Free Online Tool
Compound Interest Calculator
Estimate compound interest for savings or investments using an annual return assumption.
The result will appear here.
How to Use
- Enter principal and annual rate.
- Enter period and optional monthly contribution.
- Check final amount and interest.
Examples
- 10,000,000 at 5% for 10 years
- Add 300,000 monthly and calculate long-term growth
Calculation and Conversion Notes
This calculator uses monthly compounding. The monthly rate is converted from `annual rate / 12`. Each month, the monthly rate is applied to the balance, then the monthly contribution is added to get the next month's balance. The simple compound formula is `final amount = principal × (1 + rate)^period`, and interest is calculated as `final amount - principal`.
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