INTERACTIVE TOOL
Compound interest calculator
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How to use this tool
- Enter the initial principal.
- Set the monthly contribution and scenario annual rate.
- Choose the number of years and compare contributions with estimated growth.
Formula or method usedFinal balance = principal × (1+r/n)^(n×t) plus the future value of contributions.
Worked example
With 1000 initially, twelve contributions of 100 and zero interest, the balance is 2200.
Assumptions and limits
A constant rate is an assumption, not a guaranteed return. Inflation, fees and taxes are excluded.
Frequently asked questions
Are contributions made at the start or end of each month?+
The estimate assumes contributions are made at the end of each month.
What happens to my inputs?+
Calculation inputs are processed locally in your browser. Favorites and preferences may be saved on this device. The site may perform separate network requests for live panels; these do not include the values entered into this local calculator. Do not paste secrets into public tools.
How should I check the result?+
A constant rate is an assumption, not a guaranteed return. Inflation, fees and taxes are excluded.