Auto Loan Calculator
Estimate a car payment including down payment, trade-in, sales tax and dealer fees.
About this auto loan calculator
The sticker price is only the start of a car loan. Sales tax, title and registration fees and any balance still owed on your trade-in are usually rolled into the amount financed, while your down payment and trade-in value reduce it. This calculator puts all of those together to show the payment and the true total cost.
In many states, including Texas, sales tax is charged on the price minus the trade-in value, which makes trading in worth more than its face value. Rules differ by state, so adjust the tax rate to match where you register the car.
How to use the Auto Loan Calculator
- Enter the vehicle price and your cash down payment.
- Add your trade-in value and anything you still owe on it.
- Enter your state's sales tax rate and estimated fees.
- Choose the APR and term to see the monthly payment and total cost.
How the amount financed is calculated
Financed = price + tax + fees + trade-in owed − trade-in value − down payment
Sales tax here is calculated on the price minus the trade-in value. The monthly payment then uses the standard amortization formula. The total cost of the car adds up every payment plus your down payment and the net value of your trade-in.
Worked example
A $32,000 car with $3,000 down and a $5,000 trade-in, 6.25% tax ($1,687.50 on $27,000) and $500 in fees means financing $26,187.50. At 7% APR for 60 months, the payment is about $518.54 and total interest is roughly $4,925.
Tips for better results
- Get pre-approved by a bank or credit union before visiting the dealer so you can compare their financing offer.
- Longer terms (72–84 months) lower the payment but increase interest and the chance of owing more than the car is worth.
- Negotiate the price, trade-in and financing separately so savings in one aren't hidden by costs in another.
Frequently asked questions
Is sales tax charged before or after the trade-in?
Most states tax the price after subtracting the trade-in, but some tax the full price. Check your state's rules.
What if I owe more than my trade-in is worth?
That negative equity is added to the new loan. Enter the amount owed and the calculator includes it in the amount financed.
Should I choose a 72-month auto loan?
It lowers the monthly payment but usually costs more in interest and leaves you upside down for longer. Use the term selector to compare.
This calculator provides estimates for planning only and is not financial advice. Confirm exact figures with your lender or a licensed professional.
Last reviewed: October 2026 · Results are calculated in your browser.