Simple Interest Calculator
Calculate simple interest and the final amount on a principal
Simple interest
Calculates simple interest — interest on the original principal only, with no compounding — and the final total. Common for short-term loans, bonds, and quick estimates. Calculated locally in your browser.
FAQ
What's the formula?
Interest = Principal × Rate × Time ÷ 100, where rate is per year and time is in years. The total is principal plus interest.
How is this different from compound interest?
Simple interest is charged only on the original principal. Compound interest is charged on principal plus accumulated interest, so it grows faster — use the Compound Interest Calculator for that.
Can time be a fraction of a year?
Yes. Enter 0.5 for six months, 1.25 for fifteen months, and so on.