Simple Interest Calculator
Calculate interest charged on the original principal without compounding.
Your result
FINANCIALEnter your values and select calculate.
On this page How it works & practical examples
How to use the Simple Interest Calculator
Simple interest uses the starting principal every time, so accrued interest does not itself earn interest. Enter time in years; six months can be represented as 0.5 years. Compare this tool with the Compound Interest Calculator to see the effect of earning interest on interest. A dollar difference should be interpreted alongside whether the product actually uses a simple-interest convention.
The calculation
Worked example
$10,000 at 5% simple annual interest for three years earns $1,500. Principal plus interest is $11,500.
Assumptions and limits
This calculator does not model installment repayments, daily accrual dates or changing principal. A simple-interest loan with periodic principal repayments will not charge the same amount as this unchanged-balance example. The result excludes fees and tax. All displayed monetary amounts are in USD; the arithmetic also applies to another currency if all amounts use the same unit.
Common questions
Can I calculate less than one year?
Yes. Enter a fraction of a year, such as 0.25 for three months, if that matches the agreement’s time convention.
Is this an amortized loan payment?
No. It calculates interest on one unchanged principal. Use Loan Calculator for equal monthly repayments.