Simple Interest Calculator
Work out simple interest in seconds: enter the amount, the annual rate and the time, and see the interest, the total and the monthly interest.
How it works
- 1
Enter the principal
The amount borrowed or invested.
- 2
Add rate and time
Annual interest rate and number of years (decimals allowed).
- 3
Read the result
Interest, total amount and interest per month.
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Frequently asked questions
Simple interest is charged on the principal only; compound interest is also charged on previously earned interest.
The simple interest formula
Simple interest is calculated only on the original principal: interest = principal × rate × time. Borrowing 10,000 at 5% for 3 years costs 1,500 in interest, the same amount every year.
Many short-term loans, some bonds and certain savings products use simple interest. Most savings accounts and investments compound, which grows faster — compare both with the compound interest calculator.