Interest Rate Calculator

The Interest Rate Calculator determines real interest rates on loans with fixed terms and monthly payments. For example, it can calculate interest rates in situations where car dealers only provide monthly payment information and total price without including the actual rate on the car loan.
Modify the values and click the Calculate button to use
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years months
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Loan Amortization Graph

Payment Breakdown

Interest rate is the amount charged by lenders to borrowers for the use of money, expressed as a percentage of the principal, or original amount borrowed.

This calculator works backward from a known loan amount, term, and monthly payment to determine the nominal annual interest rate being charged — useful for verifying dealer or lender financing offers where the rate itself is not disclosed.