Compound Interest Calculator — Growth with Optional Monthly Deposits
Estimate a future balance from a starting amount, annual rate, term, compounding frequency, and optional month-end deposits.
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How to use it
Enter the starting amount, annual rate, years, compounding frequency, and optional monthly deposit.
Good to know
Monthly deposits are added at the end of each month. Taxes, fees, and inflation are ignored.
See the effect of repeated compounding
Enter a starting amount, annual nominal rate, years, and frequency. With 10,000 at 7% for 10 years compounded monthly and no monthly deposit, the tool calculates 20,096.61 future value, of which 10,096.61 is interest. It applies the rate at the selected number of periods each year.
It is a projection, not an account quote
Monthly deposits are modeled at the end of each month using a monthly rate derived from the selected compounding frequency. The calculation does not include taxes, fees, variable rates, withdrawal timing, inflation, minimum balances, or product terms. Use an institution’s disclosure and your own assumptions for an actual financial decision. For a second illustration of these inputs, see the Investor.gov compound interest calculator.
Frequently asked questions
What is the compound interest formula?
A = P(1 + r/n)^(nt), where P is the principal, r the annual rate, n the compounding periods per year, and t the years.
How much will my savings grow with monthly deposits?
Add a monthly deposit. Each one is compounded from the month it is added.
Does compounding frequency matter?
A little. More frequent compounding earns slightly more at the same annual rate.