How this works
Simple interest is calculated only on the original principal for the whole term — interest = principal × rate × time ÷ 100, with no compounding. Pick which value you need and enter the other three; it solves for whichever one is missing.
Common questions
Why would anyone use simple interest instead of compound?
Some loan and deposit products (particularly certain short-term or fixed-term instruments) are genuinely structured as simple interest — the point of this calculator is to match that math exactly, not to assume everything compounds.
Can it solve for the interest rate if I know everything else?
Yes — enter the principal, final balance and time, and it works backwards to the implied rate, useful for checking what rate a lender or scheme is actually offering you.