Compound Interest Calculator
See how your money grows over time with the power of compounding.
Year-by-Year Breakdown
| Year | Starting Balance | Contributions This Year | Interest This Year | Year-End Balance |
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Frequently Asked Questions
What is compound interest?
Compound interest is interest calculated on both your original principal and the interest you've already earned. Unlike simple interest, which only grows your principal, compound interest accelerates growth over time — your interest earns interest.
How often should interest compound?
More frequent compounding produces slightly higher returns. Daily compounding yields more than monthly, which yields more than annual — but the difference is usually small. The rate and time horizon matter far more than compounding frequency.
Does this calculator account for inflation?
No. The results show nominal (not inflation-adjusted) growth. To estimate real returns, subtract your expected inflation rate from the interest rate before entering it.
What is the difference between APY and APR?
APR (Annual Percentage Rate) is the nominal stated rate without accounting for compounding. APY (Annual Percentage Yield) reflects the true annual return after compounding is applied — it is always equal to or higher than APR.
What is the Rule of 72?
Divide 72 by the annual interest rate to estimate how many years it takes for money to double. Example: 6% → ~12 years.
Is my data private?
Yes. All calculations run locally in your browser. No data is sent to any server.