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Compound Interest Calculator

Enter initial amount, annual rate, compounding frequency, and term. Optionally add a recurring contribution. See future value, total contributions, and interest earned. Results update instantly.

Runs in your browser. No sign-up. No data sent to any server.

How to use

Enter your initial investment (lump sum), annual interest rate (%), compounding frequency (e.g. monthly), years, and optionally a recurring contribution (e.g. monthly deposit). The calculator shows future value, total you contributed, and interest/growth earned.

Optional. Same period as compounding (e.g. $/month if monthly).

Future value
—

Instant estimate

Total contributions —
Interest / growth —

Assumes constant rate and regular contributions. Actual returns vary.

How compound interest works

With compound interest, earnings are reinvested so you earn on your prior growth. Formula for lump sum: FV = P × (1 + r/n)^(n×t), where P = principal, r = annual rate (decimal), n = compounds per year, t = years. With recurring contributions, each deposit compounds for the remaining periods; the calculator sums the future value of the initial amount plus the future value of an annuity of the recurring deposits.

This tool is for education and planning only. Not investment advice.

Frequently asked questions

What compounding frequency should I use?
Use what matches the product: savings accounts often compound monthly or daily; many investments assume annual. Monthly is a common choice for long-term projections.
Does this work for investments that don't pay fixed interest?
You can use an assumed average annual return (e.g. historical stock market average) as the "rate" for illustration. Returns are not guaranteed.
What period is "recurring contribution"?
It matches your compounding frequency. If you chose monthly compounding, enter the amount you add each month. If quarterly, enter the amount per quarter.

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