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Auto Loan Calculator

This calculator turns a vehicle price, down payment, trade-in, sales tax, rate, and term into a monthly car payment. It also totals the interest and the full cost so you can judge an offer before you sign.

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

The lowest rates are only available to the most qualified applicants.

Advertising disclosure: AutoLoanable may receive a referral fee if you apply through the link above. That fee does not change the rate you are offered, and it does not change our content. We are not a lender. Read the full disclosure.

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

How this calculator works

A car loan payment is built from the amount you finance, not the sticker price. The taxable amount is the price minus the trade-in, sales tax is charged on that amount, and the amount financed is the price plus tax minus the down payment and the trade-in.

The monthly payment comes from the standard amortization relationship:

Payment = P × i ÷ (1 − (1 + i)^-n)

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

Multiply the payment by n and subtract P to get the total interest. Total cost adds the down payment and trade-in back to every payment. A 0% loan is simply P split across n months. Enter the rate and sales tax from your own quote; this site is not a lender and does not publish rates.

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 does the calculator work out my car payment?
It applies the amortization relationship Payment = P × i ÷ (1 − (1 + i)^-n). Here i is the annual rate divided by 1,200 and n is the number of monthly payments. Each payment covers that month's interest plus a slice of principal.
Is sales tax charged before or after the down payment?
In most states sales tax is calculated on the vehicle price minus the trade-in, before the down payment is applied. Tax rules vary by state and locality, so check the tax on your own deal.
What rate should I enter?
Use the rate on an offer you have in hand, or a rate you want to test. Pricing moves with credit profile, term, and vehicle, so the number you enter is an assumption, not a quote.
Why does a longer term show more total interest?
A longer term spreads the balance over more months. The payment falls, but interest is charged for longer, so the total interest and total cost usually rise.

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