Compound Interest

Watch savings compound over time

Start with a deposit, add a monthly contribution, and see what it grows into — with the interest earned separated from what you put in.

Interest compounds monthly; contributions are added at the end of each month.

Why compounding matters

Compound interest pays interest on your interest: each month's growth is calculated on the full balance, contributions and past interest included. The effect is small at first and dramatic over decades — doubling your time horizon far more than doubles the interest earned. This calculator is for illustration; real investment returns vary year to year.