How do you find the interest rate on a loan?

Enter the loan amount, monthly payment and number of payments. The calculator finds the annual rate that makes those payments exactly repay the loan.

What is the difference between APR and interest rate?

The interest rate is the cost of borrowing the balance. APR adds certain fees into the rate, so it shows a fuller yearly cost and is usually higher.

Why is my calculated rate higher than advertised?

Your payment may include extra costs such as add-ons, fees or insurance rolled into the loan, or the advertised rate may need a better credit score. Check the loan contract for the exact amount financed.

Can I use this for a mortgage?

Yes, for the principal-and-interest part. Leave out property tax, insurance and HOA from the monthly payment, or the rate will come out too high.

It is accurate to within a tiny fraction of a percent for the numbers you enter. Your lender's figure can differ slightly because of rounding, payment timing or fees.

Interest Rate Calculator

Use this interest rate calculator when you know a loan's amount, monthly payment and number of payments but not its rate. It works backwards to find the annual interest rate, plus the total you'll pay and the total interest.

Free · No signup · Instant results · Mobile-friendly

Implied interest rate

Annual interest rate

5.71%

Total paid

$28,800.00

Total interest

$3,800.00

This is the nominal annual interest rate with monthly compounding. A lender's APR can differ when fees are included.

How the interest rate calculator works

A normal loan calculator starts with a rate and finds the payment. This one does the reverse: it searches for the rate that makes your payments exactly pay off the loan.

Solving for r: there's no simple formula for the rate, so the calculator tries a rate, checks whether the payments would repay too much or too little, and narrows in — hundreds of times in a split second — until it lands on the answer.

The result is the nominal annual rate with monthly compounding (the monthly rate × 12), which is how most loan rates are quoted.

APR vs interest rate

Interest rate

The rate charged on the loan balance. It sets your monthly payment and is what this calculator finds.

APR

The annual percentage rate also includes certain fees, such as origination fees, so it is usually a bit higher. Estimate it with the APR Calculator.

Learn more

Read our step-by-step guide on how to find the interest rate on a loan, or test payments at different rates in the Loan Calculator and Mortgage Calculator.

Formula & methodology

Loan amount = Payment × (1 − (1 + r)^−n) ÷ r

r: Monthly interest rate (annual rate ÷ 12)
n: Number of monthly payments

The calculator solves this equation for r numerically.

Total interest = payment × n − loan amount.

Illustrative example

$25,000 car loan at $480 a month for 60 months

Total paid: $480 × 60 = $28,800. Total interest: $28,800 − $25,000 = $3,800.

The rate that makes 60 payments of $480 repay exactly $25,000 is about 5.71% a year.

Hypothetical figures for illustration only.