Compound Interest Calculator
See how your money grows with compound interest.
What this tool does
This calculator projects how a starting amount grows with compound interest, optionally with regular contributions. It runs in your browser.
How to use
- Enter your principal, annual rate, and number of years.
- Choose how often interest compounds.
- Optionally add a contribution made each period.
- Click Calculate to see the future value and interest earned.
Notes
- Results are estimates and don't account for taxes or fees.
- Everything runs locally — nothing is uploaded.
Frequently asked questions
How is compound interest calculated?
The principal grows by (1 + r/n)^(n·t), where r is the annual rate, n the compounding frequency, and t the years. Contributions are added at the end of each period.
What does 'contribution each period' mean?
It's an amount added every compounding period. With monthly compounding, that's a monthly contribution.
Is anything sent to a server?
No. The calculation runs entirely in your browser.