Compound Interest Calculator
Compound interest is interest earned on interest — and over time it adds up fast. Enter your starting amount, the annual rate, and how long you will leave it, and watch your money grow year by year.
More frequent compounding earns slightly more, because interest starts earning interest sooner.
Your result will appear here
Your money after — years
Year-by-year breakdown
| Year | Balance | Interest earned that year |
|---|
A = P(1 + r/n)ⁿᵗ — no extra deposits or withdrawals are included. Actual returns vary with the real interest rate.
How to use
- Enter the amount you are starting with and the annual interest rate.
- Set the number of years and how often interest is compounded, then click Calculate Growth.
- Check the final amount and the year-by-year table to see how compounding builds over time.
Frequently asked questions
What is compound interest?
Compound interest is interest calculated on both your original amount and the interest already earned. That means your balance grows faster each year, because each year you earn interest on a bigger amount.
How is it different from simple interest?
Simple interest only ever pays on the original principal, so it grows by the same amount each year. Compound interest pays on the growing balance, so the yearly gain gets bigger over time.
Does compounding frequency matter much?
A little. Monthly compounding earns slightly more than yearly compounding at the same rate, because interest starts earning interest sooner. The difference is small at low rates and grows with higher rates and longer periods.
Does this include taxes or fees?
No. The calculator shows the gross growth before any tax, fees, or inflation. Real returns will be lower once those are taken into account.