Compound Interest Calculator
See how your money grows with the power of compounding.
Final Balance
Total Deposited
Interest Earned
Inflation-Adj. Value
Balance Over Time
▶ Year-by-year breakdown
| Year | Deposits | Interest | Balance |
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The Compound Interest Formula
Where A = final amount, P = principal, r = annual rate (decimal), n = compounding frequency per year, t = time in years. Regular contributions are added each compounding period.
Frequently Asked Questions
What is compound interest? ▼
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. It causes your money to grow exponentially rather than linearly.
How often should interest compound? ▼
More frequent compounding means slightly more growth. Daily compounding produces marginally more than monthly, which produces more than annual. The difference is small for typical savings rates but grows with higher interest rates.
What is the Rule of 72? ▼
The Rule of 72 is a quick way to estimate how long it takes to double your money. Divide 72 by the annual interest rate. At 7%, your money doubles roughly every 72 ÷ 7 ≈ 10.3 years.
Why does starting early matter so much? ▼
Starting 10 years earlier can double or triple your final balance. The first dollars invested have the most time to compound. This is why even small contributions in your 20s are more valuable than larger ones in your 40s.