Calculate simple interest and the ending balance from a principal, annual rate, and time, with a side-by-side compound-interest comparison.
How to use Simple Interest Calculator
Enter the principal and annual interest rate.
Set the time in years, months, or days.
See the interest earned and ending balance.
Frequently asked questions
What is the difference between simple and compound interest?
Simple interest is calculated only on the original principal, while compound interest also earns interest on accumulated interest. This tool shows simple interest plus a compound comparison.