Simple Interest Calculator
Calculate simple interest and the total amount from a principal, annual rate, and time in years. Free and accurate.
Independently verified for accuracy
Calculator by Toolsloft ↗- Interest
- 1500
- Total amount
- 11500
This calculator works out simple interest on a principal that does not compound, along with the total you repay or receive. Use it for short-term loans, promissory notes, and many bonds or fixed deposits that pay interest only on the original amount.
How this is calculated
It applies the simple interest formula I = P * r * t, where P is the principal, r is the annual rate as a decimal (rate percent divided by 100), and t is the time in years. The total is the principal plus that interest. Unlike compound interest, no interest is charged on previously accrued interest.
How to use
- Enter the principal amount.
- Enter the annual interest rate as a percentage.
- Enter the time in years, then read the interest and total.
Examples
- $10,000 at 5% for 3 years:
interest $1,500 - $5,000 at 3.5% for 2.5 years:
interest $437.50
FAQ
- How is simple interest calculated?
- Interest = principal times the annual rate (as a decimal) times the number of years. It is charged only on the original principal, never on accrued interest.
- How does simple interest differ from compound interest?
- Simple interest is figured only on the principal, so it grows in a straight line. Compound interest adds earned interest back to the balance, so it grows faster over time.
- Can I use months instead of years?
- Convert months to years first. For example, 18 months is 1.5 years, and 6 months is 0.5 years.