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 and grow the same way.
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.