Finance calculator
Compound interest calculator
Project how a starting balance and regular monthly deposits may grow when returns compound over time.
Estimate future value
Adjust each assumption and calculate as often as you like.
Estimated balance
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This is an estimate, not investment advice. Actual returns and fees vary.
How compound interest works
Compound interest adds each period’s return to the balance before the next period is calculated. Regular contributions are also allowed to compound for the time they remain invested.
Future value = principal × (1 + rate ÷ periods)periods × years + future value of recurring deposits
Example
A $10,000 starting balance, $250 monthly contribution, 6% annual rate, and 10-year period produces an estimated future balance. The result separates money contributed from estimated growth so the assumptions are easy to evaluate.
What this estimate leaves out
- Investment fees, taxes, inflation, and changing returns
- Deposits made on dates other than the modeled schedule
- Market volatility and the sequence of actual returns
Method reviewed September 25, 2026. Calculations run locally in your browser. See our calculation methodology.