Compound Interest Calculator
Estimate growth over time. Add optional monthly contributions to model realistic saving and investing.
New to compounding? Start with what compound interest means, then plug your numbers into the calculator. Understand the formula. Compare compound vs simple interest.
Estimated final value
$ —
Total contributed
$ —Total interest earned
$ —What this calculator assumes
- Rate stays constant (real life rates can change).
- Contributions are monthly and start immediately (simple model).
- Results are estimates for education, not financial advice.
Tip: If you’re just comparing two options, try the simple interest calculator as a baseline.
Understanding your results
The estimated final value is the ending balance after interest and (if used) monthly contributions. Total contributed is how much you put in over time. Total interest earned is the difference between the final value and your contributions.
- If you change compounds per year, the result usually moves slightly—time and contributions typically matter more.
- Try increasing the years first to see how compounding accelerates over longer periods.
- Use the compound vs simple interest guide to understand when each model applies.