Finance · Growth over time

Compound interest calculator

See how a principal grows with compounding, plus optional regular contributions.

Investment details

Future value
—
Principal, contributions and interest combined
Total contributed—
Total interest earned—

Rough sheet

step-by-step
Simple Interest Calculator Mortgage Calculator Loan Calculator Percentage Calculator

How compound interest is calculated

Compound interest grows a principal amount by adding interest at regular intervals, then earning interest on that interest going forward — the classic "interest on interest" effect. This calculator applies your chosen compounding frequency (monthly, quarterly, or annually) across your time horizon, and adds any recurring contributions you enter at each compounding step before calculating the next round of interest.

Frequently asked questions

Yes — enter a monthly contribution amount and it’s added to the balance each period before compounding, alongside your initial principal.

You can choose the compounding frequency (e.g. monthly, quarterly, annually) — the calculator adjusts the periodic rate accordingly.