How to use the Auto Loan Calculator
- Enter the vehicle price, your down payment and any trade-in value.
- Enter the sales tax rate and the interest rate from your lender.
- Pick a term and read the monthly payment, total interest and total cost.
How it works
The amount you borrow is the price, minus your down payment and trade-in, plus sales tax. In many US states sales tax is charged on the price after the trade-in is taken off, which is how this calculator works; a few states tax the full price, so check your state's rule. Dealer, title and registration fees are not included.
A longer term lowers the monthly payment but increases the total interest, and cars lose value quickly, so on long loans you can owe more than the car is worth for several years.
Formula
Amount financed = price − down payment − trade-in + sales tax Monthly payment = A × r(1 + r)ⁿ ÷ ((1 + r)ⁿ − 1)
Example
A $34,000 car with $4,000 down, a $3,000 trade-in and 7% sales tax ($2,170) leaves $29,170 to finance. At 6.9% for 60 months the payment is $576.23. Over 48 months it is $697.16 with $4,294 interest; over 72 months it is $495.92 with $6,536 interest.
Frequently asked questions
Is a 72-month car loan a good idea?
It lowers the payment but costs more interest and increases the time you may owe more than the car is worth. Compare the total cost, not just the monthly figure.
How much should I put down on a car?
Many guides suggest about 20% on a new car and 10% on a used car, which helps avoid owing more than the car's value.
Does my credit score change the rate?
Yes. Lenders set rates largely by credit history, so getting a pre-approval from a bank or credit union before visiting the dealer helps you compare offers.
Does this work for leasing?
No. Leases are priced on depreciation and a money factor, which work differently from a loan.
Last reviewed October 20, 2026. Spotted an error? Tell us.