Auto Loan Calculator
This free auto loan calculator estimates your monthly car payment from the vehicle price, trade-in value, down payment, sales tax rate, interest rate, and loan term. It shows the amount financed, total interest, and total cost so you can compare offers before you're at the dealership. Nothing you enter is sent anywhere or stored.
How to Use It
- Enter the vehicle price, trade-in value, and down payment.
- Enter your local sales tax rate, the interest rate offered, and the loan term in months.
- The estimated monthly payment and full breakdown update instantly as you change any field.
How It Works
Sales tax is calculated on the vehicle price after subtracting your trade-in value, since most US states apply tax that way. The amount financed is the vehicle price, minus your trade-in value and down payment, plus that sales tax. From there, the monthly payment uses the same standard fixed-rate amortization formula as the Loan and Mortgage Calculators.
Formulas
sales tax = (vehicle price − trade-in value) × sales tax rate ÷ 100
amount financed = vehicle price − trade-in value − down payment + sales tax
monthly payment = amount financed × [r(1 + r)^n] ÷ [(1 + r)^n − 1], where r = annual rate ÷ 12 ÷ 100 and n = number of monthly payments
A worked example: a $27,000 vehicle with a $2,000 down payment, no trade-in, 0% sales tax, a 6% interest rate, and a 60 month term finances $25,000 and comes out to a $483.32 monthly payment, with $3,999.20 in total interest over the life of the loan. Add an $8,000 trade-in and a 7% sales tax rate to that same example, and the taxable amount drops to $19,000, with $1,330 in sales tax added back into the amount financed.
Total cost, shown in the results, is your own cash outlay: the down payment plus every loan payment. The trade-in vehicle's value is a credit against the purchase, not new money spent, so it is not counted toward that figure. Everything runs client-side in your browser. Nothing you enter is sent anywhere or stored.
Frequently Asked Questions
How does the trade-in tax credit work?
In most US states, sales tax on a new vehicle purchase is calculated only on the price after subtracting your trade-in value, not the full vehicle price. For example, trading in a car worth $5,000 against a $20,000 purchase means tax is calculated on $15,000. A minority of states tax the full vehicle price regardless of any trade-in, so check your own state's rule before relying on this figure.
Why does this tool ask me to enter a sales tax rate instead of looking it up?
This site runs entirely in your browser with no backend or server, so it has no way to look up your local combined state and county tax rate automatically. Enter the rate that applies where you'll register the vehicle. If you're not sure, your state's department of motor vehicles website or a recent registration document usually has it.
How is this different from the Loan Calculator?
The Loan Calculator handles a generic loan: an amount, a rate, and a term, plus an optional extra monthly payment for tracking early payoff. This tool is built around the numbers a car buyer actually compares: vehicle price, trade-in value, down payment, and sales tax, and it computes the amount financed from those instead of asking for it directly. It does not include the Loan Calculator's extra-payment or early-payoff tracking, since that is not typically part of comparing dealer offers.
Why is the loan term capped at 96 months?
Ninety six months, 8 years, is longer than nearly any real auto loan offered by lenders. The generic Loan Calculator allows much longer terms since it is not specific to vehicles, but capping this tool at a realistic auto loan length helps catch an accidental typo (entering a term in months when years were intended, for example) rather than silently producing a technically valid but unrealistic result.
Does this include title, registration, or dealer fees?
No. Those fees vary widely by state, county, and dealer, and are not included in this estimate. If you know them, you can approximate their effect by adding them to the vehicle price before entering it.
What if my down payment and trade-in already cover the full cost?
The tool shows a message that no loan is needed rather than attempting to calculate a payment on a zero or negative amount financed. In that situation, you would be paying for the vehicle in full without financing it.