Simple Interest Calculator
Total: 1150
Interest = principal × annual rate ÷ 100 × years
Estimate interest when interest is calculated only on the original principal.
Formula
Interest = principal × annual rate ÷ 100 × years
Worked example
Starting principal: 1000
Annual interest rate: 5 %
Years: 3
With these inputs, the result is **150 **. Total: 1150
How to use this calculator
- Identify the quantity you want to calculate.
- Enter your measurements in the units shown on each field.
- Read the result, which updates as you change the inputs.
- Check the assumptions below before applying the result.
Assumptions and limits
Assumes a constant simple annual rate. Taxes, fees, inflation, and real product terms are excluded.
Precision and checking
Results are rounded for display. Use the most accurate measurements available, and avoid rounding your inputs unnecessarily. Extra decimal places in a result do not make an estimate more reliable.
To check a result, substitute the same input values into the formula shown above. Change one value at a time to understand how the quantity responds.
Frequently asked questions
What assumptions does this calculation use?
Assumes a constant simple annual rate. Taxes, fees, inflation, and real product terms are excluded.
Are my inputs sent to a server?
No. The calculation runs locally in your browser. The result updates as you edit the inputs.
Sources & references
- Compound Interest Calculator — U.S. Securities and Exchange Commission
