How the math works
Interest = Principal × (Rate / 100) × Time. Amount = Principal + Interest.
Example
- Enter the principal.
- Enter the annual interest rate.
- Enter time in years (decimals allowed).
Catch the catches
- Most modern savings accounts compound. Use the Compound Interest Calculator if interest is added to the balance.
Questions
How is this different from compound interest?
Simple interest is Principal × Rate × Time. Compound interest adds interest to the balance so later interest is calculated on a larger amount.
Are these calculators free?
Yes. They run in your browser. You do not need an account, and we do not require personal financial data to use them.
Should I treat the result as a bank or store quote?
No. Results are educational math. Merchants, lenders, and tax rules can differ. Verify the live terms before you pay.