Simple Interest Calculator
Estimate interest that does not compound.
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Formula / Calculation Method
Interest = principal × annual rate × years.
Example Calculation
1,000 at 5% for 2 years earns 100 in interest.
Understanding the Result
Uses a constant annual simple-interest rate and fractional years.
What is the Simple Interest Calculator?
Estimate interest that does not compound.
How to Use
Enter the starting principal, annual interest percentage and elapsed time in years. Use a decimal year for part of a year.
Select Calculate after entering your values. Text tools update as you type. Reset restores the starting fields.
Interpreting the Calculation
Simple interest grows in a straight line because past interest does not itself earn interest. The final balance is the principal plus the calculated interest.
Common Questions
How do I enter six months?
Use 0.5 years. Contracts based on actual days may use different day-count conventions.
What assumptions does this tool use?
Uses a constant annual simple-interest rate and fractional years.
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