Car Loan Interest Rate Calculator
Calculate the effective interest rate of your car loan based on loan amount, monthly payment, and loan term.
Published by:
isCalculator Editorial Team
Reviewed by:
Review Board
Last Updated:
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How to use this tool?
This calculator determines the annual interest rate on a car loan based on three inputs:
- Loan Amount ($) – The total amount borrowed.
- Loan Term (months) – The repayment period in months.
- Monthly Payment ($) – Your fixed monthly payment amount.
How to use:
- Enter the loan amount, term, and monthly payment in the provided fields.
- Click the Calculate button.
- The result displays the annual interest rate as a percentage.
Important notes:
- All values must be positive numbers. The monthly payment must be high enough so that total payments exceed the loan amount.
- If an error appears, adjust your inputs accordingly.
- The calculator uses an iterative method to solve for the rate – results are precise to 6 decimal places.
Previous Results
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Frequently Asked Questions
The calculator uses an iterative Newton-Raphson method to solve the loan payment equation for the monthly interest rate, then annualizes it.
You need the loan amount, loan term in months, and the monthly payment amount.
Yes, the calculator works for any fixed-rate amortizing loan with equal monthly payments.
