Compound Interest Calculator
See how a lump sum grows over time with compound interest, at any compounding frequency.
Final amount
$1,647.01
- Rate per period0.42%
- Total compounding periods120
- Final amount$1,647.01
- Interest earned$647.01
Inputs used
- Starting amount$1,000.00
- Annual interest rate5 %
- Time invested10 years
- Compounds per year12
About this calculator
Compound interest means you earn interest on your interest: each period, the rate applies to the running balance rather than just the original deposit. Over long horizons this produces exponential growth — the final amount is the starting sum multiplied by (1 + rate per period) raised to the number of periods.
Compounding frequency matters less than people expect: moving from annual to monthly compounding helps, but the big levers are the rate and, above all, time. Doubling the number of years does far more than doubling the compounds per year.
Results are informational only — not financial, medical or legal advice.