Compound Interest Calculator
Enter a starting amount, interest rate, time period, and how often interest compounds — plus any regular deposits — and this calculator projects your future balance, total contributions, and interest earned. It runs entirely in your browser: free, instant, and no sign-up.
Enter an amount, rate, and number of years to see how it grows.
Frequently asked questions
Use A = P(1 + r/n)^(nt), where P is the principal, r is the annual rate (as a decimal), n is how many times a year interest compounds, and t is the number of years. With regular deposits, the future value of those contributions is added on top. This tool does all of it for you.
Simple interest is earned only on your original principal, while compound interest is earned on the principal plus all previously earned interest. That compounding is why balances grow faster over time, especially with frequent compounding and a longer term.
Yes, but with diminishing returns. For the same annual rate, compounding monthly or daily yields slightly more than compounding annually, because interest is added to the balance more often. The difference grows with higher rates and longer terms.
It's an estimate using a fixed interest rate and the standard compound-interest formula. Real returns vary, and it doesn't account for taxes, fees, or inflation — so treat the result as a projection, not a guarantee.
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