Calculation details
Planning estimate only, not financial, tax, or legal advice. Verify assumptions and current rules before making decisions.
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Use this result
Share the current inputs or ask ChatGPT to explain the calculation in context.
What does this calculator estimate?
A mortgage payment calculator estimates your monthly payment. Enter the loan amount, rate, and term to see principal, interest, and the full breakdown.
- Payment = P×r×(1+r)^n ÷ ((1+r)^n − 1)
- $300k at 6.5%, 30yr ≈ $1,896/mo
- Add taxes and insurance for the true total
How mortgage payments are structured
The amortization formula spreads the loan into equal monthly payments covering interest plus principal. Early payments go mostly to interest; later ones to principal. The tool shows the payment and total interest over the term.
Limitations to watch for
The estimate is principal and interest only — property taxes, homeowners insurance, and PMI add hundreds per month. The rate and term are fixed here; ARMs adjust. Extra payments shorten the term and cut interest dramatically.
How to use it in practice
Enter the price, down payment, current rate, and term to find the base payment. Add local taxes and insurance for a realistic budget. Test what a rate change or extra payment does to the total interest.
['Enter the loan amount (or price and down payment).', 'Enter the interest rate and term.', 'Read the monthly payment and total interest.']
How this calculator works
Formula
Monthly payment = P × r × (1 + r)^n ÷ ((1 + r)^n − 1), where P is the principal, r the monthly rate (annual ÷ 12), and n the months. The tool also estimates taxes, insurance, and total interest.
Worked example
A $300,000 mortgage at 6.5% for 30 years: about $1,896/month in principal and interest.
Assumptions to verify
- A fixed rate for the full term.
- Equal monthly payments (standard amortization).
- Taxes and insurance are estimated separately.
Frequently asked questions
How do I calculate a mortgage payment?
Use the amortization formula: $300k at 6.5% for 30 years ≈ $1,896/month principal and interest.
What does the payment include?
The tool's base payment is principal and interest. Taxes, insurance, and PMI are extra.
Why is my quote higher?
Lenders add escrow for taxes and insurance, PMI under 20% down, and rate-lock costs.
How much interest will I pay total?
At 6.5% for 30 years on $300k, roughly $382k in interest — the tool shows the exact number.
Should I choose 15 or 30 years?
15-year loans have higher payments but far less total interest; 30-year gives flexibility. Compare both.
How do extra payments help?
Extra principal payments cut the term and the interest — often saving tens of thousands.
What is PMI?
Private mortgage insurance on loans with less than 20% down — added to the payment until you reach 20% equity.
Read the guide
Mortgage Payment Estimates: Principal, Interest, Taxes, and Insurance
Open the guide →Cite this tool
BoringToolsKit. “Mortgage Payment Calculator.” boringtoolskit.com/mortgage-payment-calculator/ (reviewed 2026-08-25). Free to reference in articles, syllabi, and answer posts with a link.
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