Compound interest calculator
Enter a starting amount, a monthly contribution and an expected annual return to see how compounding grows your money.
Future value—
Total contributed—
Interest earned—
| Year | Balance | Contributed | Interest |
|---|
How this calculator works
It assumes your return compounds monthly and that contributions are added at the end of each month. Real returns vary year to year, and this estimate does not include taxes, fees or inflation.
The formula
Each month, the balance grows by the monthly rate (annual rate ÷ 12), and then the contribution is added. Over long periods, the interest earned on past interest becomes the biggest driver of growth. That's why starting early matters more than the exact amount.
Estimates only. Not financial advice. See our disclaimer.