shopify charge?", "Shopify Payments runs ~2.4–2.9% + fixed, depending on plan; third-party gateways add a fee." ], [ "Is the subscription included?", "No — the monthly plan ($29+) is a fixed cost, not per-sale." ], [ "How do I price profitably?", "Start from profit, not revenue: subtract all fees and costs, then check the margin." ], [ "Does this include ads?", "No — marketing spend is separate. Use the break-even calculator to set ad budgets." ], [ "How do refunds affect it?", "They reverse the revenue and often keep the processing fee — subtract expected refund rates." ], [ "How do I compare payment providers?", "Run the same order through Stripe, PayPal, and Shopify Payments calculators and compare net." ], [ "What fees does Shopify charge?", "A monthly plan plus payment processing (2.9% + $0.30 typical), with extra fees for third-party gateways." ], [ "Does the plan tier matter?", "Yes — higher tiers lower transaction fees, which can pay for the plan at volume." ], [ "What is a healthy margin on Shopify?", "After all variable costs, 20–40% net margin is a common healthy range; below 10% leaves no room for errors." ] ] }, { "slug": "shutter-speed-stops-calculator", "name": "Shutter Speed Stops Calculator", "canonical_url": "https://boringtoolskit.com/shutter-speed-stops-calculator/", "category": "Photo & Video", "description": "Shutter speed stops calculator: find how many exposure stops (EV) differ between two shutter speeds.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "siding-calculator", "name": "Siding Calculator", "canonical_url": "https://boringtoolskit.com/siding-calculator/", "category": "Construction & Measurement", "description": "Siding calculator: squares of siding from wall area and waste allowance.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "significant-figures-calculator", "name": "Significant Figures Calculator", "canonical_url": "https://boringtoolskit.com/significant-figures-calculator/", "category": "Chemistry", "description": "Significant figures calculator: round a number to a given number of significant digits.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "simple-interest-calculator", "name": "Simple Interest Calculator", "canonical_url": "https://boringtoolskit.com/simple-interest-calculator/", "category": "Everyday Calculators", "description": "Calculate simple interest and total amount with interest using principal, annual rate, and time. Simple interest applies only to the original principal.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/compound-interest/", "/apy-calculator/", "/cagr-calculator/" ], "answer": "Calculate simple interest and total amount with interest using principal, annual rate, and time. Simple interest applies only to the original principal.", "formula": "Interest = principal × rate × time (I = P×r×t). Total = principal + interest. Interest per year = principal × rate.", "example": "$5,000 at 4% for 3 years: interest = $5,000 × 0.04 × 3 = $600; total = $5,600.", "assumptions": [ "The rate is annual and time is in years.", "Interest is not compounded.", "No payments are made during the term." ], "sources": [ { "organization": "Wikipedia", "title": "Interest", "url": "https://en.wikipedia.org/wiki/Interest" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is simple interest?", "Interest calculated only on the original principal: I = P × r × t. $5,000 at 4% for 3 years = $600." ], [ "What's the difference from compound interest?", "Compound interest earns interest on interest; simple interest doesn't. Over long periods the gap is large." ], [ "Where is simple interest used?", "Short-term loans, personal notes, bonds, and some consumer loans with flat-rate terms." ], [ "How do I calculate interest per year?", "Principal × rate: $5,000 × 4% = $200/year." ], [ "Is simple interest better for me?", "As a borrower, compounding costs more; simple interest is cheaper on long terms. As a saver, you want compounding." ], [ "Does this include payments?", "No — it assumes the principal is untouched for the whole term." ], [ "What about monthly rates?", "Convert: a monthly rate × 12 gives the annual rate, then use years." ] ] }, { "slug": "sit-up-test-calculator", "name": "Sit Up Test Calculator", "canonical_url": "https://boringtoolskit.com/sit-up-test-calculator/", "category": "Sports", "description": "Sit up test calculator: abdominal endurance rating.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sitemap-validate", "name": "Sitemap Validator", "canonical_url": "https://boringtoolskit.com/sitemap-validate/", "category": "Converters", "description": "Validate XML sitemap and robots basics.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/meta-tags/", "/keyword-density-calculator/", "/readability/" ], "answer": "Validate XML sitemap and robots basics.", "formula": "Parses the sitemap XML, checks it's well-formed (no parser errors), verifies the root element, and lists every <loc> URL. Invalid XML and missing URL elements are flagged.", "example": "A sitemap with 50 <url><loc> entries validates as well-formed XML and lists all 50 URLs for review.", "assumptions": [ "The sitemap uses standard sitemaps.org XML.", "The user pastes the complete XML document.", "Search-engine limits are checked separately." ], "sources": [ { "organization": "Wikipedia", "title": "Sitemaps", "url": "https://en.wikipedia.org/wiki/Sitemaps" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I validate a sitemap?", "Paste the XML — the tool checks that it parses cleanly and lists every URL in the <loc> elements." ], [ "What is a sitemap?", "An XML file listing the URLs on a site that you want search engines to crawl, with optional metadata like lastmod and priority." ], [ "What errors does it catch?", "Malformed XML (unclosed tags, bad escapes) and missing/empty loc elements." ], [ "Does valid XML mean my sitemap is accepted?", "No — search engines also enforce URL limits (50,000) and size limits (50 MB), and the URLs themselves must be live." ], [ "How often should I update it?", "After adding or removing significant pages. Search engines re-fetch sitemaps periodically." ], [ "Where do I submit it?", "Google Search Console and Bing Webmaster Tools both accept sitemap submissions." ], [ "What is the sitemap index?", "A sitemap that lists multiple sitemap files — used when a site has more than 50,000 URLs." ] ] }, { "slug": "skewness-calculator", "name": "Skewness Calculator", "canonical_url": "https://boringtoolskit.com/skewness-calculator/", "category": "Statistics", "description": "Skewness calculator: asymmetry of a sample distribution.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "ski-length-calculator", "name": "Ski Length Calculator", "canonical_url": "https://boringtoolskit.com/ski-length-calculator/", "category": "Sports", "description": "Ski length calculator: recommended ski length from height and style.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sleep-calculator", "name": "Sleep Cycle Calculator", "canonical_url": "https://boringtoolskit.com/sleep-calculator/", "category": "Health", "description": "Sleep cycle calculator: best bedtime to wake refreshed in 90-minute cycles.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sleep-cycle-calculator", "name": "Sleep Cycle Calculator", "canonical_url": "https://boringtoolskit.com/sleep-cycle-calculator/", "category": "Health", "description": "Sleep cycle calculator: find ideal bedtimes that end on a 90-minute sleep cycle for your wake time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sleep-debt-calculator", "name": "Sleep Debt Calculator", "canonical_url": "https://boringtoolskit.com/sleep-debt-calculator/", "category": "Health", "description": "Sleep debt calculator: accumulated lost sleep from target hours, actual hours, and days tracked.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sleep-length-calculator", "name": "Sleep Length Calculator", "canonical_url": "https://boringtoolskit.com/sleep-length-calculator/", "category": "Health", "description": "Sleep length calculator: hours and minutes from sleep cycles, plus when to wake.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "slogan-generator", "name": "Slogan Generator", "canonical_url": "https://boringtoolskit.com/slogan-generator/", "category": "Generators", "description": "Generate brand slogan and tagline ideas from your business, benefit, and industry.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "August 2026", "related_urls": [ "/business-name-generator/", "/product-description-generator/", "/quote-estimate-generator/" ], "answer": "Generate brand slogan and tagline ideas from your business, benefit, and industry.", "formula": "Slogans are built from pattern templates that swap in your business, key benefit, and industry. The templates are rotated and de-duplicated to return a fresh set each time.", "example": "Enter your brand, benefit, and industry to get slogans like 'Brewhaus: save time without the wait.'", "assumptions": [ "Generated output is a starting point, not final professional copy.", "Nothing you type leaves your browser.", "Results vary on each run because selection is random." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculation methodology and verification standard", "url": "/methodology/" } ], "faqs": [ [ "Are the slogans unique?", "They're built from common template patterns, so they may resemble existing slogans. Search before you commit." ], [ "Can I edit the result?", "Yes — treat the output as a starting point and refine it to match your brand voice." ], [ "Do I need an account?", "No. Everything runs locally in your browser and nothing is stored." ] ] }, { "slug": "slope-calculator", "name": "Slope Calculator", "canonical_url": "https://boringtoolskit.com/slope-calculator/", "category": "Construction & Measurement", "description": "Slope calculator: degrees, percent grade, and ratio from rise and run.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "slope-intercept-calculator", "name": "Slope Intercept Calculator", "canonical_url": "https://boringtoolskit.com/slope-intercept-calculator/", "category": "Everyday Calculators", "description": "Slope intercept calculator: y = mx + b from two points.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "slug-generator", "name": "Slug Generator", "canonical_url": "https://boringtoolskit.com/slug-generator/", "category": "Text & Developer Tools", "description": "Turn any headline or phrase into a clean, URL-friendly slug instantly in your browser. SEO-ready output with a one-click copy.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "smoker-time-calculator", "name": "Smoker Time Calculator", "canonical_url": "https://boringtoolskit.com/smoker-time-calculator/", "category": "Food & Cooking", "description": "Smoker time calculator: smoking time by cut at 225°F.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "soccer-speed-calculator", "name": "Soccer Speed Calculator", "canonical_url": "https://boringtoolskit.com/soccer-speed-calculator/", "category": "Sports", "description": "Soccer speed calculator: sprint speed from distance and time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "social-media-earnings-calculator", "name": "Social Media Earnings Calculator", "canonical_url": "https://boringtoolskit.com/social-media-earnings-calculator/", "category": "Social Media", "description": "Estimate potential income from social platforms and sponsorship value.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/youtube-revenue-calculator/", "/tiktok-money-calculator/", "/follower-growth-calculator/" ], "answer": "Estimate potential income from social platforms and sponsorship value.", "formula": "Total earnings = monthly revenue × months. Annual equivalent = monthly revenue × 12.", "example": "$1,500/month for 18 months: total = $27,000, or $18,000/year on an annual basis.", "assumptions": [ "Monthly revenue is a steady average across the period.", "Earnings are gross before tax and platform deductions.", "Revenue is not projected to grow or shrink across the months." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "social-media-engagement-rate-calculator", "name": "Social Media Engagement Rate Calculator", "canonical_url": "https://boringtoolskit.com/social-media-engagement-rate-calculator/", "category": "Everyday Calculators", "description": "Calculate engagement rate from likes, comments, shares, and reach or followers, and compare against typical benchmarks.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/cpm-calculator/", "/marketplace-ad-break-even-calculator/", "/video-watch-time-calculator/" ], "answer": "Calculate engagement rate from likes, comments, shares, and reach or followers, and compare against typical benchmarks.", "formula": "Engagement rate = (likes + comments + shares) ÷ followers × 100, or ÷ reach × 100 when reach is the denominator.", "example": "500 interactions on a post reaching 10,000 followers: engagement rate = 5.0%.", "assumptions": [ "Interactions are likes + comments + shares.", "The denominator is followers or reach as chosen.", "Rates are compared within the same platform." ], "sources": [ { "organization": "Wikipedia", "title": "Social media", "url": "https://en.wikipedia.org/wiki/Social_media" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate engagement rate?", "(Likes + comments + shares) ÷ followers × 100: 500 ÷ 10,000 = 5%." ], [ "What is a good engagement rate?", "1–3% is average on most platforms; 5%+ is strong; below 1% signals weak resonance." ], [ "Followers or reach?", "Followers is the standard benchmark; reach gives a higher, more real-time number. Be consistent." ], [ "Does every platform count the same?", "No — saves and views are weighted differently across platforms." ], [ "Why is my rate dropping?", "Algorithm changes, audience fatigue, or less resonant content — check which posts still perform." ], [ "How do I improve it?", "Post content your audience actually saves and shares, ask questions, and post when they're active." ], [ "Can I compare accounts?", "Yes — the rate normalizes for size, so it's the fairest cross-account comparison." ] ] }, { "slug": "social-security-break-even-calculator", "name": "Social Security Break Even Calculator", "canonical_url": "https://boringtoolskit.com/social-security-break-even-calculator/", "category": "Finance & Investing", "description": "Social security break-even calculator: at what age claiming later pays off vs claiming at 62.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "social-security-tax-calculator", "name": "Social Security Tax Calculator", "canonical_url": "https://boringtoolskit.com/social-security-tax-calculator/", "category": "Finance & Investing", "description": "Social Security tax calculator: how much of your benefit is taxable (50% or 85% rule).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sodium-calculator", "name": "Sodium Calculator", "canonical_url": "https://boringtoolskit.com/sodium-calculator/", "category": "Health", "description": "Sodium calculator: mg sodium to salt grams and daily value.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "solar-panel-savings-calculator", "name": "Solar Panel Savings Calculator", "canonical_url": "https://boringtoolskit.com/solar-panel-savings-calculator/", "category": "Energy & Electrical", "description": "Solar panel savings calculator: annual savings and payback period from system size, cost, and utility rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sonotube-concrete-column", "name": "Sonotube Concrete Calculator", "canonical_url": "https://boringtoolskit.com/sonotube-concrete-column/", "category": "Everyday Calculators", "description": "Estimate concrete for a round sonotube column in cubic feet, cubic yards, and 60/80 lb bags.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/concrete-calculator/", "/concrete-cost-per-square-foot/", "/mulch-soil-calculator/" ], "answer": "Estimate concrete for a round sonotube column in cubic feet, cubic yards, and 60/80 lb bags.", "formula": "Radius r = (diameter ÷ 2) ÷ 12 (ft). Volume per tube = π × r² × height. Total = volume per tube × number of tubes. Cubic yards = total ÷ 27. Order = cubic yards × (1 + waste%). Bags: 60 lb ≈ 0.45 cu ft each; 80 lb ≈ 0.6 cu ft.", "example": "Four 12 in diameter × 4 ft columns: r = 0.5 ft, volume per tube ≈ 3.14 cu ft, total ≈ 12.57 cu ft ≈ 0.465 cu yd. With 10% waste: ≈ 0.51 cu yd, or about 31 sixty-pound bags.", "assumptions": [ "Tubes are uniform cylinders filled to the top.", "Bags are 60 lb (0.45 cu ft) or 80 lb (0.6 cu ft).", "Waste covers spillage and uneven tops." ], "sources": [ { "organization": "Quikrete", "title": "Concrete Calculators", "url": "https://www.quikrete.com/calculator/main.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How much concrete is in a sonotube?", "Use the cylinder formula: π × radius² × height. A 12 in diameter × 4 ft tube holds about 3.14 cu ft." ], [ "What is a sonotube?", "A brand of cylindrical cardboard form used to pour round concrete columns, footings, and piers." ], [ "How do I convert diameter to radius in feet?", "Divide the diameter by 2 to get the radius in inches, then divide by 12: 12 in diameter → 0.5 ft radius." ], [ "How many bags of concrete do I need per column?", "Divide the volume by the bag yield: a 60 lb bag makes about 0.45 cu ft, an 80 lb bag about 0.6 cu ft. Four 12×4 ft columns need about 31 sixty-pound bags with waste." ], [ "Should I order ready-mix or bags?", "Bags work for small jobs and tight access; ready-mix is better for volume. Compare cost and delivery minimums." ], [ "Does this include rebar?", "No — rebar or reinforcement is planned separately based on the structural requirements." ], [ "What if my column flares at the base?", "A bell footing adds significant volume. Calculate the footing separately and add it to the column volume." ], [ "How much concrete for a sonotube?", "π × radius² × height per column; convert cubic feet to bags using the mix yield." ], [ "How many bags of concrete per tube?", "A 12×4-ft tube ≈ 3.14 cu ft — about 7 sixty-pound bags." ], [ "Do I include the buried portion?", "Yes — the tube below grade is part of the pour and the volume." ], [ "How much extra should I buy?", "About 10% for spill, flare, and over-dig." ] ] }, { "slug": "soup-scale-calculator", "name": "Soup Scale Calculator", "canonical_url": "https://boringtoolskit.com/soup-scale-calculator/", "category": "Food & Cooking", "description": "Soup scale calculator: scale a soup or stock recipe from a base yield to a target yield.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sourdough-hydration-calculator", "name": "Sourdough Hydration Calculator", "canonical_url": "https://boringtoolskit.com/sourdough-hydration-calculator/", "category": "Food & Cooking", "description": "Sourdough hydration calculator: dough hydration percentage.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sous-vide-time-calculator", "name": "Sous Vide Time Calculator", "canonical_url": "https://boringtoolskit.com/sous-vide-time-calculator/", "category": "Food & Cooking", "description": "Sous vide time calculator: cooking time by cut and thickness.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "speaking-time-calculator", "name": "Speaking Time Calculator", "canonical_url": "https://boringtoolskit.com/speaking-time-calculator/", "category": "School & Education", "description": "Speaking time calculator: how long a script takes to say.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "speed-converter", "name": "Speed Converter", "canonical_url": "https://boringtoolskit.com/speed-converter/", "category": "Converters", "description": "Speed converter: mph, km/h, m/s, ft/s, and knots.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "speed-distance-time-calculator", "name": "Speed Distance Time Calculator", "canonical_url": "https://boringtoolskit.com/speed-distance-time-calculator/", "category": "Physics", "description": "Speed distance time calculator: solve for the missing value (speed, distance, or time).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sphere-volume-calculator", "name": "Sphere Volume Calculator", "canonical_url": "https://boringtoolskit.com/sphere-volume-calculator/", "category": "Everyday Calculators", "description": "Sphere volume calculator: volume and surface area from radius.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-27", "related_urls": [], "answer": "Sphere volume calculator: volume and surface area from radius.", "formula": "Volume = (4/3) × π × r³; surface area = 4 × π × r².", "example": "r = 3 m: volume ≈ 113.10 m³.", "assumptions": [ "Standard geometric or arithmetic definitions apply.", "Inputs use the units you choose.", "Results are estimates, not professional advice." ], "sources": [ { "organization": "Standard mathematics definitions", "title": "Arithmetic and geometry formulas", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "sprinkler-heads-calculator", "name": "Sprinkler Heads Calculator", "canonical_url": "https://boringtoolskit.com/sprinkler-heads-calculator/", "category": "Construction & Measurement", "description": "Sprinkler heads calculator: heads needed for a lawn area.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sprint-capacity-calculator", "name": "Sprint Capacity Calculator", "canonical_url": "https://boringtoolskit.com/sprint-capacity-calculator/", "category": "Time & Work", "description": "Sprint capacity calculator: team capacity in person-days and hours.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "square-fee-calculator", "name": "Square Fee Calculator", "canonical_url": "https://boringtoolskit.com/square-fee-calculator/", "category": "Seller & Business", "description": "Square fee calculator: the 2.6% + 10\\u00a2 card-present fee and your net.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "square-feet-to-linear-feet", "name": "Square Feet to Linear Feet Calculator", "canonical_url": "https://boringtoolskit.com/square-feet-to-linear-feet/", "category": "Construction & Measurement", "description": "Convert square feet or square yards to linear material length using the required material width.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/board-foot-calculator/", "/square-footage-calculator/", "/flooring-calculator/" ], "answer": "Convert square feet or square yards to linear material length using the required material width.", "formula": "Linear feet = area ÷ material width (converted to feet). It converts a square-foot purchase into the linear length of a roll, board, or strip.", "example": "100 sq ft of 2-foot-wide material = 50 linear feet.", "assumptions": [ "The material is a uniform strip of the entered width.", "Area and width use convertible units.", "Waste is added by the user (~10%)." ], "sources": [ { "organization": "Wikipedia", "title": "Board foot", "url": "https://en.wikipedia.org/wiki/Board_foot" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I convert square feet to linear feet?", "Divide the area by the material width: 100 sq ft ÷ 2 ft = 50 linear ft." ], [ "What is a linear foot?", "A 1-foot length of material regardless of width — how lumber, fabric, and flooring are sold." ], [ "Does the width matter?", "Yes — the conversion depends entirely on the material's width." ], [ "What about carpet rolls?", "Carpet comes in 12-ft rolls typically: 100 sq ft ÷ 12 = 8.3 linear ft." ], [ "Should I add waste?", "Yes — 10% covers cuts, seams, and mistakes." ], [ "Can I convert back?", "Yes — linear ft × width = area." ], [ "Is this the same as board feet?", "No — board feet measure lumber volume (thickness × width × length); this is area-to-length." ] ] }, { "slug": "square-footage-calculator", "name": "Square Footage Calculator", "canonical_url": "https://boringtoolskit.com/square-footage-calculator/", "category": "Construction & Measurement", "description": "Calculate square footage for rooms and projects with waste allowance, square-yard/meter/acre conversions, and optional material cost estimate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/flooring-calculator/", "/tile-calculator/", "/property-area-calculator/" ], "answer": "Calculate square footage for rooms and projects with waste allowance, square-yard/meter/acre conversions, and optional material cost estimate.", "formula": "Area 1 = length1 × width1; Area 2 = length2 × width2; base total = area1 + area2. Total with waste = base × (1 + waste%). Conversions: sq yd = total ÷ 9, sq m = total × 0.09290304, acres = total ÷ 43,560. Estimated material cost = total × price per unit.", "example": "A 12×10 ft area (120 sq ft) plus an 8×6 ft area (48 sq ft) = 168 sq ft. With 10% waste: 184.8 sq ft ≈ 20.5 sq yd, 17.2 sq m, or 0.0042 acres. At $5/sq ft, materials ≈ $924.", "assumptions": [ "Up to two rectangular areas are entered.", "Waste is a percentage of the base total.", "Conversions use standard international definitions." ], "sources": [ { "organization": "CalculatorSoup", "title": "Square Footage Calculator", "url": "https://www.calculatorsoup.com/calculators/construction/square-footage-calculator.php" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate square footage?", "Multiply length by width for each space, then add them. A 12×10 ft room is 120 sq ft; two such rooms total 240 sq ft." ], [ "How many square feet in a square yard?", "9 (3 ft × 3 ft). Flooring is sometimes sold by the square yard." ], [ "How many square feet in an acre?", "43,560. Divide square feet by 43,560 to get acres — useful for land parcels." ], [ "How do I convert square feet to square meters?", "Multiply by 0.09290304. 184.8 sq ft ≈ 17.2 sq m." ], [ "Why add waste?", "Materials like flooring and tile need extra for cuts and mistakes. 10% is standard; diagonal layouts need more." ], [ "Does this work for triangular or round rooms?", "No — split irregular shapes into rectangles, or use the shape-specific calculator for circles and triangles." ], [ "What is the price-per-unit for?", "Estimating material cost: total square feet × price per square foot (or per square yard if you enter that unit)." ] ] }, { "slug": "stair-calculator", "name": "Stair Calculator", "canonical_url": "https://boringtoolskit.com/stair-calculator/", "category": "Construction & Measurement", "description": "Estimate stair riser count, actual riser height, treads, total run, and stringer length.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/decking-calculator/", "/board-foot-calculator/", "/square-feet-to-linear-feet/" ], "answer": "Estimate stair riser count, actual riser height, treads, total run, and stringer length.", "formula": "Risers = ceiling(total rise ÷ target riser); actual riser = total rise ÷ risers; treads = risers − 1; stringer slope = √(rise² + run²).", "example": "", "assumptions": [ "The stair is a straight flight with equal risers.", "The target is used to choose a count; local code controls maximum riser and minimum tread.", "Structural sizing, nosing, landings, headroom, guards, and handrails are excluded." ], "sources": [ { "organization": "International Code Council", "title": "Residential code information", "url": "https://www.iccsafe.org/products-and-services/i-codes/2024-i-codes/irc/" }, { "organization": "OSHA", "title": "Stairways and ladders guidance", "url": "https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.1052" } ], "faqs": [ [ "Do I need to create an account or sign up to use the stair calculator?", "No. The stair calculator is entirely no-signup and runs directly in your browser — nothing is saved or uploaded." ], [ "Is my data safe when using the stair calculator?", "Yes. All calculations happen locally on your device in the browser. No personal data or input values are stored, transmitted, or collected." ], [ "What measurements does the stair calculator use to generate stair dimensions?", "The stair calculator uses your total rise (floor-to-floor height), desired tread depth, and riser height to compute step count, run length, and stringer angles for safe, code-compliant stairs." ] ] }, { "slug": "staircase-calculator", "name": "Staircase Calculator", "canonical_url": "https://boringtoolskit.com/staircase-calculator/", "category": "Construction & Measurement", "description": "Staircase calculator: number of treads and total run from floor height and chosen rise.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "standard-deviation-calculator", "name": "Standard Deviation Calculator", "canonical_url": "https://boringtoolskit.com/standard-deviation-calculator/", "category": "Everyday Calculators", "description": "Calculate the sample or population standard deviation, variance, mean, and margin of error for any set of numbers.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/statistics-calculator/", "/variance-calculator/", "/z-score-calculator/" ], "answer": "Calculate the sample or population standard deviation, variance, mean, and margin of error for any set of numbers.", "formula": "Standard deviation = √(Σ(xᵢ − mean)² ÷ n) for a population, or ÷ (n − 1) for a sample. It measures how spread out values are around the mean.", "example": "For [2, 4, 4, 4, 5, 5, 7, 9]: population SD ≈ 2.00, sample SD ≈ 2.14.", "assumptions": [ "At least two numbers are provided.", "The mode (population/sample) matches the context.", "Values are numeric." ], "sources": [ { "organization": "Wikipedia", "title": "Standard deviation", "url": "https://en.wikipedia.org/wiki/Standard_deviation" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is standard deviation?", "The typical distance of values from the mean — how spread out the data is." ], [ "How is it calculated?", "Square each deviation from the mean, average (n or n−1), and take the square root." ], [ "Population or sample?", "Sample (n−1) when your data estimates a larger population — the usual research case." ], [ "What does ±1 SD mean?", "About 68% of values in a normal distribution fall within one standard deviation of the mean." ], [ "How is it different from variance?", "SD is the square root — in the original units, so easier to interpret." ], [ "What is it used for?", "Risk (finance), process consistency (quality), and statistical inference." ], [ "Why is my SD affected by outliers?", "Squaring the deviations gives extreme values extra weight." ] ] }, { "slug": "standard-error-calculator", "name": "Standard Error Calculator", "canonical_url": "https://boringtoolskit.com/standard-error-calculator/", "category": "Everyday Calculators", "description": "Calculate the standard error of the mean (SEM). Enter sample standard deviation and size to measure how precise the sample mean is.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/variance-calculator/", "/statistics-calculator/", "/coefficient-of-variation-calculator/" ], "answer": "Calculate the standard error of the mean (SEM). Enter sample standard deviation and size to measure how precise the sample mean is.", "formula": "Standard error of the mean (SEM) = standard deviation ÷ √sample size. 95% margin = ±1.96 × SEM.", "example": "With a standard deviation of 12 and a sample size of 36: SEM = 12 ÷ √36 = 12 ÷ 6 = 2.0. The 95% margin is ±1.96 × 2.0 = ±3.92.", "assumptions": [ "Sample size must be ≥1 and standard deviation ≥0.", "The 95% margin assumes an approximately normal sampling distribution.", "SEM measures how far the sample mean is likely to fall from the true mean." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "NIST/SEMATECH e-Handbook of Statistical Methods", "url": "https://www.itl.nist.gov/div898/handbook/" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "standing-desk-calculator", "name": "Standing Desk Calculator", "canonical_url": "https://boringtoolskit.com/standing-desk-calculator/", "category": "Time & Work", "description": "Standing desk calculator: desk, chair, and monitor heights from your height.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "star-magnitude-calculator", "name": "Star Magnitude Calculator", "canonical_url": "https://boringtoolskit.com/star-magnitude-calculator/", "category": "Astronomy", "description": "Star magnitude calculator: brightness ratio between two apparent magnitudes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "statistics-calculator", "name": "Statistics Calculator", "canonical_url": "https://boringtoolskit.com/statistics-calculator/", "category": "Everyday Calculators", "description": "Compute descriptive statistics for a sample or population: mean, median, mode, range, sum, count, standard deviation, variance, and geometric mean.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/variance-calculator/", "/standard-error-calculator/", "/quartile-calculator/" ], "answer": "Compute descriptive statistics for a sample or population: mean, median, mode, range, sum, count, standard deviation, variance, and geometric mean.", "formula": "Mean = Σx ÷ n. Sample variance s² = Σ(x − mean)² ÷ (n − 1); population σ² = Σ(x − mean)² ÷ n. Standard deviation = √variance. Median is the middle value (or mean of the two middle values for even n). Mode is the most frequent value.", "example": "For the data set 4, 8, 6, 5, 3: mean = 26 ÷ 5 = 5.2. Sample variance = (1.44 + 7.84 + 0.64 + 0.04 + 4.84) ÷ 4 = 3.7, so sample standard deviation ≈ 1.92. Median = 5, and with all values unique there is no mode.", "assumptions": [ "The tool splits the input on commas, whitespace, or semicolons and treats each number as one observation.", "Sample mode uses n−1 for the denominator, population uses n.", "Geometric mean is shown only for data sets of positive values." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "NIST/SEMATECH e-Handbook of Statistical Methods", "url": "https://www.itl.nist.gov/div898/handbook/" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "steak-doneness-calculator", "name": "Steak Doneness Calculator", "canonical_url": "https://boringtoolskit.com/steak-doneness-calculator/", "category": "Food & Cooking", "description": "Steak doneness calculator: internal temperature guide.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "stellar-temperature-calculator", "name": "Stellar Temperature Calculator", "canonical_url": "https://boringtoolskit.com/stellar-temperature-calculator/", "category": "Astronomy", "description": "Stellar temperature calculator: blackbody temperature from peak wavelength (Wien's law).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "steps-to-miles-calculator", "name": "Steps to Miles Calculator", "canonical_url": "https://boringtoolskit.com/steps-to-miles-calculator/", "category": "Health", "description": "Steps to miles calculator: distance walked and calories burned from step count.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "stock-average-cost-calculator", "name": "Average Share Cost Calculator", "canonical_url": "https://boringtoolskit.com/stock-average-cost-calculator/", "category": "Finance & Investing", "description": "Calculate weighted average share cost, total shares, cost basis, and unrealized gain.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/stock-calc/", "/crypto-calc/", "/dca-investment-calculator/" ], "answer": "Calculate weighted average share cost, total shares, cost basis, and unrealized gain.", "formula": "Average cost per share = (shares₁ × price₁ + shares₂ × price₂ + …) ÷ total shares. It tracks the blended basis after multiple buys.", "example": "100 shares at $50 plus 100 shares at $60: average cost = $55 per share.", "assumptions": [ "No splits, dividends, or fees are modeled.", "All purchases are of the same stock.", "Simple average-cost basis applies." ], "sources": [ { "organization": "Wikipedia", "title": "Average cost method", "url": "https://en.wikipedia.org/wiki/Average_cost_method" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate average cost per share?", "Total cost ÷ total shares: (100×50 + 100×60) ÷ 200 = $55." ], [ "Why does average cost matter?", "It's your blended basis — what you compare against the selling price for profit and taxes." ], [ "Do fees affect it?", "Yes — add trading fees to the cost for an accurate basis." ], [ "What about splits and dividends?", "Splits divide the basis per share; reinvested dividends add shares. The tool models simple buys." ], [ "Is this the same as DCA?", "Related — DCA is the strategy of buying regularly; average cost is the resulting basis." ], [ "Should I sell the highest-cost or lowest-cost lots?", "Tax-wise it depends: selling high-cost lots realizes less gain (or a loss) now; low-cost lots defer more gain. Check your broker's lot selection." ], [ "Can I use it for crypto?", "Yes — the same math applies to coin purchases at different prices." ], [ "How do I calculate my average stock cost?", "Divide total dollars invested (including fees) by total shares owned — each purchase updates both numbers." ], [ "Do reinvested dividends count?", "Yes — they buy more shares, so they raise the share count and adjust the average cost." ], [ "Is average cost the same as break-even?", "For a full position, yes: selling above average cost realizes a gain; below, a loss." ], [ "Can I use average cost for taxes?", "Yes — it is an allowed cost-basis method, common for mutual funds; check your broker's default for stocks." ] ] }, { "slug": "stock-calc", "name": "Share Profit Calculator", "canonical_url": "https://boringtoolskit.com/stock-calc/", "category": "Finance & Investing", "description": "Calculate stock profit, ROI, and per-share returns.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/crypto-calc/", "/investment-return-calculator/", "/percentage-calc/" ], "answer": "Calculate stock profit, ROI, and per-share returns.", "formula": "Profit = (sell price − buy price) × shares − buy fees − sell fees. Return on investment = profit ÷ (buy price × shares + buy fee) × 100. Breakeven price = buy price + fees ÷ shares.", "example": "100 shares bought at $50 and sold at $60 with $10 in each fee: profit = $1,000 − $20 = $980, ROI ≈ 19.6%.", "assumptions": [ "No dividends or distributions during the holding period.", "Fees are fixed per trade as entered.", "Simple, non-leveraged position." ], "sources": [ { "organization": "Wikipedia", "title": "Capital gain", "url": "https://en.wikipedia.org/wiki/Capital_gain" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate stock profit?", "Profit = (sell − buy) × shares − fees. 100 shares from $50 to $60 with $20 in fees = $980." ], [ "What is ROI?", "Return on investment: profit ÷ cost basis × 100. $980 ÷ $5,010 ≈ 19.6%." ], [ "What is the breakeven price?", "The price at which you recover your cost including fees — anything above it is profit." ], [ "Do I owe taxes on gains?", "Yes — capital gains tax applies, at lower rates for holdings over a year in most jurisdictions. Check local rules." ], [ "What are hidden costs?", "Bid-ask spread and slippage — the difference between the quoted price and what you actually get." ], [ "Does this include dividends?", "No — dividends are separate income. Add them to total return if you track them." ], [ "How do I compare to an index?", "Use ROI and compare it to the benchmark's return over the same period — that tells you if you beat the market." ], [ "How do I calculate profit on a stock trade?", "Shares × (sale price − cost per share) − fees = net profit." ], [ "Do fees really matter?", "Yes — fees add to cost basis and subtract from proceeds; on small trades they are a meaningful percentage." ], [ "What is cost basis?", "The total amount you paid for the shares, including commissions — the reference point for gains and losses." ], [ "Is this a capital gains calculator?", "It shows the gain/loss in dollars; the tax rate depends on your holding period and bracket." ] ] }, { "slug": "stock-return-calculator", "name": "Stock Return Calculator", "canonical_url": "https://boringtoolskit.com/stock-return-calculator/", "category": "Finance & Investing", "description": "Stock return calculator: total return including dividends.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "stoichiometry-calculator", "name": "Stoichiometry Calculator", "canonical_url": "https://boringtoolskit.com/stoichiometry-calculator/", "category": "Chemistry", "description": "Calculate reactant and product quantities from balanced equation ratios.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/limiting-reagent-calculator/", "/percent-yield-calculator/", "/molar-mass-calculator/" ], "answer": "Calculate reactant and product quantities from balanced equation ratios.", "formula": "Moles of reactant = mass ÷ molar mass. Moles of product = reactant moles × (product coefficient ÷ reactant coefficient). Product mass = product moles × product molar mass.", "example": "For 44 g of a reactant with molar mass 44 g/mol, coefficient 1, and product molar mass 18 g/mol with coefficient 2: reactant moles = 1.0, product moles = 2.0, product mass = 2.0 × 18 = 36 g.", "assumptions": [ "Reactant mass, both molar masses, and both coefficients are required.", "Molar masses must be positive and coefficients non-zero.", "The calculation uses the balanced-equation mole ratio." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "stone-pounds-converter", "name": "Stone to Pounds Converter", "canonical_url": "https://boringtoolskit.com/stone-pounds-converter/", "category": "Converters", "description": "Stone to pounds converter: stone, pounds, kg.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "stopping-distance-calculator", "name": "Stopping Distance Calculator", "canonical_url": "https://boringtoolskit.com/stopping-distance-calculator/", "category": "Vehicles", "description": "Stopping distance calculator: reaction plus braking distance by speed.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "stopwatch", "name": "Stopwatch", "canonical_url": "https://boringtoolskit.com/stopwatch/", "category": "Time & Work", "description": "Time events with lap tracking — start, stop, and record laps to hundredths of a second. Free, private, runs locally in your browser.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/countdown-timer/", "/pomodoro-timer/", "/typing-test/" ], "answer": "Time events with lap tracking — start, stop, and record laps to hundredths of a second. Free, private, runs locally in your browser.", "formula": "Elapsed time = current time − start time, measured in milliseconds and displayed as minutes:seconds.hundredths. Lap times record the interval between lap presses.", "example": "Starting at 0:00 and pressing lap at 1:23.45 records lap 1 at 1:23.45; the next lap measures from there.", "assumptions": [ "The browser tab remains active.", "Millisecond-level timing from the system clock is sufficient.", "Laps are recorded in sequence." ], "sources": [ { "organization": "Wikipedia", "title": "Stopwatch", "url": "https://en.wikipedia.org/wiki/Stopwatch" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How does the stopwatch work?", "It measures elapsed time from start to stop and records laps between presses, displayed to hundredths of a second." ], [ "What are laps?", "Interval times recorded between lap presses — so you can compare splits within a single run." ], [ "How accurate is it?", "Accurate to hundredths of a second for normal use, based on the system clock. Not a certified instrument for official timing." ], [ "Why might it drift?", "Background-tab throttling can affect browser timers — keep the tab visible for precise timing." ], [ "Can I use it for workouts?", "Yes — lap intervals are ideal for circuits and interval training." ], [ "What's the difference from a countdown?", "A countdown runs from a set time down to zero; a stopwatch runs up from zero." ], [ "How do I reset?", "Press reset after stopping — the display returns to zero for the next run." ] ] }, { "slug": "story-points-to-hours-calculator", "name": "Story Points to Hours Calculator", "canonical_url": "https://boringtoolskit.com/story-points-to-hours-calculator/", "category": "Time & Work", "description": "Story points to hours calculator: agile estimation conversion.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "stride-length-calculator", "name": "Stride Length Calculator", "canonical_url": "https://boringtoolskit.com/stride-length-calculator/", "category": "Health", "description": "Stride length calculator: stride from height for walking or running.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "stripe-fee-calculator", "name": "Stripe Fee Calculator", "canonical_url": "https://boringtoolskit.com/stripe-fee-calculator/", "category": "Everyday Calculators", "description": "Calculate estimated Stripe fees, net proceeds, or the amount to charge for a target net. Starts with an editable 2.9% + $0.30 planning preset.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/paypal-fee-calculator/", "/shopify-profit-calculator/", "/sales-tax-vat-calculator/" ], "answer": "Calculate estimated Stripe fees, net proceeds, or the amount to charge for a target net. Starts with an editable 2.9% + $0.30 planning preset.", "formula": "Fee = amount × 2.9% + $0.30 (US standard online rate). Net = amount − fee. Rates vary by country, card type, and volume.", "example": "A $100 online payment: $100 × 2.9% + $0.30 = $3.20 in fees — net $96.80.", "assumptions": [ "The standard US online rate applies.", "No currency conversion or international card fees.", "The charge is a standard card payment." ], "sources": [ { "organization": "Wikipedia", "title": "Stripe, Inc.", "url": "https://en.wikipedia.org/wiki/Stripe,_Inc." }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How much does Stripe charge?", "2.9% + $0.30 per successful online charge in the US — $3.20 on a $100 payment." ], [ "How do I calculate the fee?", "Amount × 2.9% + $0.30." ], [ "Why is my rate different?", "International cards, currency conversion, and country-specific pricing change the rate." ], [ "Do refunds return the fee?", "Usually not — the processing fee is typically kept on refunded transactions." ], [ "How does Stripe compare to PayPal?", "Stripe is usually slightly cheaper (2.9% + $0.30 vs PayPal's 2.99% + $0.49 US) — compare at your ticket size." ], [ "Is there a monthly fee?", "No base monthly fee on the standard plan; paid features and volume pricing vary." ], [ "What counts as 'online'?", "Card-not-present charges — in-person terminal rates are lower (2.6% + $0.10)." ], [ "What is the Stripe fee?", "2.9% plus $0.30 per successful card charge in the US." ], [ "How much do I receive?", "Amount − fee: $100 − $3.20 = $96.80." ], [ "How do I net a target?", "Gross = (target + $0.30) ÷ 0.971 — the calculator does both directions." ] ] }, { "slug": "student-loan-payoff", "name": "Student Loan Payoff Calculator", "canonical_url": "https://boringtoolskit.com/student-loan-payoff/", "category": "Finance & Investing", "description": "Student loan payoff calculator: estimate your payoff months and see whether your monthly payment covers student loan interest.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/debt-payoff/", "/loan-comparison-calculator/", "/auto-loan-calculator/" ], "answer": "Student loan payoff calculator: estimate your payoff months and see whether your monthly payment covers student loan interest.", "formula": "Student loan payoff is simulated by applying a monthly payment to the balance and accruing interest at the monthly rate (annual rate ÷ 12). The calculator finds how many months (and total interest) it takes to clear the balance at that payment.", "example": "A $30,000 student loan at 5% with a $350 monthly payment pays off in about 107 months (roughly 9 years) and accrues roughly $7,200 in total interest.", "assumptions": [ "A fixed annual rate applied monthly (rate ÷ 12) on the outstanding balance.", "Payments are made on time and go to interest then principal.", "The estimate uses a simple monthly compounding model." ], "sources": [ { "organization": "Investopedia", "title": "Student Loan", "url": "https://www.investopedia.com/terms/s/student-loan.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How long does it take to pay off a student loan?", "It depends on your balance, rate, and payment. A higher payment finishes it faster. The calculator simulates this exactly for your numbers." ], [ "How do I reduce total interest?", "Pay more than the minimum each month, or make extra principal payments. Because interest accrues on the remaining balance, paying faster cuts the total." ], [ "Is it better to pay extra or invest?", "Generally, pay down high-interest debt first. If your student loan rate exceeds what you'd earn investing, paying it down is the smarter, guaranteed return." ], [ "What is the interest rate?", "The annual rate applied monthly. Federal student loans can have lower, fixed rates; private loans vary. If your rate is high, refinancing may help." ], [ "Does interest compound?", "Student loan interest is typically simple per-month on the outstanding balance (not compounding on unpaid interest), so paying on time keeps it from ballooning. Check your lender's policy." ], [ "Should I pay the minimum or more?", "If you want to minimize total interest, pay more than the minimum. Minimum payments can stretch the term and multiply the total interest." ], [ "What if I have multiple loans?", "Pay the highest-rate one first (avalanche) or the smallest first (snowball) — both work. The key is paying more than the minimum somewhere." ] ] }, { "slug": "study-time-calculator", "name": "Study Time Calculator", "canonical_url": "https://boringtoolskit.com/study-time-calculator/", "category": "School & Education", "description": "Study time calculator: hours per credit and per course versus the common 2-hours-per-credit rule.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "subnet-calculator", "name": "Subnet Calculator", "canonical_url": "https://boringtoolskit.com/subnet-calculator/", "category": "Text & Developer Tools", "description": "Calculate network address, broadcast, usable host range, subnet mask, and wildcard for any IPv4 address and CIDR prefix.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/hex-to-decimal/", "/unit-conv/", "/base64-tool/" ], "answer": "Calculate network address, broadcast, usable host range, subnet mask, and wildcard for any IPv4 address and CIDR prefix.", "formula": "From an IP and CIDR prefix (/n): network address = IP AND mask; broadcast = network OR (~mask); address count = 2^(32−n); usable hosts = count − 2. Example: 192.168.1.10/24 → network 192.168.1.0, broadcast 192.168.1.255, 254 usable hosts.", "example": "192.168.1.10/24: network 192.168.1.0, broadcast 192.168.1.255, 256 addresses, 254 usable hosts.", "assumptions": [ "IPv4 addressing and CIDR notation are used.", "Standard network/broadcast reservations apply.", "No VLSM or supernetting nuances are modeled." ], "sources": [ { "organization": "Wikipedia", "title": "Subnetwork", "url": "https://en.wikipedia.org/wiki/Subnetwork" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How does a subnet calculator work?", "It takes an IP and CIDR prefix, computes the network address (IP AND mask), broadcast (network OR ~mask), address count 2^(32−n), and usable hosts minus 2." ], [ "What is CIDR notation?", "The /n suffix stating how many bits are the network portion — /24 means 24 network bits and 8 host bits (256 addresses)." ], [ "How many usable hosts are in a /24?", "256 total minus 2 reserved (network + broadcast) = 254 usable hosts." ], [ "What are the network and broadcast addresses?", "The network is the first address (identifies the subnet); the broadcast is the last (sent to all hosts). Both are reserved." ], [ "What prefix should my home network use?", "Typically /24 (255.255.255.0) — 254 usable addresses, plenty for home use." ], [ "Is this for IPv6?", "No — the tool handles IPv4 CIDR. IPv6 uses similar concepts but different notation." ], [ "Why can't I use the first and last addresses?", "They're reserved by protocol for the network identifier and broadcast — assigning them to hosts breaks the subnet." ] ] }, { "slug": "subscription-churn-impact-calculator", "name": "Subscription Churn Impact Calculator", "canonical_url": "https://boringtoolskit.com/subscription-churn-impact-calculator/", "category": "Seller & Business", "description": "Model customer and recurring-revenue trajectory from constant churn, acquisition, ARPU, and horizon assumptions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/customer-lifetime-value-calculator/", "/cash-flow-runway-calculator/", "/break-even-units-calculator/" ], "answer": "Model customer and recurring-revenue trajectory from constant churn, acquisition, ARPU, and horizon assumptions.", "formula": "Monthly churn requires churn × customers new customers/month just to hold steady. The tool projects the customer base and revenue month by month given churn, new customers, and ARPU.", "example": "1,000 customers at 5% monthly churn need 50 new customers per month just to stay at 1,000 — anything less and the base shrinks.", "assumptions": [ "Churn, new customers, and ARPU are constant monthly rates.", "No seasonality or one-time events are modeled.", "Revenue is ARPU × customer count per month." ], "sources": [ { "organization": "Wikipedia", "title": "Churn rate", "url": "https://en.wikipedia.org/wiki/Churn_rate" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is churn?", "The rate at which customers cancel or stop paying — 5% monthly churn means losing 5% of customers each month." ], [ "How many new customers do I need to offset churn?", "Churn × customer count per month. 5% of 1,000 = 50 new customers monthly just to hold steady." ], [ "How fast does churn shrink the base?", "Exponentially: at 5% monthly churn, the base halves in about 14 months without new signups." ], [ "How do I reduce churn?", "Improve onboarding, deliver the core value faster, monitor usage drops, and reach out before cancellation." ], [ "What is ARPU?", "Average revenue per user — total subscription revenue divided by customer count. ARPU × customers = monthly revenue." ], [ "Why is retention cheaper than acquisition?", "Acquisition costs marketing and sales spend; retention costs product improvements and support — usually a fraction of the price." ], [ "What's a healthy churn rate?", "Under 2–3% monthly is strong for consumer subscriptions; B2B should be lower. It depends on your market." ], [ "What is churn rate?", "The percentage of subscribers who cancel in a period — usually monthly." ], [ "How does churn affect revenue?", "Each churned subscriber's revenue is lost forever; the impact compounds." ], [ "What is LTV and how does churn affect it?", "LTV = average revenue per user ÷ churn — lower churn means higher LTV." ], [ "What is a good churn rate?", "Under 5% monthly is healthy for most SaaS; under 2% is excellent." ] ] }, { "slug": "subscription-cost-calculator", "name": "Subscription Cost Calculator", "canonical_url": "https://boringtoolskit.com/subscription-cost-calculator/", "category": "Finance & Investing", "description": "Subscription cost calculator: the real annual cost of your recurring subscriptions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sugar-in-drinks-calculator", "name": "Sugar in Drinks Calculator", "canonical_url": "https://boringtoolskit.com/sugar-in-drinks-calculator/", "category": "Health", "description": "Sugar in drinks calculator: teaspoons and daily value from grams.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sump-pump-calculator", "name": "Sump Pump Calculator", "canonical_url": "https://boringtoolskit.com/sump-pump-calculator/", "category": "Construction & Measurement", "description": "Sump pump calculator: gallons per minute needed for a basement.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sun-moon-planner", "name": "Sun & Moon Planner", "canonical_url": "https://boringtoolskit.com/sun-moon-planner/", "category": "Everyday Calculators", "description": "Estimate sunrise, sunset, twilight, daylight, moon phase, moonrise, and moonset for a date and coordinates.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/us-weather-forecast/", "/world-clock/", "/printable-calendar/" ], "answer": "Estimate sunrise, sunset, twilight, daylight, moon phase, moonrise, and moonset for a date and coordinates.", "formula": "Shows the current moon phase and sun/moon timing data for planning: phase name, illumination, and relevant day/night timings.", "example": "A Full Moon phase is reported with its name and approximate illumination near 100%.", "assumptions": [ "The phase calculation uses standard lunar-cycle math.", "Location-specific rise/set times are approximate.", "The data is for planning, not navigation." ], "sources": [ { "organization": "Wikipedia", "title": "Lunar phase", "url": "https://en.wikipedia.org/wiki/Lunar_phase" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What moon phase is it right now?", "Open the planner — it shows the current phase and illumination." ], [ "How long is the lunar cycle?", "About 29.5 days from New Moon to the next New Moon." ], [ "What are the 8 phases?", "New, Waxing Crescent, First Quarter, Waxing Gibbous, Full, Waning Gibbous, Last Quarter, Waning Crescent." ], [ "Why does the Full Moon matter for stargazing?", "Full moonlight washes out faint stars — New Moon nights are best for deep-sky viewing." ], [ "Is this used for gardening?", "Some gardeners follow lunar planting calendars by phase — the planner shows where the cycle is." ], [ "How accurate is the phase?", "Approximate — exact times vary by location; the phase state is the reliable part." ], [ "Can I plan photography around it?", "Yes — moonlit landscape shots want the Full Moon; star trails want New." ], [ "What phase is the moon in now?", "The planner shows the current phase and approximate illumination." ], [ "When is best for stargazing?", "New Moon weeks — the darkest skies of the month." ], [ "Is the phase exact?", "The state is reliable; exact rise/set times vary by location." ] ] }, { "slug": "sunrise-sunset-calculator", "name": "Sunrise Sunset Calculator", "canonical_url": "https://boringtoolskit.com/sunrise-sunset-calculator/", "category": "Everyday Calculators", "description": "Sunrise sunset calculator: sunrise, sunset, and daylight hours for any city today plus the next week.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "sunscreen-spf-calculator", "name": "Sunscreen SPF Calculator", "canonical_url": "https://boringtoolskit.com/sunscreen-spf-calculator/", "category": "Health", "description": "Sunscreen SPF calculator: burn protection time and reapplication.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "surface-area-calculator", "name": "Surface Area Calculator", "canonical_url": "https://boringtoolskit.com/surface-area-calculator/", "category": "Everyday Calculators", "description": "Calculate the surface area of common 3D shapes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/volume-calculator/", "/circle-calculator/", "/square-footage-calculator/" ], "answer": "Calculate the surface area of common 3D shapes.", "formula": "Cube: 6a². Sphere: 4πr². Cylinder: 2πr² + 2πrh. Cone: πr² + πr√(r² + h²). The tool computes surface area from the shape's dimensions.", "example": "A cube with side 3 has surface area 6 × 9 = 54. A sphere with radius 2 has surface area 4π × 4 ≈ 50.27.", "assumptions": [ "The shape is a perfect geometric solid.", "All dimensions are in the same units.", "The shape is closed (all faces included)." ], "sources": [ { "organization": "Wikipedia", "title": "Surface area", "url": "https://en.wikipedia.org/wiki/Surface_area" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is surface area?", "The total area of a 3D object's outer surface — the sum of all its faces. A cube with side 3 has 6 faces of 9 = 54 sq units." ], [ "How do I find the surface area of a cube?", "6a² — six identical square faces. Side 3: 6 × 9 = 54." ], [ "How do I find the surface area of a sphere?", "4πr². Radius 2: 4π × 4 ≈ 50.27." ], [ "How do I find the surface area of a cylinder?", "2πr² + 2πrh — two circular ends plus the curved side. For an open cylinder, use just 2πrh." ], [ "What units should I use?", "Any, as long as they're consistent — the result is in square units (cm², m², ft², etc.)." ], [ "Why does surface area matter?", "It determines how much material covers an object: paint, insulation, plating, wrapping." ], [ "Can I combine shapes?", "Yes — decompose into simpler shapes, compute each, and add. Watch for shared faces you shouldn't double-count." ] ] }, { "slug": "swim-pace-calculator", "name": "Swim Pace Calculator", "canonical_url": "https://boringtoolskit.com/swim-pace-calculator/", "category": "Sports", "description": "Swim pace calculator: minutes per 100 meters from distance and time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "swimming-calories-calculator", "name": "Swimming Calories Calculator", "canonical_url": "https://boringtoolskit.com/swimming-calories-calculator/", "category": "Health", "description": "Swimming calories calculator: calories burned swimming by weight and time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "t-bill-yield-calculator", "name": "T-Bill Yield Calculator", "canonical_url": "https://boringtoolskit.com/t-bill-yield-calculator/", "category": "Finance & Investing", "description": "T-Bill yield calculator: discount yield from face value, price, and days to maturity.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "t-test-calculator", "name": "T Test Calculator", "canonical_url": "https://boringtoolskit.com/t-test-calculator/", "category": "Statistics", "description": "T test calculator: two-sample t statistic and significance.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "tank-volume-calculator", "name": "Tank Volume Calculator", "canonical_url": "https://boringtoolskit.com/tank-volume-calculator/", "category": "Construction & Measurement", "description": "Tank volume calculator: cylindrical tank capacity.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "tea-steep-calculator", "name": "Tea Steep Calculator", "canonical_url": "https://boringtoolskit.com/tea-steep-calculator/", "category": "Food & Cooking", "description": "Tea steep calculator: water temperature and time by tea type.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "telescope-magnification-calculator", "name": "Telescope Magnification Calculator", "canonical_url": "https://boringtoolskit.com/telescope-magnification-calculator/", "category": "Astronomy", "description": "Telescope magnification calculator: power from focal length and eyepiece.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "temperature-converter", "name": "Temperature Converter", "canonical_url": "https://boringtoolskit.com/temperature-converter/", "category": "Converters", "description": "Temperature converter: Celsius, Fahrenheit, and Kelvin.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "tempo-change-calculator", "name": "Tempo Change Calculator", "canonical_url": "https://boringtoolskit.com/tempo-change-calculator/", "category": "Music & Audio", "description": "Tempo change calculator: new BPM after shifting pitch by semitones.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "term-life-insurance-calculator", "name": "Term Life Insurance Calculator", "canonical_url": "https://boringtoolskit.com/term-life-insurance-calculator/", "category": "Finance & Investing", "description": "Term life insurance calculator: coverage need using the DIME method.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "text-case", "name": "Text Case Converter", "canonical_url": "https://boringtoolskit.com/text-case/", "category": "Converters", "description": "Change text case in one click — lower, upper, title, and sentence case. Free and private; nothing is uploaded. Paste and convert instantly.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/csv-to-json/", "/word-counter/", "/keyword-density-calculator/" ], "answer": "Change text case in one click — lower, upper, title, and sentence case. Free and private; nothing is uploaded. Paste and convert instantly.", "formula": "Transforms text casing: lower (all lowercase), upper (all uppercase), title (first letter of each word uppercase), and sentence (first letter after each sentence period uppercase).", "example": "'hello WORLD, welcome to btk' in title case → 'Hello World, Welcome To Btk'.", "assumptions": [ "The transformation rule is applied mechanically.", "Title case capitalizes every word's first letter.", "Sentence case uses period boundaries." ], "sources": [ { "organization": "Wikipedia", "title": "Letter case", "url": "https://en.wikipedia.org/wiki/Letter_case" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I change text case?", "Paste the text and click lower, upper, title, or sentence — the tool transforms it instantly in your browser." ], [ "What is title case?", "Capitalizing the first letter of each word: 'hello world' → 'Hello World'. Style guides vary on small words." ], [ "What is sentence case?", "Capitalizing only the first letter of each sentence: 'hello world. welcome' → 'Hello world. Welcome'." ], [ "Why are my proper nouns wrong?", "Mechanical conversion can't know 'iPhone' should stay capitalized. Touch up names and brands after converting." ], [ "Is my text uploaded?", "No — everything runs locally in your browser." ], [ "Which case should I use for headlines?", "Title case for most headlines; sentence case for modern, editorial-style headings." ], [ "Can I use it for code?", "For basic formatting yes, but programming conventions (camelCase, snake_case) need their own tools." ] ] }, { "slug": "thermal-equilibrium-calculator", "name": "Thermal Equilibrium Calculator", "canonical_url": "https://boringtoolskit.com/thermal-equilibrium-calculator/", "category": "Physics", "description": "Calculate the final temperature when two objects reach thermal equilibrium.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/calories-burned-calculator/", "/heat-index-calculator/", "/calorie-calc/" ], "answer": "Calculate the final temperature when two objects reach thermal equilibrium.", "formula": "Final temperature = (m₁·T₁ + m₂·T₂) ÷ (m₁ + m₂), assuming identical specific heat and no heat loss to the surroundings.", "example": "Mixing 2 kg of water at 80°C with 3 kg at 20°C: Tf = (2×80 + 3×20) ÷ 5 = (160 + 60) ÷ 5 = 44°C.", "assumptions": [ "Both substances have the same specific heat capacity.", "No heat is lost to the container or surroundings.", "Positive masses are required; temperatures may differ in sign." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "tiktok-money-calculator", "name": "TikTok Money Calculator", "canonical_url": "https://boringtoolskit.com/tiktok-money-calculator/", "category": "Social Media", "description": "Estimate TikTok earnings from views and creator fund rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/youtube-revenue-calculator/", "/social-media-earnings-calculator/", "/video-watch-time-calculator/" ], "answer": "Estimate TikTok earnings from views and creator fund rate.", "formula": "Estimated earnings = (views ÷ 1,000) × creator fund rate. The rate defaults to $0.03 per 1,000 when left blank.", "example": "1,000,000 views at $0.03 per 1,000: (1,000,000 ÷ 1,000) × 0.03 = $30.00.", "assumptions": [ "The creator fund rate is an estimate; payout varies by region, views, and program eligibility.", "Earnings are gross before any platform or tax deductions.", "The calculation only counts monetizable views. It does not include brand deals or live gifts." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "tile-calculator", "name": "Tile Calculator", "canonical_url": "https://boringtoolskit.com/tile-calculator/", "category": "Construction & Measurement", "description": "Estimate tiles and boxes required from surface and tile dimensions with waste.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/square-footage-calculator/", "/flooring-calculator/", "/paint-coverage-calculator/" ], "answer": "Estimate tiles and boxes required from surface and tile dimensions with waste.", "formula": "Surface area = area length × area width. Tile area = tile length × tile width ÷ 144 (sq ft). Tiles needed = ceil(surface area × (1 + waste%) ÷ tile area). Boxes = ceil(tiles needed ÷ tiles per box).", "example": "A 10 × 12 ft floor (120 sq ft) with 12×12 in tiles and 10% waste: needed = ceil(120 × 1.10 ÷ 1) = 132 tiles. At 10 tiles per box: ceil(132 ÷ 10) = 14 boxes.", "assumptions": [ "The surface is rectangular.", "Tiles are square or rectangular with dimensions entered in inches.", "Waste covers cuts, breakage, and future repairs." ], "sources": [ { "organization": "Bob Vila", "title": "How Much Tile Do I Need?", "url": "https://www.bobvila.com/articles/how-much-tile-do-i-need/" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate how many tiles I need?", "Divide the surface area (sq ft) by the area of one tile (sq ft), multiply by the waste factor, and round up. For 120 sq ft with 1 sq ft tiles, that's about 132 tiles with 10% waste." ], [ "How do I convert tile size to square feet?", "Multiply length × width in inches, then divide by 144. A 12×12 in tile = 1 sq ft; a 6×24 in tile = 1 sq ft too." ], [ "How much extra tile should I buy?", "10–15% is standard for straight layouts. Diagonal patterns and rooms with many cuts can need 20% or more. Extra tile is also insurance for future repairs." ], [ "Do grout lines affect the count?", "Negligibly — grout lines are small fractions of an inch and don't change whole-tile counts materially." ], [ "Why round up to whole boxes?", "Tile is sold by the box. Buying whole boxes ensures you have matching dye lots for the whole job." ], [ "What about wall vs floor tile?", "The math is the same. Just measure the wall surface (width × height, minus openings) the same way." ], [ "What if my room isn't rectangular?", "Split it into rectangles, calculate each, and add them. The tool assumes one rectangle per calculation." ] ] }, { "slug": "tile-count-calculator", "name": "Tile Count Calculator", "canonical_url": "https://boringtoolskit.com/tile-count-calculator/", "category": "Construction & Measurement", "description": "Tile count calculator: tiles needed for a floor or wall.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "time-card-calculator", "name": "Time Card Calculator", "canonical_url": "https://boringtoolskit.com/time-card-calculator/", "category": "Time & Work", "description": "Calculate work hours, lunch deductions, overtime, and estimated gross pay.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/paycheck-calc/", "/overtime-calculator/", "/salary-hourly-converter/" ], "answer": "Calculate work hours, lunch deductions, overtime, and estimated gross pay.", "formula": "Daily hours = (end time − start time − lunch) in hours. Total = daily hours × days worked. Overtime: hours above the daily/weekly threshold paid at the overtime rate.", "example": "Working 9:00–17:30 with a 30-minute lunch = 8.0 hours per day.", "assumptions": [ "The schedule is the same each day.", "One unpaid lunch break per day.", "Overtime threshold is the entered value." ], "sources": [ { "organization": "Wikipedia", "title": "Timesheet", "url": "https://en.wikipedia.org/wiki/Timesheet" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate hours worked?", "End time minus start time minus lunch: 9:00–17:30 with 30 min lunch = 8.0 hours." ], [ "How do I handle different schedules?", "Calculate each day separately or enter the average — the tool assumes a consistent daily schedule." ], [ "What counts as overtime?", "It depends on your jurisdiction — often hours over 40/week or 8/day. The tool flags hours above your entered threshold." ], [ "Is lunch paid or unpaid?", "The tool subtracts it as unpaid — which is standard for hourly workers in most places." ], [ "How do I convert minutes to decimals?", "Divide by 60: 30 min = 0.5 hours. The tool handles the conversion." ], [ "How do I verify my paystub?", "Total your hours with the tool and multiply by your rate — then compare to the gross on your stub." ], [ "What about overtime pay?", "Enter the overtime hours at 1.5× your rate (or your company's policy) separately." ], [ "How do I calculate hours on a time card?", "Sum clock-out minus clock-in per day, minus unpaid breaks." ], [ "How are breaks handled?", "Unpaid breaks subtract; paid breaks don't — the calculator follows your rule." ], [ "What is overtime?", "Hours over 40 weekly (or daily in some states) at time and a half." ], [ "Should I track my own time?", "Yes — comparing your total to the stub catches rounding and policy errors." ] ] }, { "slug": "time-to-decimal-calculator", "name": "Time to Decimal Calculator", "canonical_url": "https://boringtoolskit.com/time-to-decimal-calculator/", "category": "Time & Work", "description": "Convert hours and minutes to decimal hours for payroll and timesheets , and decimal hours back to hours and minutes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/time-card-calculator/", "/hours-minutes-calculator/", "/overtime-calculator/" ], "answer": "Convert hours and minutes to decimal hours for payroll and timesheets , and decimal hours back to hours and minutes.", "formula": "Decimal hours = hours + minutes ÷ 60. Decimal minutes = total minutes. The tool converts both directions: time ↔ decimal.", "example": "8 hours 30 minutes = 8.5 decimal hours (or 510 decimal minutes).", "assumptions": [ "Standard 60-minute hour conversion.", "No payroll rounding is applied.", "The user converts in either direction." ], "sources": [ { "organization": "Wikipedia", "title": "Decimal time", "url": "https://en.wikipedia.org/wiki/Decimal_time" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I convert time to decimal?", "Hours + minutes ÷ 60: 8h 30m = 8.5 hours." ], [ "Why is 90 minutes 1.5 hours?", "Time is base-60 — 90 ÷ 60 = 1.5, not 1.90." ], [ "What is decimal time used for?", "Payroll, billing, and spreadsheets, which calculate in decimal hours." ], [ "How do I convert decimal back to time?", "Separate the fraction: 8.5 hours = 8 hours + 0.5 × 60 = 8:30." ], [ "Does payroll round?", "Many systems round to 6- or 15-minute increments — check your employer's rule." ], [ "What are decimal minutes?", "Total minutes: 8.5 hours = 510 minutes." ], [ "Is this the same as the time card calculator?", "The time card totals work hours; this converts between time and decimal formats." ] ] }, { "slug": "time-zone-meeting-planner", "name": "Time Zone Meeting Planner", "canonical_url": "https://boringtoolskit.com/time-zone-meeting-planner/", "category": "Time & Work", "description": "Compare a meeting time across common world time zones using browser time-zone data.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/timezone-converter/", "/world-clock/", "/business-days-calculator/" ], "answer": "Compare a meeting time across common world time zones using browser time-zone data.", "formula": "Converts a meeting time in the organizer's zone to each participant's local time using IANA zone offsets, handling daylight saving automatically.", "example": "A 3:00 PM New York meeting shows as 12:00 PM in Los Angeles and 8:00 PM in London (summer).", "assumptions": [ "IANA zone names are used.", "DST rules apply for the meeting date.", "The chosen time is the organizer's local time." ], "sources": [ { "organization": "Wikipedia", "title": "Time zone", "url": "https://en.wikipedia.org/wiki/Time_zone" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I plan a meeting across time zones?", "Enter each participant's zone and the proposed time — the planner shows everyone's local time." ], [ "Does it handle daylight saving?", "Yes — it applies each zone's DST rules for the specific date." ], [ "What's the best time for a global team?", "Convert everyone's working hours to UTC and find the overlap — typically mornings in the Americas or afternoons in Europe." ], [ "Why do some zones not change for DST?", "Arizona (most of it), Hawaii, and many countries don't observe DST — the planner knows." ], [ "What happens during spring-forward?", "A nonexistent local time (2:00–3:00 AM) resolves to the nearest valid offset." ], [ "How is this different from the timezone converter?", "The planner handles many zones at once — the converter does one pair." ], [ "Does it send invites?", "No — it computes the times; you create the invite with the results." ], [ "What is the best time for a global call?", "The overlap of working hours — often early morning Pacific / late afternoon Europe." ], [ "Is it the same as a world clock?", "The world clock shows now; the planner schedules a specific time." ] ] }, { "slug": "timelapse-calculator", "name": "Timelapse Calculator", "canonical_url": "https://boringtoolskit.com/timelapse-calculator/", "category": "Photo & Video", "description": "Timelapse calculator: frames and finished clip length from capture interval and duration.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "timezone-converter", "name": "Timezone Converter", "canonical_url": "https://boringtoolskit.com/timezone-converter/", "category": "Everyday Calculators", "description": "Convert a time between cities and time zones worldwide with automatic daylight saving adjustment. Compare multiple zones at once, privately, no account.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/date-difference-calculator/", "/business-days-calculator/", "/age-calculator/" ], "answer": "Convert a time between cities and time zones worldwide with automatic daylight saving adjustment. Compare multiple zones at once, privately, no account.", "formula": "Converts a wall time in one IANA time zone to another by resolving the instant (UTC) via each zone's offset, including daylight saving adjustments.", "example": "3:00 PM EDT in New York is 7:00 PM UTC and 8:00 PM BST in London during summer.", "assumptions": [ "IANA zone names are used.", "The entered time is local wall time in the source zone.", "DST rules are applied for the date in question." ], "sources": [ { "organization": "Wikipedia", "title": "Time zone", "url": "https://en.wikipedia.org/wiki/Time_zone" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I convert between time zones?", "Pick the source and target zones, enter the local time, and the converter shows the same instant in both." ], [ "Does it handle daylight saving?", "Yes — it applies each zone's DST rules for the specific date." ], [ "What is UTC?", "Coordinated Universal Time — the reference all zones offset from. NY is UTC−4 in summer, UTC−5 in winter." ], [ "Why are some zones half-hour offsets?", "Historical and political choices — India (UTC+5:30), Nepal (UTC+5:45), and others." ], [ "What happens around DST changes?", "Spring forward skips an hour; fall back repeats one. Times inside those transitions resolve to the nearest valid offset." ], [ "What's the best time for a meeting across zones?", "Convert everyone's 9–5 range to UTC and find the overlap — the converter does the individual legs." ], [ "Is this the same as the world clock?", "Similar — the converter handles any pair of zones at a chosen time; the world clock shows current times everywhere." ] ] }, { "slug": "tip-bill-split-calculator", "name": "Tip & Bill Split Calculator", "canonical_url": "https://boringtoolskit.com/tip-bill-split-calculator/", "category": "Everyday Calculators", "description": "Calculate a tip, split a bill evenly, and make rounding choices explicit.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/sales-tax-vat-calculator/", "/percentage-calc/", "/discount-percent-off-calculator/" ], "answer": "Calculate a tip, split a bill evenly, and make rounding choices explicit.", "formula": "Per person = (subtotal + tax) × (1 + tip %) ÷ people, optionally rounding each share. The tool supports tipping on subtotal or on subtotal + tax.", "example": "$100 subtotal, 8% tax, 20% tip, split 4 ways: ($108 × 1.20) ÷ 4 = $32.40 each.", "assumptions": [ "The bill is split equally.", "Tip and tax are entered as percentages.", "The US tipping norm applies unless stated." ], "sources": [ { "organization": "Wikipedia", "title": "Gratuity", "url": "https://en.wikipedia.org/wiki/Gratuity" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I split a bill with tip?", "(Subtotal + tax) × (1 + tip%) ÷ people: $108 × 1.2 ÷ 4 = $32.40 each." ], [ "Should I tip on pre-tax or post-tax?", "US convention is pre-tax; tipping on the taxed total is more generous. The tool shows both." ], [ "What tip percentage is standard?", "15–20% in the US; many countries include service in the bill." ], [ "How do I handle uneven splits?", "This tool splits equally — total each person's items separately for uneven shares." ], [ "How do I round shares?", "Round each share to the nearest dollar or quarter — the tool offers rounding modes." ], [ "Who pays the tax?", "Everyone equally in an equal split — the calculator includes it." ], [ "Is 20% tip on tax double-dipping?", "Arguably — that's why the tool lets you tip on the pre-tax subtotal." ], [ "Should I tip on the pre-tax amount?", "Convention varies; tipping on the subtotal is common and fair." ], [ "How do I handle rounding?", "Agree up front — rounding each share up covers the difference." ] ] }, { "slug": "tire-pressure-calculator", "name": "Tire Pressure Calculator", "canonical_url": "https://boringtoolskit.com/tire-pressure-calculator/", "category": "Vehicles", "description": "Tire pressure calculator: psi change with temperature.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "tire-size-comparison-calculator", "name": "Tire Size Comparison Calculator", "canonical_url": "https://boringtoolskit.com/tire-size-comparison-calculator/", "category": "Vehicles", "description": "Tire size comparison calculator: diameter difference and speedometer error between two tire sizes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "tire-tread-depth-calculator", "name": "Tire Tread Depth Calculator", "canonical_url": "https://boringtoolskit.com/tire-tread-depth-calculator/", "category": "Vehicles", "description": "Tire tread depth calculator: remaining life from tread depth.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "title-case-converter", "name": "Title Case Converter", "canonical_url": "https://boringtoolskit.com/title-case-converter/", "category": "Converters", "description": "Title case converter: convert any text to title case with proper small-word handling.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "titration-calculator", "name": "Titration Calculator", "canonical_url": "https://boringtoolskit.com/titration-calculator/", "category": "Chemistry", "description": "Calculate solution concentrations and equivalence points in titration.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/ph-calculator/", "/molarity-calculator/", "/buffer-solution-calculator/" ], "answer": "Calculate solution concentrations and equivalence points in titration.", "formula": "Acid-base titration uses MₐVₐ × H⁺ = M_bV_b × OH⁻ at the equivalence point (moles of H⁺ = moles of OH⁻).", "example": "For 25 mL of 0.1 M HCl (1 H⁺) titrated with 0.2 M NaOH (1 OH⁻): V_b = (0.1 × 25 × 1) ÷ (0.2 × 1) = 12.5 mL.", "assumptions": [ "Molarity, volume, and the H⁺/OH⁻ per molecule are entered for the known side.", "The calculation applies to the equivalence point of a complete neutralization.", "The H⁺ per acid and OH⁻ per base values must be positive (e.g. 1 for HCl, 2 for H₂SO₄)." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "toilet-water-calculator", "name": "Toilet Water Calculator", "canonical_url": "https://boringtoolskit.com/toilet-water-calculator/", "category": "Construction & Measurement", "description": "Toilet water calculator: gallons used per year.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "toll-cost-calculator", "name": "Toll Cost Calculator", "canonical_url": "https://boringtoolskit.com/toll-cost-calculator/", "category": "Travel", "description": "Toll cost calculator: weekly and yearly toll spend from per-trip cost.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "torque-converter", "name": "Torque Converter", "canonical_url": "https://boringtoolskit.com/torque-converter/", "category": "Converters", "description": "Torque converter: newton-meters, foot-pounds, inch-pounds.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "towing-capacity-calculator", "name": "Towing Capacity Calculator", "canonical_url": "https://boringtoolskit.com/towing-capacity-calculator/", "category": "Vehicles", "description": "Towing capacity calculator: safe trailer weight from rated capacity minus payload and driver.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "transformer-calculator", "name": "Transformer Calculator", "canonical_url": "https://boringtoolskit.com/transformer-calculator/", "category": "Energy & Electrical", "description": "Transformer calculator: output voltage or turns ratio for an ideal transformer.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "trapezoid-area-calculator", "name": "Trapezoid Area Calculator", "canonical_url": "https://boringtoolskit.com/trapezoid-area-calculator/", "category": "Everyday Calculators", "description": "Trapezoid area calculator: area from bases and height.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-27", "related_urls": [], "answer": "Trapezoid area calculator: area from bases and height.", "formula": "Area = (a + b)/2 × h, where a and b are the parallel bases and h is the perpendicular height.", "example": "Bases 6 m and 10 m, height 4 m → area = 8 × 4 = 32 m².", "assumptions": [ "Standard geometric or arithmetic definitions apply.", "Inputs use the units you choose.", "Results are estimates, not professional advice." ], "sources": [ { "organization": "Standard mathematics definitions", "title": "Arithmetic and geometry formulas", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "travel-budget-calculator", "name": "Travel Budget Calculator", "canonical_url": "https://boringtoolskit.com/travel-budget-calculator/", "category": "Travel", "description": "Travel budget calculator: daily spending plus flights, hotels, and extras.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "travel-reimbursement-calculator", "name": "Travel Reimbursement Calculator", "canonical_url": "https://boringtoolskit.com/travel-reimbursement-calculator/", "category": "Time & Work", "description": "Travel reimbursement calculator: mileage, meals and lodging claim.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "triangle-area-calculator", "name": "Triangle Area Calculator", "canonical_url": "https://boringtoolskit.com/triangle-area-calculator/", "category": "School & Education", "description": "Triangle area calculator: area from base and height.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "triangle-calculator", "name": "Triangle Calculator", "canonical_url": "https://boringtoolskit.com/triangle-calculator/", "category": "Everyday Calculators", "description": "Solve any triangle from its three sides: area, angles, height, inradius, circumradius, and perimeter.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/pythagorean-theorem-calculator/", "/circle-calculator/", "/surface-area-calculator/" ], "answer": "Solve any triangle from its three sides: area, angles, height, inradius, circumradius, and perimeter.", "formula": "Solves triangles from given sides/angles: area = ½ × base × height, and via Heron's formula from three sides. Angles sum to 180°.", "example": "A triangle with base 10 and height 5: area = ½ × 10 × 5 = 25 square units.", "assumptions": [ "Angles are in degrees.", "Inputs satisfy the triangle inequality.", "Standard Euclidean geometry applies." ], "sources": [ { "organization": "Wikipedia", "title": "Triangle", "url": "https://en.wikipedia.org/wiki/Triangle" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I find the area of a triangle?", "½ × base × height: ½ × 10 × 5 = 25 square units." ], [ "What if I only know the three sides?", "Use Heron's formula — the tool handles it." ], [ "Do all triangles have 180°?", "Yes — in Euclidean geometry, the three angles always sum to 180°." ], [ "What is the triangle inequality?", "Each side must be shorter than the sum of the other two, or the triangle can't exist." ], [ "Can it solve right triangles?", "Yes — it covers them; the Pythagorean calculator is the faster special case." ], [ "What units does it use?", "Any consistent unit — the area comes out in the same unit squared." ], [ "What is an ambiguous case?", "Side-side-angle data can produce two valid triangles — a known trap in trigonometry." ] ] }, { "slug": "trig-calculator", "name": "Trig Calculator", "canonical_url": "https://boringtoolskit.com/trig-calculator/", "category": "Everyday Calculators", "description": "Trig calculator: sine, cosine, tangent of an angle.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "true-shooting-percentage-calculator", "name": "True Shooting Percentage Calculator", "canonical_url": "https://boringtoolskit.com/true-shooting-percentage-calculator/", "category": "Sports", "description": "True shooting percentage calculator: TS% accounting for free throws.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "tsp-tablespoon-converter", "name": "Tsp to Tbsp Converter", "canonical_url": "https://boringtoolskit.com/tsp-tablespoon-converter/", "category": "Food & Cooking", "description": "Tsp to tbsp converter: teaspoons, tablespoons, cups, ml.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "typing-test", "name": "Typing Test", "canonical_url": "https://boringtoolskit.com/typing-test/", "category": "Text & Developer Tools", "description": "Measure words per minute, accuracy, errors, and progress with a local timed typing test.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/stopwatch/", "/word-counter/", "/readability/" ], "answer": "Measure words per minute, accuracy, errors, and progress with a local timed typing test.", "formula": "Words per minute = (words typed ÷ minutes elapsed). Accuracy = (correct characters ÷ total characters) × 100. The test times a practice passage and reports both.", "example": "Typing a 40-word passage in 60 seconds = 40 WPM; 95% accuracy means 95 of every 100 characters were correct.", "assumptions": [ "The user types the passage in order.", "WPM is calculated from the completed passage.", "Accuracy counts character-level correctness." ], "sources": [ { "organization": "Wikipedia", "title": "Words per minute", "url": "https://en.wikipedia.org/wiki/Words_per_minute" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How is typing speed measured?", "Words per minute: words typed divided by time. Typing a 40-word passage in 60 seconds = 40 WPM." ], [ "What is a good typing speed?", "Average is about 40 WPM; 60+ is above average, 80+ is fast, and professional typists often exceed 100 WPM." ], [ "What is accuracy in typing?", "The percentage of characters typed correctly. 95% accuracy with decent speed beats 100% speed with constant errors." ], [ "How do I improve my WPM?", "Practice daily with correct form: home row position, touch typing, and accuracy first. Speed follows accuracy." ], [ "Does the test count errors?", "It reports accuracy — the share of correct characters. Practice aiming for 95%+ accuracy." ], [ "How long should I practice?", "10–20 minutes of focused daily practice improves speed measurably over weeks." ], [ "Why is my WPM different in real work?", "Real typing includes code, symbols, and unfamiliar words — set passages are easier than mixed real content." ] ] }, { "slug": "unit-conv", "name": "Unit Converter", "canonical_url": "https://boringtoolskit.com/unit-conv/", "category": "Converters", "description": "Convert common units instantly across length, area, weight, temperature, volume, speed, and pressure.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/liters-to-ounces/", "/baking-conversions/", "/scientific-notation-converter/" ], "answer": "Convert common units instantly across length, area, weight, temperature, volume, speed, and pressure.", "formula": "Converts between units by scaling to a base unit and then to the target (e.g., inches → meters → kilometers). Supported families: length, area, weight, temperature, volume, speed, pressure.", "example": "1 mile converts to 1.609 km. 1 inch converts to 2.54 cm. 100°F converts to 37.8°C.", "assumptions": [ "Standard SI-derived conversion factors are used.", "Temperature uses the standard formulas.", "Area-length conversions assume a constant width." ], "sources": [ { "organization": "Wikipedia", "title": "International System of Units", "url": "https://en.wikipedia.org/wiki/International_System_of_Units" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I convert units?", "Choose the family (length, weight, etc.), enter the value, pick the from/to units, and read the result." ], [ "Which units are supported?", "Length, area, weight, temperature, volume, speed, and pressure — metric and imperial." ], [ "How do I convert temperature?", "Use the temperature family — it applies the correct offset formulas (°C = (°F − 32) × 5/9), not simple scaling." ], [ "Why isn't 1 m² = 3.28 ft²?", "Area factors square the linear factor: 1 m² = 10.764 ft². The converter handles this correctly." ], [ "What is the area-length mode?", "It converts between square area and linear length when you know the material width — e.g., square feet of flooring to linear feet of a roll." ], [ "Is it accurate?", "Yes — conversions go through standard base units (meters, kilograms, seconds) with precise factors." ], [ "Can I convert speed and pressure?", "Yes — km/h to mph, kPa to psi, and more are included in their families." ] ] }, { "slug": "unit-price-calculator", "name": "Unit Price Calculator", "canonical_url": "https://boringtoolskit.com/unit-price-calculator/", "category": "Finance & Investing", "description": "Unit price calculator: price per unit to compare package sizes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "us-eu-size-converter", "name": "US to EU Size Converter", "canonical_url": "https://boringtoolskit.com/us-eu-size-converter/", "category": "Converters", "description": "US to EU size converter: general clothing conversion.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "us-weather-forecast", "name": "US Weather Forecast", "canonical_url": "https://boringtoolskit.com/us-weather-forecast/", "category": "Everyday Calculators", "description": "Official National Weather Service forecast for US latitude and longitude coordinates. Enter exact coords for the authoritative federal NWS forecast, hourly a.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/weather-lookup/", "/timezone-converter/", "/sun-moon-planner/" ], "answer": "Official National Weather Service forecast for US latitude and longitude coordinates. Enter exact coords for the authoritative federal NWS forecast, hourly a.", "formula": "Pulls official National Weather Service forecasts: geocodes the location, then fetches current conditions and the multi-day forecast from NWS API endpoints.", "example": "Entering a ZIP or city shows the current conditions and the NWS forecast for the coming days.", "assumptions": [ "The location is in the US.", "The NWS API is reachable.", "The forecast is used for planning, not safety-critical decisions." ], "sources": [ { "organization": "Wikipedia", "title": "National Weather Service", "url": "https://en.wikipedia.org/wiki/National_Weather_Service" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I get the US forecast?", "Enter a ZIP code or city — the tool pulls the official NWS forecast." ], [ "Is this data reliable?", "It's the National Weather Service — the official US source used by most apps." ], [ "Does it cover international locations?", "No — the NWS covers the US. Use the weather lookup for global cities." ], [ "How far ahead does it forecast?", "Several days — check the tool for the current horizon." ], [ "Where are severe weather warnings?", "On weather.gov — the official alert channel. This tool shows conditions, not warnings." ], [ "Why is the forecast different from my app?", "Different models and update times — small differences are normal." ], [ "Is my search private?", "Yes — the request goes directly to the geocoding and NWS APIs without an account." ] ] }, { "slug": "username-scrambler", "name": "Username Scrambler", "canonical_url": "https://boringtoolskit.com/username-scrambler/", "category": "Everyday Calculators", "description": "Generate randomized but memorable username ideas from your real name or email prefix, entirely in your browser.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/random-name-picker/", "/random-number-generator/", "/text-case/" ], "answer": "Generate randomized but memorable username ideas from your real name or email prefix, entirely in your browser.", "formula": "Generates username variants from a base name using suffixes, numbers, separators, and random elements.", "example": "From 'alex', the tool generates options like alex_2026, alex.rider, alex_x7, and similar available-feeling handles.", "assumptions": [ "The base name is the user's starting point.", "Variants are ideas, not availability checks.", "Consistency across platforms is desirable." ], "sources": [ { "organization": "Wikipedia", "title": "Username", "url": "https://en.wikipedia.org/wiki/Username" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What does a username scrambler do?", "Generates username variants from your base name — with numbers, separators, and suffixes." ], [ "Does it check availability?", "No — it creates ideas. Check each candidate on the platform." ], [ "How do I make a good username?", "Short, memorable, consistent across platforms, and easy to spell." ], [ "Why do I need variants?", "Your first-choice handle is often taken — variants give you options to test." ], [ "Can I use numbers and symbols?", "The tool generates them; platform rules vary on which characters are allowed." ], [ "Should my handles match everywhere?", "Yes — consistency makes you findable and harder to impersonate." ], [ "Is this good for brand names?", "Similar logic — test the base name across platforms before committing." ], [ "What makes a good username?", "Short, memorable, consistent across platforms, and easy to spell." ] ] }, { "slug": "uuid-generator", "name": "UUID Generator", "canonical_url": "https://boringtoolskit.com/uuid-generator/", "category": "Text & Developer Tools", "description": "UUID generator: version 4 UUIDs for developers.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "uv-exposure-calculator", "name": "UV Exposure Calculator", "canonical_url": "https://boringtoolskit.com/uv-exposure-calculator/", "category": "Health", "description": "UV exposure calculator: minutes until sunburn by UV index and Fitzpatrick skin type.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "va-mortgage-calculator", "name": "VA Mortgage Calculator", "canonical_url": "https://boringtoolskit.com/va-mortgage-calculator/", "category": "Finance & Investing", "description": "VA mortgage calculator: VA loan with funding fee, no PMI.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "vacancy-rate-calculator", "name": "Vacancy Rate Calculator", "canonical_url": "https://boringtoolskit.com/vacancy-rate-calculator/", "category": "Real Estate", "description": "Vacancy rate calculator: percentage of time a rental sits empty across a year.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "vacancy-rate-impact-calculator", "name": "Vacancy Rate Impact Calculator", "canonical_url": "https://boringtoolskit.com/vacancy-rate-impact-calculator/", "category": "Finance & Investing", "description": "Stress-test rental cash flow against vacancy. Enter normal cash flow and vacancy rate to see how lost rent eats your return.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/rental-yield-calculator/", "/cash-flow-calculator/", "/net-operating-income-calculator/" ], "answer": "Stress-test rental cash flow against vacancy. Enter normal cash flow and vacancy rate to see how lost rent eats your return.", "formula": "Net occupied income = monthly rent × (1 − vacancy rate) − operating costs − fees. Vacancy reduces the rental income the property actually collects, so the metric shows the effective income after vacancy and costs.", "example": "With $2,000 monthly rent, a 5% vacancy rate ($1,900 effective rent), $350 costs, and $100 fees, net occupied income = $1,900 − $350 − $100 = $1,450/month.", "assumptions": [ "Vacancy rate is the proportion of rent not collected, entered as a percentage.", "Operating costs and fees are monthly figures.", "The result is the effective monthly income after vacancy and direct costs." ], "sources": [ { "organization": "Investopedia", "title": "Vacancy Rate", "url": "https://www.investopedia.com/terms/v/vacancy-rate.asp" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a normal vacancy rate?", "It varies by market. A common default is 5–8%. Strong markets run lower; weaker ones can be 10%+." ], [ "How does vacancy affect income?", "Vacancy reduces the rent you actually collect. A 5% vacancy on $2,000 rent means $100/month lost — or $1,200/year." ], [ "How do I calculate net occupied income?", "Net = (monthly rent × (1 − vacancy rate)) − operating costs − fees." ], [ "Should I use my market's actual vacancy rate?", "Yes — the real local vacancy rate matters more than a generic number. Use a rate that reflects where the property is." ], [ "What else does vacancy cost?", "Beyond lost rent, turnover costs: advertising, screening, cleaning, and lost days between tenants. Those are separate from the vacancy %." ], [ "Is a single vacant month a big deal?", "Yes. One empty month is effectively an 8%+ vacancy for the year, which can wipe out a modest annual cash flow." ], [ "Why budget for vacancy?", "Cash-flow projections that ignore vacancy overstate income. Budgeting a vacancy allowance makes your estimate survive reality." ] ] }, { "slug": "vacation-accrual-calculator", "name": "Vacation Accrual Calculator", "canonical_url": "https://boringtoolskit.com/vacation-accrual-calculator/", "category": "Time & Work", "description": "Vacation accrual calculator: PTO hours per pay period and per year.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "variance-calculator", "name": "Variance Calculator", "canonical_url": "https://boringtoolskit.com/variance-calculator/", "category": "Everyday Calculators", "description": "Calculate sample or population variance from a data set. Enter values to see variance, standard deviation, and the sum of squared deviations.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/statistics-calculator/", "/standard-error-calculator/", "/coefficient-of-variation-calculator/" ], "answer": "Calculate sample or population variance from a data set. Enter values to see variance, standard deviation, and the sum of squared deviations.", "formula": "Variance σ² (population) = Σ(x − mean)² ÷ n. Sample variance s² = Σ(x − mean)² ÷ (n − 1).", "example": "For 2, 4, 6, 8: mean = 5. Population variance = (9 + 1 + 1 + 9) ÷ 4 = 5.0, so population σ ≈ 2.24. Sample variance = 20 ÷ 3 = 6.67, so sample s ≈ 2.58.", "assumptions": [ "Variance needs at least two numbers.", "The sample formula (÷ n−1) better estimates a larger population from a smaller sample.", "The population formula (÷ n) applies when the data is the complete set." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "NIST/SEMATECH e-Handbook of Statistical Methods", "url": "https://www.itl.nist.gov/div898/handbook/" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "vehicle-depreciation-calculator", "name": "Vehicle Depreciation Calculator", "canonical_url": "https://boringtoolskit.com/vehicle-depreciation-calculator/", "category": "Vehicles", "description": "Vehicle depreciation calculator: projected value after years of ownership at a depreciation rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "velocity-calculator", "name": "Velocity Calculator", "canonical_url": "https://boringtoolskit.com/velocity-calculator/", "category": "Physics", "description": "Calculate velocity from distance and time, with km/h and mph conversions.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/acceleration-calculator/", "/momentum-calculator/", "/kinetic-energy-calculator/" ], "answer": "Calculate velocity from distance and time, with km/h and mph conversions.", "formula": "Velocity (v) = distance ÷ time. Conversions: km/h = v × 3.6; mph = v × 2.236936.", "example": "A car travels 300 m in 20 s: v = 300 ÷ 20 = 15 m/s = 54 km/h = 33.6 mph.", "assumptions": [ "Distance is in meters and time in seconds.", "Velocity assumes constant motion over the interval.", "Positive values are required." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "vertical-jump-calculator", "name": "Vertical Jump Calculator", "canonical_url": "https://boringtoolskit.com/vertical-jump-calculator/", "category": "Sports", "description": "Vertical jump calculator: jump height from hang time (free-flight physics).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "video-file-size-calculator", "name": "Video File Size Calculator", "canonical_url": "https://boringtoolskit.com/video-file-size-calculator/", "category": "Photo & Video", "description": "Video file size calculator: estimate file size from bitrate, resolution, frame rate, and duration.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "video-watch-time-calculator", "name": "Video Watch Time Calculator", "canonical_url": "https://boringtoolskit.com/video-watch-time-calculator/", "category": "Social Media", "description": "Calculate total video watch hours from views and average duration.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/youtube-revenue-calculator/", "/tiktok-money-calculator/", "/post-frequency-calculator/" ], "answer": "Calculate total video watch hours from views and average duration.", "formula": "Total watch time in seconds = views × average view duration. Hours = seconds ÷ 3,600. Days = hours ÷ 24.", "example": "50,000 views at 45 seconds average view: total = 2,250,000 sec = 625 hours ≈ 26.0 days.", "assumptions": [ "Average view duration is the user's estimate from analytics.", "Watch time is summed across all views.", "Retention is assumed constant; real watch time varies by video length and audience." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "vinyl-rpm-calculator", "name": "Vinyl RPM Calculator", "canonical_url": "https://boringtoolskit.com/vinyl-rpm-calculator/", "category": "Music & Audio", "description": "Calculate pitch change when a record plays at the wrong turntable speed.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/audio-time-stretch-calculator/", "/bpm-to-ms-calculator/", "/frequency-to-note-calculator/" ], "answer": "Calculate pitch change when a record plays at the wrong turntable speed.", "formula": "Pitch change % = (actual speed ÷ standard RPM − 1) × 100. Speed ratio = actual ÷ standard.", "example": "A 45 RPM record played at 33.33 RPM: ratio = 33.33 ÷ 45 = 0.74, pitch change ≈ −25.9%, so it plays slower and lower.", "assumptions": [ "The standard speed is 33, 45, or 78 RPM (entered).", "Pitch and duration change proportionally with speed.", "The actual turntable speed is the user's input." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "vitamin-d-calculator", "name": "Vitamin D Calculator", "canonical_url": "https://boringtoolskit.com/vitamin-d-calculator/", "category": "Health", "description": "Vitamin D calculator: IU to mcg conversion with daily reference.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "vo2-max-calculator", "name": "VO2 Max Calculator", "canonical_url": "https://boringtoolskit.com/vo2-max-calculator/", "category": "Health", "description": "VO2 max calculator: estimate aerobic fitness from a 12-minute run or resting heart rate.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "vo2max-calculator", "name": "VO2 Max Calculator", "canonical_url": "https://boringtoolskit.com/vo2max-calculator/", "category": "Health", "description": "VO2 max calculator: estimate from a 12-minute Cooper test.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "voltage-drop-calculator", "name": "Voltage Drop Calculator", "canonical_url": "https://boringtoolskit.com/voltage-drop-calculator/", "category": "Everyday Calculators", "description": "Estimate voltage drop in a wire run based on length, current, and wire gauge.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/watts-to-amps-calculator/", "/electricity-cost-calculator/", "/battery-runtime-calculator/" ], "answer": "Estimate voltage drop in a wire run based on length, current, and wire gauge.", "formula": "Voltage drop = 2 × one-way length × resistance per 1,000 ft × amps ÷ 1,000. The tool uses standard wire-gauge resistances and reports the drop as volts and % of supply.", "example": "120 V, 10 A, 100 ft of 12 AWG (1.588 Ω/1000 ft): drop ≈ 3.18 V = 2.6%.", "assumptions": [ "Copper conductors at standard resistances.", "The run is the one-way length (doubled internally).", "Ambient temperature and load power factor are typical." ], "sources": [ { "organization": "Wikipedia", "title": "Voltage drop", "url": "https://en.wikipedia.org/wiki/Voltage_drop" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I calculate voltage drop?", "2 × length × resistance × amps ÷ 1000: 2 × 100 × 1.588 × 10 ÷ 1000 = 3.18 V." ], [ "What is an acceptable drop?", "Under 3% for most circuits; 5% is the NEC limit for feeders in many cases." ], [ "How do I fix too much drop?", "Use a larger gauge wire, shorten the run, or reduce the load." ], [ "Why is the length doubled?", "Current travels out and back — the total conductor length is two times the run." ], [ "Does wire material matter?", "Yes — aluminum has higher resistance than copper; the tool models copper." ], [ "What happens if drop is too high?", "Lights dim, motors overheat and run inefficiently, and equipment can malfunction." ], [ "How do I find the amps?", "Divide watts by voltage (see the watts-to-amps calculator), or use the device's rating." ], [ "What is voltage drop?", "The voltage lost along a wire from resistance — it grows with length and current." ], [ "How do I calculate it?", "2 × length × resistance per 1000 ft × current ÷ 1000 (single-phase)." ], [ "What is the maximum recommended drop?", "Under 3% for branch circuits, 5% total including feeders." ], [ "How do I fix excess drop?", "Use a larger gauge wire, shorten the run, or raise the supply voltage." ] ] }, { "slug": "volume-calculator", "name": "Volume Calculator", "canonical_url": "https://boringtoolskit.com/volume-calculator/", "category": "Everyday Calculators", "description": "Calculate the volume of common 3D shapes.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/surface-area-calculator/", "/circle-calculator/", "/concrete-calculator/" ], "answer": "Calculate the volume of common 3D shapes.", "formula": "Cube: a³. Sphere: (4/3)πr³. Cylinder: πr²h. Cone: (1/3)πr²h. The tool computes the interior space of the chosen shape.", "example": "A sphere with radius 3 has volume (4/3)π × 27 ≈ 113.10. A cylinder with radius 2 and height 5 has volume π × 4 × 5 ≈ 62.83.", "assumptions": [ "The shape is a perfect geometric solid.", "All dimensions are in the same units.", "The result is interior volume (wall thickness ignored)." ], "sources": [ { "organization": "Math Is Fun", "title": "Volume", "url": "https://www.mathsisfun.com/geometry/volume.html" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is volume?", "The amount of 3D space an object occupies — its capacity. A sphere of radius 3 has about 113.1 cubic units." ], [ "How do I find the volume of a cube?", "a³ — side cubed. A 3-unit cube has 27 cubic units." ], [ "How do I find the volume of a sphere?", "(4/3)πr³. Radius 3: (4/3)π × 27 ≈ 113.10." ], [ "How do I find the volume of a cylinder?", "πr²h — the area of the circular base times the height." ], [ "How do I convert cubic meters to liters?", "1 m³ = 1,000 L. A 2 m³ tank holds 2,000 L." ], [ "What is the difference between volume and capacity?", "Volume is the space occupied; capacity is what a container can hold. For practical purposes they use the same math — capacity usually in liters or gallons." ], [ "Do wall thicknesses matter?", "For tanks and pipes, yes — interior volume uses the inner dimensions. The calculator uses the dimensions you enter, so enter interior measurements for capacity." ] ] }, { "slug": "volume-converter", "name": "Volume Converter", "canonical_url": "https://boringtoolskit.com/volume-converter/", "category": "Converters", "description": "Volume converter: gallons, liters, quarts, cups, fluid ounces, milliliters.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "wainscoting-calculator", "name": "Wainscoting Calculator", "canonical_url": "https://boringtoolskit.com/wainscoting-calculator/", "category": "Construction & Measurement", "description": "Wainscoting calculator: panels needed for a wall.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "waist-hip-ratio-calculator", "name": "Waist Hip Ratio Calculator", "canonical_url": "https://boringtoolskit.com/waist-hip-ratio-calculator/", "category": "Health", "description": "Waist to hip ratio calculator: WHR and health risk category.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "waist-to-height-ratio-calculator", "name": "Waist to Height Ratio Calculator", "canonical_url": "https://boringtoolskit.com/waist-to-height-ratio-calculator/", "category": "Health", "description": "Waist-to-height ratio calculator: assess abdominal obesity risk from waist and height.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "walking-calories-calculator", "name": "Walking Calories Calculator", "canonical_url": "https://boringtoolskit.com/walking-calories-calculator/", "category": "Health", "description": "Walking calories calculator: calories burned walking by weight and time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "wallpaper-calculator", "name": "Wallpaper Calculator", "canonical_url": "https://boringtoolskit.com/wallpaper-calculator/", "category": "Construction & Measurement", "description": "Wallpaper calculator: rolls needed from wall area, roll coverage, and pattern waste.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "wash-sale-calculator", "name": "Wash Sale Calculator", "canonical_url": "https://boringtoolskit.com/wash-sale-calculator/", "category": "Finance & Investing", "description": "Wash sale calculator: disallowed loss and adjusted basis after a repurchase.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "water-heater-sizing-calculator", "name": "Water Heater Sizing Calculator", "canonical_url": "https://boringtoolskit.com/water-heater-sizing-calculator/", "category": "Construction & Measurement", "description": "Water heater sizing calculator: first-hour rating from peak hot water uses.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "water-intake-calculator", "name": "Daily Water Intake Calculator", "canonical_url": "https://boringtoolskit.com/water-intake-calculator/", "category": "Health", "description": "Daily water intake calculator: estimate hydration needs from body weight and activity.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "water-pressure-calculator", "name": "Water Pressure Calculator", "canonical_url": "https://boringtoolskit.com/water-pressure-calculator/", "category": "Construction & Measurement", "description": "Water pressure calculator: static pressure from elevation head.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "watts-to-amps-calculator", "name": "Watts to Amps Calculator", "canonical_url": "https://boringtoolskit.com/watts-to-amps-calculator/", "category": "Energy & Electrical", "description": "Convert watts to amps for DC, single-phase AC, or three-phase AC with voltage and power factor.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/electricity-cost-calculator/", "/battery-runtime-calculator/", "/unit-conv/" ], "answer": "Convert watts to amps for DC, single-phase AC, or three-phase AC with voltage and power factor.", "formula": "DC: I = P ÷ V. Single-phase AC: I = P ÷ (V × PF). Three-phase AC: I = P ÷ (√3 × V × PF).", "example": "", "assumptions": [ "Entered watts represent real power.", "Three-phase voltage is treated as line-to-line voltage.", "Efficiency, starting current, harmonics, and code sizing factors are excluded." ], "sources": [ { "organization": "NIST", "title": "SI units: ampere, volt, watt", "url": "https://www.nist.gov/pml/owm/metric-si/si-units" }, { "organization": "OSHA", "title": "Electrical safety", "url": "https://www.osha.gov/electrical" } ], "faqs": [ [ "How do you convert watts to amps?", "Divide power in watts by voltage. For direct current, amps = watts ÷ volts. For single-phase AC, amps = watts ÷ (volts × power factor). For three-phase AC, amps = watts ÷ (√3 × volts × power factor)." ], [ "How many amps is 1,500 watts at 120 volts?", "At 120 V single-phase AC with a typical power factor, 1,500 watts draws about 12.5 amps. The exact figure depends on the power factor and whether the circuit is DC, single-phase AC, or three-phase AC." ], [ "What is power factor and why does it matter?", "Power factor is the ratio of real power to apparent power in an AC circuit, usually between 0 and 1. Because only real power (watts) does useful work, an AC load draws more current at a lower power factor. This calculator includes a power-factor input for AC conversions." ], [ "Can I use this estimate to size wiring or breakers?", "No. The result is a planning estimate and excludes efficiency, starting current, harmonics, and electrical-code sizing factors. Always consult a qualified electrician and local electrical code before sizing conductors, breakers, or equipment." ] ] }, { "slug": "wave-calculator", "name": "Wave Calculator", "canonical_url": "https://boringtoolskit.com/wave-calculator/", "category": "Physics", "description": "Calculate wave speed from frequency and wavelength (v = fλ).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/frequency-to-note-calculator/", "/db-to-volume-calculator/", "/velocity-calculator/" ], "answer": "Calculate wave speed from frequency and wavelength (v = fλ).", "formula": "Wave speed = frequency × wavelength. Units: m/s, Hz, and m.", "example": "A wave at 50 Hz with a 2 m wavelength: speed = 50 × 2 = 100 m/s.", "assumptions": [ "Frequency is in hertz and wavelength in meters.", "The calculation assumes the wave travels in a uniform medium.", "Positive frequency and wavelength are required." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "weather-lookup", "name": "Weather Lookup", "canonical_url": "https://boringtoolskit.com/weather-lookup/", "category": "Everyday Calculators", "description": "Current weather and 7-day forecast for any city worldwide. Temperature, feels-like, precipitation, wind, and UV from Open-Meteo. Private, no account.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/timezone-converter/", "/date-difference-calculator/", "/fuel-trip-cost-calculator/" ], "answer": "Current weather and 7-day forecast for any city worldwide. Temperature, feels-like, precipitation, wind, and UV from Open-Meteo. Private, no account.", "formula": "Pulls live weather from the Open-Meteo API: geocodes the city, then fetches current conditions and a 7-day forecast (temperature, precipitation, wind, and more).", "example": "Searching 'Chicago' shows the current temperature (in °F or °C) and the next 7 days of forecast highs and lows.", "assumptions": [ "The city geocodes successfully.", "Open-Meteo is reachable.", "The forecast is used for planning, not safety-critical decisions." ], "sources": [ { "organization": "Wikipedia", "title": "Weather", "url": "https://en.wikipedia.org/wiki/Weather" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I check the weather?", "Search a city name — the tool shows current conditions and a 7-day forecast from Open-Meteo." ], [ "Is the weather data free/accurate?", "It comes from national weather service models via Open-Meteo — same family of data as major apps, with typical forecast accuracy." ], [ "Does it show warnings?", "No — for severe weather alerts use official services (NWS, national meteorological offices)." ], [ "Why is the forecast different from my app?", "Different apps use different models and update times — small differences are normal." ], [ "Can I switch between °F and °C?", "Yes — the tool has a unit toggle." ], [ "How far ahead does it forecast?", "7 days of daily highs/lows plus current conditions." ], [ "Is my search private?", "Yes — the request goes directly to the geocoding and forecast APIs without an account." ] ] }, { "slug": "weight-converter", "name": "Weight Converter", "canonical_url": "https://boringtoolskit.com/weight-converter/", "category": "Converters", "description": "Weight converter: pounds, kilograms, ounces, grams, and stones.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "weight-loss-timeline-calculator", "name": "Weight Loss Timeline Calculator", "canonical_url": "https://boringtoolskit.com/weight-loss-timeline-calculator/", "category": "Health", "description": "Weight loss timeline calculator: how long a healthy weekly deficit will take.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "weighted-average-calculator", "name": "Weighted Average Calculator", "canonical_url": "https://boringtoolskit.com/weighted-average-calculator/", "category": "Everyday Calculators", "description": "Calculate a weighted average (weighted mean). Enter values and weights to combine scores or grades that count differently.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/statistics-calculator/", "/variance-calculator/", "/percentile-calculator/" ], "answer": "Calculate a weighted average (weighted mean). Enter values and weights to combine scores or grades that count differently.", "formula": "Weighted average = Σ(value × weight) ÷ Σ(weight).", "example": "A student scores 90 on a quiz worth 20% and 75 on a final worth 80%. Weighted average = (90×20 + 75×80) ÷ 100 = (1800 + 6000) ÷ 100 = 78.", "assumptions": [ "The number of values must equal the number of weights.", "Weights must sum above zero.", "Weights are relative and do not need to sum to 100." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "NIST/SEMATECH e-Handbook of Statistical Methods", "url": "https://www.itl.nist.gov/div898/handbook/" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "weighted-grade-calculator", "name": "Weighted Grade Calculator", "canonical_url": "https://boringtoolskit.com/weighted-grade-calculator/", "category": "School & Education", "description": "Weighted grade calculator: final grade from category scores and weights, with letter grade.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "wet-bulb-temperature-calculator", "name": "Wet Bulb Temperature Calculator", "canonical_url": "https://boringtoolskit.com/wet-bulb-temperature-calculator/", "category": "Geography", "description": "Wet bulb temperature calculator: wet-bulb from temperature and humidity (Stull 2011).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "win-loss-percentage-calculator", "name": "Win Loss Percentage Calculator", "canonical_url": "https://boringtoolskit.com/win-loss-percentage-calculator/", "category": "Sports", "description": "Win-loss percentage calculator: winning percentage with ties counted as half a win.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "win-streak-probability-calculator", "name": "Win Streak Probability Calculator", "canonical_url": "https://boringtoolskit.com/win-streak-probability-calculator/", "category": "Gaming", "description": "Win streak probability calculator: odds of winning N games in a row.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "wind-chill-calculator", "name": "Wind Chill Calculator", "canonical_url": "https://boringtoolskit.com/wind-chill-calculator/", "category": "Geography", "description": "Wind chill calculator: feels-like temperature from air temperature and wind speed.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "wind-turbine-output-calculator", "name": "Wind Turbine Output Calculator", "canonical_url": "https://boringtoolskit.com/wind-turbine-output-calculator/", "category": "Energy & Electrical", "description": "Wind turbine output calculator: power from blade size and wind speed.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "window-size-calculator", "name": "Window Size Calculator", "canonical_url": "https://boringtoolskit.com/window-size-calculator/", "category": "Construction & Measurement", "description": "Window size calculator: recommended window area for a room.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "wire-size-calculator", "name": "Wire Size Calculator", "canonical_url": "https://boringtoolskit.com/wire-size-calculator/", "category": "Energy & Electrical", "description": "Wire size calculator: suggested AWG for a current and run length (copper, 3% drop target).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "word-counter", "name": "Word Counter", "canonical_url": "https://boringtoolskit.com/word-counter/", "category": "Text & Developer Tools", "description": "Count words, characters, sentences, and reading time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/keyword-density-calculator/", "/readability/", "/text-case/" ], "answer": "Count words, characters, sentences, and reading time.", "formula": "Word count = tokens split by whitespace (non-empty). Character count = length of the text including spaces. The tool counts instantly as you type or paste.", "example": "'The quick brown fox' = 4 words and 19 characters.", "assumptions": [ "Whitespace separates words.", "Character count includes spaces.", "The count updates on paste and typing." ], "sources": [ { "organization": "Wikipedia", "title": "Word count", "url": "https://en.wikipedia.org/wiki/Word_count" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "How do I count words?", "The tool splits your text on whitespace and counts the non-empty tokens — 'The quick brown fox' is 4 words." ], [ "Does the character count include spaces?", "Yes — it counts the full length of the text, spaces included." ], [ "How long should a meta description be?", "About 150–160 characters to display fully in search results." ], [ "How long should a title be?", "About 60 characters to avoid truncation in search results." ], [ "Why do counts differ across tools?", "Definitions vary: hyphenated words, numbers, and emoji may count as one or more tokens depending on the tool." ], [ "Does it run locally?", "Yes — nothing is uploaded; counting happens in your browser." ], [ "Can I use it for essays with limits?", "Yes — paste your draft and edit until you hit the required word count." ], [ "How does a word counter work?", "It splits text on whitespace and counts the tokens as words." ], [ "Does character count include spaces?", "It can go either way — the calculator shows both totals." ], [ "What is a good meta description length?", "About 150–160 characters so search results don't truncate it." ], [ "How fast do people read?", "Roughly 200–250 words per minute for average content." ] ] }, { "slug": "words-per-minute-calculator", "name": "Words Per Minute Calculator", "canonical_url": "https://boringtoolskit.com/words-per-minute-calculator/", "category": "Time & Work", "description": "Words per minute calculator: typing speed from characters and time.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "work-calculator", "name": "Work Calculator", "canonical_url": "https://boringtoolskit.com/work-calculator/", "category": "Physics", "description": "Work calculator: work done by a force over a distance (W = F \\u00d7 d).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "work-power-calculator", "name": "Work and Power Calculator", "canonical_url": "https://boringtoolskit.com/work-power-calculator/", "category": "Physics", "description": "Calculate mechanical work (W = F·d) and power output (P = W/t).", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/kinetic-energy-calculator/", "/potential-energy-calculator/", "/force-calculator/" ], "answer": "Calculate mechanical work (W = F·d) and power output (P = W/t).", "formula": "Work (W) = force × distance. Power (P) = work ÷ time. Units: joules (J) and watts (W).", "example": "A 300 N force moves an object 4 m in 2 s: work = 300 × 4 = 1200 J; power = 1200 ÷ 2 = 600 W.", "assumptions": [ "Force is in newtons, distance in meters, time in seconds.", "Power uses the time entered; if zero it defaults to 1 s for an instantaneous reading.", "Positive force and distance are required." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "Guide for the Use of the International System of Units (SI)", "url": "https://www.nist.gov/pml/owm/metric-si" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "world-clock", "name": "World Clock", "canonical_url": "https://boringtoolskit.com/world-clock/", "category": "Time & Work", "description": "Compare the current local date, time, UTC offset, and daylight-saving context across selected IANA time zones.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "2026-08-25", "related_urls": [ "/timezone-converter/", "/time-zone-meeting-planner/", "/country-facts/" ], "answer": "Compare the current local date, time, UTC offset, and daylight-saving context across selected IANA time zones.", "formula": "Shows the current time in major world cities and time zones simultaneously, applying each zone's offset and daylight saving rules.", "example": "When it's 9:00 AM in New York, the clock shows 2:00 PM in London and 6:00 AM in Los Angeles (summer).", "assumptions": [ "The system clock is accurate.", "City zones use current IANA offsets.", "Times are read at the moment of viewing." ], "sources": [ { "organization": "Wikipedia", "title": "Time zone", "url": "https://en.wikipedia.org/wiki/Time_zone" }, { "organization": "BoringToolsKit Editorial Team", "title": "Calculation methodology", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [ [ "What is a world clock?", "A display of the current time in major cities and time zones simultaneously." ], [ "How accurate is it?", "As accurate as your device clock — it applies each zone's offset and DST." ], [ "Does it handle daylight saving?", "Yes — zones reflect current DST rules." ], [ "How is it different from the timezone converter?", "The converter finds a specific time in another zone; the world clock shows current times everywhere." ], [ "Can I plan meetings with it?", "Use it for a quick check, then the meeting planner for scheduling." ], [ "Why is the time different in summer?", "Daylight saving shifts some zones; the clock follows." ], [ "What cities does it include?", "Major world cities across the primary time zones — the standard set." ] ] }, { "slug": "xp-level-calculator", "name": "XP Level Calculator", "canonical_url": "https://boringtoolskit.com/xp-level-calculator/", "category": "Gaming", "description": "XP level calculator: total XP needed and progress percentage toward the next level.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "xp-to-level-calculator", "name": "XP to Level Calculator", "canonical_url": "https://boringtoolskit.com/xp-to-level-calculator/", "category": "Gaming", "description": "XP-to-level calculator: experience needed for the next level on linear or quadratic curves.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "yard-feet-converter", "name": "Yard to Feet Converter", "canonical_url": "https://boringtoolskit.com/yard-feet-converter/", "category": "Converters", "description": "Yard to feet converter: yards, feet, inches.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "yarn-weight-converter", "name": "Yarn Weight Converter", "canonical_url": "https://boringtoolskit.com/yarn-weight-converter/", "category": "Converters", "description": "Yarn weight converter: US names to wraps per inch and needle size.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "youtube-revenue-calculator", "name": "YouTube Revenue Calculator", "canonical_url": "https://boringtoolskit.com/youtube-revenue-calculator/", "category": "Social Media", "description": "Estimate YouTube revenue from monthly views and RPM.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/social-media-earnings-calculator/", "/tiktok-money-calculator/", "/video-watch-time-calculator/" ], "answer": "Estimate YouTube revenue from monthly views and RPM.", "formula": "Estimated revenue = (views ÷ 1,000) × RPM. RPM defaults to $2.00 when left blank.", "example": "100,000 views at a $2.00 RPM: (100,000 ÷ 1,000) × 2 = $200.00.", "assumptions": [ "RPM (revenue per 1,000 views) is the user's estimate; actual RPM varies by niche, geography, ads, and monetization status.", "Revenue is gross before platform share and taxes.", "The estimate applies to monetized watch-page views only." ], "sources": [ { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "z-score-calculator", "name": "Z-Score Calculator", "canonical_url": "https://boringtoolskit.com/z-score-calculator/", "category": "Everyday Calculators", "description": "Calculate the z-score (standard score) for a value. Enter the raw score, mean, and standard deviation to see how many SDs above or below the mean it sits.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "authored-methodology", "reviewed": "July 2026", "related_urls": [ "/statistics-calculator/", "/percentile-calculator/", "/standard-error-calculator/" ], "answer": "Calculate the z-score (standard score) for a value. Enter the raw score, mean, and standard deviation to see how many SDs above or below the mean it sits.", "formula": "Z-score = (value − mean) ÷ standard deviation. A positive z means the value is above the mean; negative means below.", "example": "A test score of 88 with a mean of 80 and a standard deviation of 5: z = (88 − 80) ÷ 5 = 1.6, meaning the score is 1.6 standard deviations above the mean.", "assumptions": [ "Standard deviation must be above zero.", "The score is assumed to come from a roughly symmetric distribution for the percentile reading.", "The z-score standardizes a value relative to the mean and spread of its data set." ], "sources": [ { "organization": "National Institute of Standards and Technology", "title": "NIST/SEMATECH e-Handbook of Statistical Methods", "url": "https://www.itl.nist.gov/div898/handbook/" }, { "organization": "BoringToolsKit", "title": "Calculator methodology and reference cases", "url": "https://boringtoolskit.com/methodology/" } ], "faqs": [] }, { "slug": "z-test-calculator", "name": "Z Test Calculator", "canonical_url": "https://boringtoolskit.com/z-test-calculator/", "category": "Statistics", "description": "Z test calculator: z-score for a sample mean vs a known population.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "zip-code-lookup-calculator", "name": "ZIP Code Lookup", "canonical_url": "https://boringtoolskit.com/zip-code-lookup-calculator/", "category": "Converters", "description": "ZIP code lookup: city, county and state for any US ZIP, or ZIPs for a city.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "zip-county-lookup-calculator", "name": "ZIP Code County Lookup", "canonical_url": "https://boringtoolskit.com/zip-county-lookup-calculator/", "category": "Converters", "description": "ZIP code county lookup: county, FIPS code, and population for any US ZIP.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "zip-timezone-calculator", "name": "ZIP Code Timezone Calculator", "canonical_url": "https://boringtoolskit.com/zip-timezone-calculator/", "category": "Converters", "description": "ZIP Code timezone calculator: find the timezone and current local time for any US ZIP.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "zodiac-compatibility-calculator", "name": "Zodiac Compatibility Calculator", "canonical_url": "https://boringtoolskit.com/zodiac-compatibility-calculator/", "category": "Astrology", "description": "Zodiac compatibility calculator: sun-sign match score by element and modality, entertainment only.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "zodiac-element-calculator", "name": "Zodiac Element Calculator", "canonical_url": "https://boringtoolskit.com/zodiac-element-calculator/", "category": "Astrology", "description": "Zodiac element calculator: element, modality, and ruling planet for any sun sign.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] }, { "slug": "zodiac-sign-calculator", "name": "Zodiac Sign Calculator", "canonical_url": "https://boringtoolskit.com/zodiac-sign-calculator/", "category": "Astrology", "description": "Zodiac sign calculator: find your sun sign, element, modality, and ruling planet from a birth date.", "privacy": "Inputs and results stay in this browser unless the page clearly labels an external request.", "evidence_level": "catalogue", "reviewed": "July 26, 2026", "related_urls": [] } ] }