How to use this calculator
Enter your initial investment, contribution amounts, interest rate, compounding frequency, and investment length. Optionally add a tax rate on interest income and an inflation rate for real-value estimates. Click Calculate to see your ending balance, total interest earned, and full accumulation schedule.
Compound Interest Calculator
Calculate how your savings grow over time with compound interest. Supports periodic contributions, tax on interest, and inflation adjustment.
About Compound Interest Calculator
About Compound Interest
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. Unlike simple interest, which is calculated only on the principal, compound interest grows exponentially over time — often described as "interest on interest."
Compounding frequency determines how often interest is added to the balance. The more frequently interest compounds, the faster the balance grows. Daily compounding yields slightly more than monthly, which yields more than annual.
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. For example, at 6% interest, your money doubles in approximately 72 ÷ 6 = 12 years.
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Compound Interest Tips
- →Start early — doubling your investment time has a far greater impact than doubling your rate.
- →Daily compounding earns slightly more than monthly, which earns more than annual.
- →Even small monthly contributions dramatically increase the ending balance over 20+ years.
- →Use the Rule of 72: divide 72 by your rate to estimate years to double your money.
Calculate investment returns with 5 solve modes: FV, PV, Rate, N, and PMT.