Everyday
Simple Interest Calculator
Calculate simple interest and final balance from principal, annual rate, and time.
- Free to use
- Runs in your browser
- Level B · Industry formula
- Last reviewed 2026-08-16
How to use this calculator
Enter the requested values and select Calculate. The result is computed locally in your browser using the formula shown on this page.
Understanding the result
Estimate interest when interest is calculated only on the original principal.
Calculation method
Interest = Principal × Rate × Time; Balance = Principal + Interest.
Calculator guide
About the Simple Interest Calculator
Estimate interest when interest is calculated only on the original principal.
What to keep in mind
- The rate is entered as an annual percentage.
- This is simple interest, not compound interest.
- Fees and taxes are not included.
Formula & methodology
Interest = Principal × Rate × Time; Balance = Principal + Interest
Review standard: Level B · Industry formula. How calculator reviews work.CalculateMeasure performs the arithmetic locally in your browser. The displayed result depends on the values and units you enter.
Frequently asked questions
What does this calculator calculate?
Estimate interest when interest is calculated only on the original principal.
Can I use the result for an important decision?
Use the result as a calculation aid and verify the inputs, assumptions, and applicable professional or regulatory requirements before relying on it for an important decision.
Does CalculateMeasure store the values I enter?
This calculator performs its arithmetic in your browser. The calculator itself does not need to send your entered values to a server to produce the result.