Compound Interest Calculator
See how a starting amount and regular contributions grow when interest earns interest. Choose the compounding frequency and when contributions go in.
Your plan
Future value
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Growth over time
| Year | Contributed | Interest | Balance |
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How it's calculated
A = P × (1 + r/n)^(n×t) + contributions, each compounded from the date it's added
- The calculator steps month by month using the effective monthly rate (1 + r/n)^(n/12) − 1, so any compounding frequency is handled exactly.
- Results are before tax, fees and inflation. To see real (inflation-adjusted) growth, subtract expected inflation from the rate.
- Rule of 72: divide 72 by the rate to estimate the years it takes to double, e.g. 72 ÷ 8% ≈ 9 years.