Free Compound Interest Calculator
Watch compounding work its magic. Enter your principal, rate, time and compounding frequency to see your money grow year by year.
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Future value
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Interest earned
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Growth multiple
How to use
- Enter your starting principal, annual interest rate and number of years.
- Choose how often interest compounds — more frequent compounding grows faster.
- See future value, interest earned and a year-by-year table.
Frequently asked questions
What is compound interest?
Interest earned on both your principal and previously earned interest — growth accelerates over time.
How often should interest compound?
More frequent compounding (monthly vs yearly) gives slightly higher returns.
What is the rule of 72?
Divide 72 by your rate to estimate doubling time: at 8%, money doubles in ~9 years.
Is this calculator free?
Yes — free forever, no signup.