Calculation details
Planning estimate only, not financial, tax, or legal advice. Verify assumptions and current rules before making decisions.
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What does this calculator estimate?
A CD (certificate of deposit) calculator projects what a fixed-term deposit grows to at an annual percentage yield. Enter your deposit, APY, compounding frequency, and term to see the maturity value and interest earned.
- Maturity = deposit × (1 + APY/compounds)^(compounds × years)
- Interest = maturity − deposit
- CDs lock your money for a fixed term
What a CD calculator does
A certificate of deposit is a savings product that pays a fixed APY in exchange for leaving your money for a set term. The calculator compounds your deposit at the chosen frequency to show what it will be worth at maturity.
Limitations to watch for
Withdrawing before maturity triggers an early-withdrawal penalty (often several months of interest), which can erase gains. The APY is fixed at purchase, but renewal rates can be lower. Inflation can outpace the rate, reducing real purchasing power.
How to use it in practice
Compare APYs across terms — a longer term usually pays more but locks your money longer. Build a CD ladder (staggered terms) to keep some money maturing regularly. Only buy a CD if you won't need the cash before maturity.
['Enter the deposit amount.', 'Enter the APY and compounding frequency.', 'Enter the term; the tool compounds to the maturity value.']
How CDs work
A certificate of deposit locks money for a term at a fixed rate. The calculator projects the maturity value from the deposit, rate, and term, with the compounding frequency the bank uses.
Early withdrawal penalties
Withdrawing before maturity triggers a penalty — typically 3–6 months of interest. On a 1-year CD, the penalty can erase most of the yield. The calculator shows the maturity value; check the penalty before committing funds you may need.
CD laddering
Laddering splits money across 3, 6, 12, and 24-month CDs so a rung matures regularly. The calculator's per-CD math applies to each rung.
A worked example
$10,000 at 4.5 percent APY for 12 months: about $10,460 at maturity. At 5 percent: $10,512. The calculator returns the exact maturity value from the bank's compounding.
CDs vs. high-yield savings
CDs lock the rate; savings accounts stay liquid. With rates similar, liquidity often wins — the calculator's yield comparison makes the small difference explicit.
How this calculator works
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.
Worked 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 to verify
- The APY stays constant for the full term.
- Interest is compounded at the selected frequency.
- No withdrawals are made before maturity.
Frequently asked questions
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.
Cite this tool
BoringToolsKit. “CD Calculator.” boringtoolskit.com/cd-calculator/ (reviewed 2026-08-25). Free to reference in articles, syllabi, and answer posts with a link.
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