Use the Simple Interest Calculator to find the interest on a principal amount when interest is charged only on that original amount.
How to Use
Enter the principal amount, the annual interest rate as a percentage, and the time in years. Press Calculate to see the simple interest and the total amount to be repaid.
Formula in Plain Words
Multiply the principal by the interest rate and by the time in years, then divide by 100. Add that interest to the principal to get the total amount.
Worked Example
Borrow 1000 at 10% a year for 2 years. The simple interest is 1000 times 10 times 2, divided by 100, which is 200. The total amount is 1200.
FAQs
Is the interest rate annual or monthly?
Annual. Enter 10 for 10% a year, and enter the time in years to match.
How is this different from compound interest?
Simple interest is calculated only on the original principal, so it does not grow on earlier interest the way compound interest does.
Can I use decimals?
Yes. You can enter amounts, rates and times with decimals, such as 2.5 years.