Auto Loan Calculator
Car payment with trade-in, sales tax and fees, and the true total cost.
How to use Auto Loan Calculator
- Enter the vehicle price, your down payment and any trade-in (and what you still owe on it).
- Set your local sales tax rate, the fees, the APR you were offered and the term.
- Read the monthly payment and the total cost, and compare terms: longer loans cost less per month and more overall.
How it works
Amount financed = price − down payment − trade-in equity + sales tax + fees, where trade-in equity is the trade-in value minus what you still owe on it (negative equity is added to the loan). The payment then follows the standard loan formula M = P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1) with a monthly rate r = APR ÷ 12.
Sales tax is your rate × the taxable amount. Most US states tax the price after subtracting the trade-in; a few (for example California and Virginia) tax the full price. Untick the box if your state taxes the full price. Rates and rules change, so the rate is yours to enter.
"Total cost of the vehicle" adds everything you pay: down payment, trade-in equity given up, all loan payments, and tax and fees paid upfront if you did not add them to the loan.
Example
A 30,000 car with 3,000 down and an 8,000 trade-in on which 2,000 is owed, 7% tax on the difference and 500 fees: tax is 7% × 22,000 = 1,540, so the amount financed is 30,000 − 3,000 − 6,000 + 1,540 + 500 = 23,040. At 7% APR over 60 months the payment is 456.21.
Frequently asked questions
How is a car loan payment calculated?
From the amount financed, the APR and the number of months, with the standard loan formula shown above. Interest is charged monthly on the remaining balance.
Is sales tax charged before or after the trade-in?
In most US states the trade-in value is subtracted first, which lowers the tax. Some states tax the full price. Use the checkbox to match your state, and confirm with your DMV or dealer.
Is a longer loan term cheaper?
Per month, yes; in total, no. Going from 60 to 84 months lowers the payment but adds interest and keeps you owing more than the car is worth for longer.
What if I owe more on my trade-in than it is worth?
Enter both numbers. The shortfall (negative equity) is added to the new loan, which the "Amount financed" line shows.
Does this include insurance, fuel or maintenance?
No. It covers buying and financing only.
Limitations
- Simple-interest loans with equal monthly payments only; leases and balloon contracts are not covered.
- Dealer add-ons, rebates and documentation fees vary; enter them in fees or adjust the price.
- For information only. It is not financial advice and not an offer of credit.
Last reviewed November 9, 2026. How we build and test tools.