Our free simple interest calculator instantly computes the interest earned on any loan or savings account using the standard formula I = P x R x T. Enter your principal, rate, and time to see your interest breakdown and total balance in seconds.
Total Interest Earned:
Total Balance:
How to Use This Tool
Enter the principal amount (the starting sum of money you are investing or borrowing).
Type in the annual interest rate as a percentage (for example, enter 5 for 5%).
Input the time period in years for your investment or loan.
Click Calculate to see your interest earned and total balance.
The Formula
The calculation uses the standard simple interest formula: I = (P x R x T) / 100 where P is the principal amount, R is the annual interest rate (in percent), and T is the time period in years. Unlike compound interest, simple interest is calculated only on the original principal, so your earnings grow at a steady, predictable rate.
Why It Matters
You lent a friend $10,000 for 3 years at 5% simple interest to help them out. At the end, they will repay $11,500 total. Use this to quickly calculate fair interest for informal loans between friends or family members where compound interest would be too complex.