Category: Calculators
Simple Interest Calculator
Calculate interest that accrues only on the original principal
Enter a principal, an annual interest rate and a number of years to see the interest earned and the total amount, using simple (non-compounding) interest. Runs entirely in your browser.
Simple interest accrues only on the original principal — unlike compound interest, it never earns interest on interest.
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What this tool does
Simple interest is calculated only on the original principal for the whole term, unlike compound interest, which also earns interest on interest already added to the balance. It is the formula behind many short-term loans, bonds and back-of-envelope estimates: interest = principal × rate × time.
How to use it
- Enter the principal amount.
- Enter the annual interest rate as a percentage.
- Enter the number of years to see the interest and total.
Privacy
This tool runs entirely in your browser. Your input is never uploaded, stored or shared — closing the tab removes it.
Frequently asked questions
- How is simple interest different from compound interest?
- Simple interest is always calculated on the original principal only. Compound interest recalculates interest on the growing balance, so it earns more over time for the same rate.
- Can I use a rate with decimals, like 4.5%?
- Yes. The rate field accepts decimal values.
- Is this financial advice?
- No. This is a plain arithmetic calculator; consult a qualified advisor for real financial decisions.