Simple Interest Calculator
Work out simple interest in seconds. Enter your principal, the annual interest rate and the number of years, and ToolOrbit shows the interest earned plus the total amount you'll have. Uses the classic I = P·r·t formula — calculated instantly and privately in your browser.
Examples
Principal $1,000, rate 5%, time 3 years
Interest $150.00, Total $1,150.00
How it works
Simple interest is charged on the original amount only: Interest = Principal × Rate × Time ÷ 100, with the rate per year and the time in years. The total is the principal plus that interest.
| Time | Interest | Total |
|---|---|---|
| 6 months (enter 0.5) | 25 | 1,025 |
| 1 year | 50 | 1,050 |
| 3 years | 150 | 1,150 |
Time is entered in years, so convert months by dividing by 12: 9 months is 0.75. Because interest never earns interest, the amount grows in a straight line. Savings accounts and most long loans use compound interest instead, which gives a higher figure over the same period.
How to use Simple Interest Calculator
Why use this tool
Frequently asked questions
Simple interest is calculated only on the original principal, using I = P·r·t ÷ 100. It does not compound, so interest does not earn further interest.
Simple interest applies the rate to the principal alone. Compound interest applies it to the principal plus previously accrued interest, so it grows faster over time.
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