Calculate Interest Rate from Payments
Find the interest rate on any loan when you know the payment, amount, and term. Reverse-calculate the APR.
How to Find the Interest Rate
When you know the loan amount, monthly payment, and term but not the rate, this calculator works backwards using binary search iteration to find the APR. This is useful for: dealership financing (where the rate is buried in paperwork), buy-now-pay-later plans, personal loans, and verifying advertised rates match actual payments. If the calculated rate differs significantly from the advertised rate, fees or hidden charges may be inflating your effective rate.
Understanding APR vs Interest Rate
Interest rate is the cost of borrowing the principal. APR (Annual Percentage Rate) includes the interest rate plus fees (origination, closing costs) spread over the loan term. APR is always equal to or higher than the interest rate. A mortgage might have a 6.5% interest rate but a 6.8% APR after fees. By law (TILA), lenders must disclose APR — always compare APR, not just interest rates, when shopping for loans.
Interest rate calculator captures users who are suspicious about their loan terms — a very high-intent audience. These users often explore multiple financial calculators in a session, driving excellent page-per-session metrics. CPC is strong at $5-10 from lending advertisers.
