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Compound Interest Calculator
See how your money grows over time with the power of compounding.
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About Compound Interest
What is compound interest?
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. Einstein reportedly called it the "eighth wonder of the world" — money earns interest on its interest, creating exponential growth over time.
How often should interest compound?
More frequent compounding means slightly more growth. Daily compounding gives marginally more than monthly, which gives more than annual. For most savings accounts and investments, monthly compounding is standard.
What is the Rule of 72?
Divide 72 by your annual interest rate to estimate how many years it takes to double your money. At 7% annual return, your money doubles in approximately 72 ÷ 7 = 10.3 years.