About the Auto Loan Calculator
This auto loan calculator works out the monthly payment on a new or used car loan from the vehicle price, your down payment, trade-in value, interest rate (APR) and loan term. It also handles the parts dealers often fold into the loan — sales tax, documentation and registration fees, and any balance you still owe on your trade-in (negative equity).
Use it before you visit a dealership so you know what payment a given price and rate should produce, to compare a 48-month loan with a 72-month one, or to check whether a finance manager’s quote adds up. The results show the amount financed, total interest, and the full cost of the car once every payment, your down payment and trade-in are counted.
Sales tax is applied to the price minus the trade-in value, which is how most US states tax vehicle purchases. If your state taxes the full price, set trade-in to zero for the tax and subtract it from the down payment instead. Payments assume a fixed-rate, simple-interest installment loan with equal monthly payments.
With the default inputs, the monthly payment is $649.91. Change any value above to recalculate instantly.
How to use the auto loan calculator
- 1Enter the negotiated vehicle price and your cash down payment.
- 2Add your trade-in value and anything you still owe on that car.
- 3Enter the APR from your lender or dealer quote and choose a loan term.
- 4Enter your local sales tax rate and fees, and choose whether they go into the loan.
- 5Compare the monthly payment with the total interest and adjust the term or down payment.
Formula and method
The amount financed (L) is the vehicle price minus your down payment and trade-in value, plus any payoff still owed on the trade-in and, if you roll them in, sales tax and fees. Sales tax is charged on the price minus the trade-in value.
The monthly payment uses the standard installment-loan formula, where r is the APR divided by 12 and n is the number of monthly payments. Total interest is the sum of all payments minus the amount financed. With a 0% APR the payment is simply the amount financed divided by the number of months.
- M
- Monthly payment
- L
- Amount financed
- r
- Monthly interest rate (APR ÷ 12 ÷ 100)
- n
- Loan term in months
Worked examples
$35,000 car, $5,000 down, 6.9% for 60 months
Tax at 6% on $35,000 is $2,100. Adding that and $800 of fees to the $30,000 left after the down payment gives $32,900 financed. At 6.9% over 60 months the payment is $649.91 and interest totals about $6,095.
Used car with a trade-in, 48 months
The $6,000 trade-in lowers the taxable amount to $22,000, so tax is $1,540. Financing $21,040 at 5.5% for four years costs $489.32 a month and about $2,447 in interest.
Rolling $4,000 of negative equity into a 72-month loan
The trade is worth $10,000 but $14,000 is still owed, so $4,000 is added to the new loan. With tax and fees the amount financed is $51,900 — more than the car’s price — and interest over six years reaches about $14,534.
0% APR promotional financing
With 0% APR the $24,000 balance is simply divided over 60 months, giving $400 a month and no interest at all.
Frequently asked questions
What is a good interest rate for a car loan?+
Rates depend mainly on your credit score, whether the car is new or used, and the term. Borrowers with excellent credit typically get the lowest advertised rates, while subprime borrowers can pay well into double digits. Get a pre-approval from a bank or credit union before visiting the dealer so you have a rate to compare.
Is a 72- or 84-month car loan a bad idea?+
Longer terms lower the monthly payment but increase total interest and usually carry higher rates. Because cars depreciate quickly, long loans also make it more likely you will owe more than the car is worth for several years, which is a problem if you need to sell or the car is totaled.
Should I roll sales tax and fees into my car loan?+
Rolling them in means you pay interest on them for the whole term and start with less equity. Paying tax and fees in cash lowers the amount financed and total interest, so do it if you can afford to without draining your emergency fund.
Does a trade-in reduce sales tax?+
In most US states the trade-in value is subtracted from the price before sales tax is calculated, which can save hundreds of dollars. A few states, including California, tax the full price regardless of a trade-in, so check your state’s rules.
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. A larger down payment reduces the loan, the interest and the risk of being underwater on the loan as the car depreciates.
Results are estimates for educational purposes and are not financial advice. Rates, fees and terms vary — confirm with your lender or a licensed advisor before making decisions.
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