TheCalculatory
Financial · Borrowing & Debt Formula verified

Auto Loan Calculator

Work out your monthly car payment after trade-in value, down payment and sales tax — plus the amount financed and full amortization schedule.

Presets
$
$2k$60k$120k+
$
$0$30k$60k
$
$0$15k$30k
%
0%6%12%
%
0%10%20%
mo
12 mo48 mo84 mo
$ /mo
$0$250$500
On-screen number pad
Tap to type into the highlighted field
Monthly payment
$642.83
60 months payoff time
Amount financed
$32,310.00
83.8% of total paid
Total interest
+$6,259.79
16.2% of total paid
Amount financed Interest
Vehicle price$38,000.00
Trade-in value−$5,000.00
Down payment−$3,000.00
Sales tax+$2,310.00

Step-by-step proofCheck by hand
This is an estimate, not a loan offer. It excludes registration fees, dealer fees, extended warranties and other add-ons, and uses a single flat sales-tax rate rather than your exact state and local rates. Actual financing terms depend on your lender and dealer. Consult a qualified financial professional or your lender before making borrowing decisions.
Visual breakdown

How the balance pays down

Remaining balance Cumulative interest

The solid line is what you still owe; the dashed line is interest paid so far. Auto loans amortize the same way home and personal loans do — early payments are mostly interest.

Year-by-year amortization

How each payment splits between principal and interest
Year Starting balance Principal paid Interest paid Ending balance

How an auto loan payment is calculated

A car loan starts from the negotiated price, not the amount financed. Trade in a vehicle and its value comes straight off the price — and in most states, off the amount sales tax is charged on too, since tax is owed only on what actually changes hands. A down payment reduces the amount financed the same way a trade-in does, but has no effect on the tax, since it is cash rather than a vehicle being exchanged.

Once the amount financed is known, the monthly payment uses the same amortizing-loan formula as any other fixed-rate loan: interest is charged on the remaining balance each month, so early payments are mostly interest and later ones are mostly principal.

A bigger trade-in does double duty
It lowers the amount financed directly, and because most states only tax the price net of trade-in, it lowers the sales tax bill too — a $5,000 trade-in on a $38,000 car can mean several hundred dollars less tax, not just $5,000 less principal.
This does not include dealer fees
Documentation fees, registration, extended warranties and other add-ons are not part of this calculation. Ask for the dealer's full "out the door" price to see everything that would actually be financed.

The formula

M = P × [r(1+r)n] ÷ [(1+r)n − 1]
  • M — monthly payment
  • P — amount financed (price − trade-in − down payment + sales tax)
  • r — monthly interest rate (annual rate ÷ 12), as a decimal
  • n — loan term in months

Worked example

A $38,000 car with a $5,000 trade-in and $3,000 down, at 7% sales tax: tax applies to $38,000 − $5,000 = $33,000, giving $2,310 in tax. Amount financed is $38,000 − $5,000 − $3,000 + $2,310 = $32,310. At 7.2% over 60 months, r = 0.006, n = 60, giving a payment of $642.83 a month — $38,569.79 paid in total, of which $6,259.79 is interest.

Frequently asked questions

How is the amount financed calculated on a car loan?
Start with the vehicle price, subtract the trade-in value and any down payment, then add sales tax. Most states apply a trade-in tax credit — tax is owed only on the price minus the trade-in — so a bigger trade-in lowers both the loan amount and the tax charged on it.
Why are auto loans quoted in months instead of years?
Convention. Auto loan terms cluster around a handful of standard lengths — 36, 48, 60 and 72 months are the most common in the US — so lenders and this calculator quote the term in months directly rather than as a fraction of a year.
Does a longer loan term always cost more overall?
Yes, assuming the same rate. A longer term lowers the monthly payment by spreading the same amount financed over more payments, but more of the balance sits outstanding for longer, so total interest paid goes up. Some lenders also charge a higher rate for longer terms, which compounds the effect.
Does this calculator include fees like registration or dealer add-ons?
No. It covers the amount financed — price, trade-in, down payment and sales tax — and the resulting principal-and-interest payment only. Registration fees, documentation fees, extended warranties and other dealer add-ons are not included and vary by dealer and state.
Sources and method
  • Standard amortizing loan payment formula — general published financial mathematics, identical to the loan and mortgage calculators.
  • Trade-in sales-tax treatment — general description of the trade-in tax credit used by most US states; exact rules vary by state and should be confirmed with your local department of revenue.
  • Amortization schedule computed by month-by-month simulation, which correctly handles any extra principal payments.
Last reviewed: 19 Sep 2026 Sources last verified: 19 Sep 2026 Results use the assumptions explained on this page. Report an error How we check calculations

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