Compound Interest Calculator
See how a lump sum plus regular contributions grows over time at a given rate of return.
- Starting amount–
- Total contributions–
- Total interest earned–
Growth by year
| Year | Contributions to date | Interest earned to date | Balance |
|---|
How compound interest works
P = starting amount, r = annual rate, n = compounds per year, t = years
Compound interest means you earn returns not just on your original deposit, but on all the interest it has already earned — which is why growth accelerates over long time horizons. Adding regular contributions on top compounds even faster.
More frequent compounding (daily vs. annually) produces slightly higher returns at the same stated annual rate, but the difference is usually small compared to the effect of the rate itself or your contribution amount.
No — it assumes a constant annual return, which real investments (like stock index funds) never actually deliver year to year. Use a conservative average rate to get a realistic long-term estimate, not a guarantee.
For informational purposes only, not investment advice. See our Terms of Use.