Solve for the interest rate on a loan when you know the amount, the monthly payment, and the term. Reverse-engineer the rate behind any fixed loan or financing offer.
Find the rate from the payment
Sometimes you know the loan amount, the monthly payment, and the term, but not the interest rate — for example, when a dealer or lender quotes only a payment. This calculator solves the amortization equation backward to find the annual interest rate that produces that exact payment. It's the inverse of a normal loan calculator and is useful for checking quotes, comparing financing offers, and spotting hidden costs baked into a "low monthly payment."
For the math to work, the monthly payment must be high enough to repay the loan over the term — at minimum the loan amount divided by the number of months (which corresponds to a 0% rate). If the payment is lower than that, no positive interest rate can amortize the loan, and the calculator will flag it. Once solved, it also shows your total amount paid and total interest.
Enter loan amount, monthly payment, and term to find the implied annual interest rate behind a quoted payment.
Dealers often quote a payment, not a rate. Reverse-solving reveals the real rate so you can compare and negotiate.
The payment must exceed loan ÷ months (the 0% case). Below that, the loan can't be repaid and no rate exists.