Compound Interest Calculator
See how your money grows when interest earns interest. Enter a starting amount, a monthly deposit, a rate and a time period.
Example future balances
How this calculator works
Interest is added to your balance at the compounding interval you choose, and the next interest payment is calculated on the larger balance. We convert your rate into an equivalent monthly rate, then grow the starting balance and add each monthly deposit at the end of the month. Deposits are assumed to be made once a month.
FAQ
What is compound interest?
It is interest calculated on both your original money and the interest already earned. Over many years this makes growth speed up.
Does more frequent compounding matter?
It helps a little. Daily compounding earns slightly more than yearly at the same rate, but the rate and the time matter far more.
Are taxes included?
No. Interest in a taxable account may be taxed. Retirement accounts can change this.
Rates and limits last updated: October 2026. This is an estimate for general information only, not financial, tax or legal advice.