Compound interest calculator

See how a starting amount and monthly deposits grow when interest earns interest.

Starting amount

What you put in today. 0 is fine.

Monthly deposit

Added at the end of every month.

Interest rate or return

The APY of a savings account, or an assumed return. Investment returns are never guaranteed.

Years

From 1 to 60.

Compounding

Most savings accounts compound daily or monthly.

Press Calculate to watch it grow

Starting values: $5,000 starting deposit, the amount used in the St. Louis Fed's compound interest examples (Sep 12, 2018); $200 a month is an example amount; 4% a year reflects the 'around 4% or higher' APYs NerdWallet says many online banks offer, versus the FDIC national average savings rate of 0.38% (NerdWallet citing FDIC, Oct 2026); 10 years is an example period. Interest compounds monthly with deposits at the end of each month. Rates change and are not guaranteed; investments can lose value. General information, not financial advice. Before taxes and fees, our calculation.