Simple Interest Calculator

Simple interest is charged only on the original amount. Enter a principal, rate and number of years to see the interest and total.

Last updated: · Reviewed by The CalcWise Team

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How to use this calculator

  1. Enter the principal — the original amount borrowed or invested.
  2. Add the annual interest rate and the time in years.
  3. Calculate to see the simple interest and the total amount.

How it works

Simple interest uses the formula Interest = Principal × Rate × Time. Unlike compound interest, it is never charged on previously earned interest, which makes it easy to calculate and predict.

Simple interest appears in some short-term loans, car loans, and bonds. For savings and most long-term loans, compound interest applies instead — and the difference grows large over time.

Example: $10,000 at 5% simple interest for 3 years earns exactly $1,500 in interest, for a total of $11,500.

Frequently asked questions

When is simple interest used?
It is common in some auto loans, short-term personal loans, and certain bonds, where interest does not compound.
Is simple or compound interest better for me?
As a saver, you want compound interest. As a borrower, simple interest is usually cheaper because it does not charge interest on interest.