How to use this simple interest calculator
Enter the requested values above and select Calculate. The result updates immediately on the page, so you can change one value and compare different scenarios without leaving the calculator.
Formula and method
Example
At 6% simple interest for three years, a $10,000 principal produces $1,800 of interest.
What this calculator is useful for
Calculate interest earned or charged when interest is applied only to the original principal. It is designed for quick estimates and everyday problem solving. When a calculation affects a contract, tax filing, medical decision or other high-stakes situation, verify the result with the appropriate professional or authoritative source.
Frequently asked questions
What does the Simple Interest Calculator calculate?
Calculate interest earned or charged when interest is applied only to the original principal.
How does the calculation work?
Interest = principal × annual rate × time. Total = principal + interest.
Is this calculator free?
Yes. ERICH Calculators is free to use and no account is required.