Auto Loan Calculator
Calculate your monthly car payment, total interest, and total cost for any auto loan — new or used.
What is Auto Loan Calculator?
Before you sign at the dealership, run the numbers yourself. This auto loan calculator accounts for the cash down payment, a trade-in, state sales tax (levied on the purchase minus trade-in in most U.S. states), the APR, and the loan term to give you your true monthly payment and total interest.
Dealers often focus you on a "comfortable monthly payment" and quietly extend the loan term to get there. Stretching from 60 to 84 months makes the car feel cheaper but can easily add thousands of dollars in interest and put you underwater for years.
Formula
The amount financed equals the out-the-door price minus any cash and trade-in:
Amount financed = price + (price − trade-in) × sales tax − down payment − trade-in
The monthly payment uses the standard amortization formula:
Payment = P × r × (1 + r)n ÷ ((1 + r)n − 1)
Where P is the amount financed, r is the monthly rate (APR ÷ 12 ÷ 100), and n is the number of months.
Worked example
A new vehicle priced at $35,000, with $5,000 down, no trade-in, 6.5% state sales tax, 7.5% APR over 60 months:
- Sales tax = $35,000 × 6.5% = $2,275
- Amount financed = $35,000 + $2,275 − $5,000 = $32,275
- Monthly payment ≈ $647
- Total interest ≈ $6,527
How to use this calculator
- Enter the negotiated vehicle price (not MSRP).
- Enter your cash down payment.
- If trading in a vehicle, enter what the dealer is giving you for it.
- Enter your state or local sales tax rate.
- Enter the APR and term the lender quoted. Try a few scenarios — 48, 60, and 72 months — to see how the payment and total interest change.
Frequently asked questions
How much should I put down on a car?
A common guideline is 20% down on a new car and 10% on a used car. Putting more down reduces your monthly payment, total interest, and the risk of going underwater (owing more than the vehicle is worth). Some lenders require at least 10% for competitive rates.
Is a longer loan term a good idea?
Rarely. 72- and 84-month auto loans make monthly payments look attractive but you pay substantially more interest and stay underwater longer. If you cannot afford a vehicle on a 60-month loan, consider a cheaper vehicle or a certified pre-owned model.
Does the calculator include taxes and fees?
It includes sales tax on the taxable amount. It does not include title, registration, documentation ("doc") fees, or optional add-ons like extended warranties and gap insurance. Ask the dealer for the "out-the-door" price in writing so nothing is hidden.
Should I get pre-approved before going to the dealership?
Yes. A pre-approval from your credit union or bank gives you a benchmark rate to negotiate against. Dealer financing can be competitive, but you need a number to compare it to. Pre-approvals typically last 30–60 days.
What credit score do I need for the best auto loan rate?
Borrowers with FICO scores above 720 qualify for the lowest advertised APRs. Scores below 620 are considered subprime and will see meaningfully higher rates. Checking your credit (free at annualcreditreport.com) before shopping lets you fix errors in advance.