Compound Interest Calculator

Project how an initial balance and recurring contributions may grow when earnings are reinvested over time.

Method and required inputs

Enter a starting balance, contribution schedule, time horizon, estimated return, and compounding frequency. Test lower returns and higher contributions instead of relying on one optimistic projection.

The projection grows the starting balance and each recurring contribution using the selected annual return, compounding frequency, and time horizon. Contributions made earlier have more periods to earn returns, so contribution timing can change the ending value even when the annual total is identical.

Read the complete result

Separate the amount contributed from estimated growth. That distinction shows whether the plan depends primarily on disciplined saving or on an aggressive return assumption. Compare annual, monthly, and beginning-versus-end contribution timing only when the account actually follows that convention.

Run a stress case

Run lower-return, delayed-contribution, and missed-contribution cases. For a long horizon, a small change in return produces a large difference because the assumption compounds repeatedly. Use nominal or inflation-adjusted figures consistently rather than mixing them.

Limits and verification

Investment returns are not fixed interest and can be negative. The estimate does not automatically include taxes, fees, inflation, contribution limits, or withdrawal rules. Confirm account-specific restrictions and avoid treating a projected balance as guaranteed.

This calculator is educational, not a quote, approval, guarantee, tax opinion, or individualized recommendation. Confirm material figures, current rules, and actual product terms before acting.

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