Simple Interest Calculator
Calculate simple interest and the final balance from principal, annual interest rate, and a term in years.
Your result
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How to use this calculator
- Enter your values in the labeled fields, keeping the displayed units.
- Choose Calculate or press Enter in a single-line field.
- Review the result and the assumptions below before using it.
Formula and method
Interest = principal × annual rate / 100 × years. Final balance = principal + interest.
Worked example
1,000 at 5% simple interest for 3 years earns 150, making a final balance of 1,150.
What the result assumes
Simple interest does not earn interest on prior interest. Real account and loan contracts may use different day-count rules.
Common question
How is this different from compound interest?
Simple interest is based only on the original principal; compound interest also applies to accumulated interest.