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Car Loan Interest Calculator

Enter the amount financed, the interest rate, and the term to see the total interest on a car loan. The tool also shows the monthly payment and how large the interest is relative to the amount borrowed.

By the AutoLoanable Editorial Team · Last updated 2026-09-17

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Enter your numbers and press Calculate. Nothing you type leaves your browser.

How this calculator works

Interest is the cost of borrowing on top of the principal. This tool totals it for a fixed-rate car loan.

Payment = P × i ÷ (1 − (1 + i)^-n), and total interest = payment × n − P

  • P — the amount financed
  • i — the monthly rate, the annual rate divided by 1,200
  • n — the number of monthly payments

Interest as a share of principal divides the total interest by P. At 0% the share is 0 and the total paid equals the amount borrowed. Enter the rate you were offered.

What changes your result

Only a few inputs move the number materially. In rough order of impact:

Sensitivity of the monthly payment
InputEffect on the paymentEffect on total cost
Amount financedDirectly proportionalDirectly proportional
Interest rate / APRDirectly proportionalDirectly proportional
Term (months)Lower payment when longerHigher total interest when longer
Down paymentLowers the paymentLowers total interest
Trade-in equityLowers the amount financedLowers total interest
Sales tax and feesRaises the amount financedRaises total cost

Enter the rate you were actually offered. This site is not a lender and does not publish rates — a quoted rate is only meaningful next to the term and the amount financed.

Frequently asked questions

How is car loan interest calculated?
Interest is charged each month on the balance that is still outstanding. Early payments are mostly interest because the balance is largest; later payments are mostly principal.
What makes total interest go up?
A higher rate, a larger amount financed, or a longer term all raise the total interest. The term matters because interest is charged for more months.
Is interest the only cost of a car loan?
No. Sales tax and fees may be financed, and there can be up-front charges. The total cost calculator adds those, and the APR calculator shows how a fee lifts the yearly cost.
What if the rate is 0%?
At 0% there is no interest. The payment is the amount financed divided by the number of months and the total paid equals the amount borrowed.

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