How compound interest comparison calculator works
This calculator compares up to three savings or investment scenarios side by side so you can see which combination of principal, rate, compounding, horizon, and recurring deposit wins. Enter one scenario per line as label | principal | rate% | years | compounding-per-year | contribution | freq | timing, then press Compare.
Each scenario uses the standard compound-interest formula A = P(1 + r/n)^(nt) for the principal, plus the future value of a series for the recurring deposit. Deposits at the start of each period use the annuity-due form (multiplied by (1+r)); deposits at the end use the ordinary-annuity form. The effective annual percentage yield (APY) is (1 + r/n)^n - 1, which lets you compare rates fairly across different compounding frequencies.
The result shows the final balance, total contributions, total interest, and effective APY for every scenario, and highlights the one with the highest final balance. It is a planning estimate, not financial advice — real returns vary. Everything runs in your browser.