Simple Interest Calculator
Calculate interest earned without compounding — a fixed percentage of the original principal.
Enter your numbers and select Calculate to see results.
About This Calculator
Simple interest is calculated only on the original principal, unlike compound interest which also earns interest on previously accumulated interest. This calculator computes simple interest for a given principal, annual rate, and time period — commonly used for certain loans, bonds, and short-term calculations.
How This Is Calculated
I = P × r × t
- I
- — Interest earned
- P
- — Principal amount
- r
- — Annual interest rate (decimal)
- t
- — Time in years
$10,000 at 5% simple interest for 3 years earns $1,500, for a total of $11,500.
Assumptions
- Interest is calculated only on the original principal — it does not compound.
Frequently Asked Questions
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Last updated January 15, 2026. Results are estimates for informational purposes only — read our disclaimer.