Compound Interest Calculator

See how your investments grow over time with the power of compounding.

Investment Details

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%
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Results

Final Balance
after years
Total Contributions
principal + deposits
Interest Earned
pure growth
Principal Contributions Interest

Year-by-Year Growth

YearBalanceContributionsInterest EarnedTotal Interest

Compound interest formula: A = P(1 + r/n)^(nt), where P = principal, r = annual rate, n = compounding periods per year, t = time in years.

With monthly contributions, each payment is compounded from the month it's made. This dramatically accelerates growth — contributions made early benefit from more compounding periods.

The Rule of 72: Divide 72 by your interest rate to estimate how many years it takes to double your money. At 7% annual return, your money doubles roughly every 10.3 years.

More frequent compounding (daily vs. annually) has a small but real effect. At 7%, daily compounding yields about 7.25% effective annual rate, vs. exactly 7% for annual compounding.