Interest Calculator

Compare simple vs compound growth side by side for any principal, rate and timeframe.

Enter your details and press Calculate to see results.

Formula

Simple: I = Prt · Compound: A = P(1 + r)^t

$10,000 at 6% for 5 years earns $3,000 simple or $3,382.26 compounded — compounding adds $382.26.

The gap between methods widens with rate and time. At low rates over short periods they are nearly identical; over decades compounding dominates.

Which should I use for savings accounts?

Compound — nearly all banks compound daily or monthly.

Estimate monthly mortgage payments including principal, interest, taxes and insurance for any home price.

Work out the monthly payment, total interest and total repayment for any personal or business loan.

Interest that never compounds: principal × rate × time, calculated instantly.

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Watch money grow with compounding — add regular contributions and choose any compounding frequency.

See how long a credit card balance takes to clear at your payment level and what you'll pay in interest.