Auto loan calculator
Estimate a car payment from price and financing terms.
- Formula and assumptions shown
- Table and CSV export
- Runs in your browser
How it works
The calculator builds an estimated amount financed from the vehicle price, entered sales-tax rate, down payment, trade-in credit, and fees. It then applies the fixed-rate amortization model.
Taxable vehicle amount = max(price − trade-in value, 0); excess trade-in = max(trade-in value − price, 0); amount financed = max(taxable amount × (1 + sales-tax rate) + entered fees − down payment − excess trade-in, 0); payment follows fixed-rate amortization.
Taxes and fees are deliberately inputs rather than local estimates. Compare the payment, total interest, and amount financed with the written offer before signing.
Assumptions
- The entered sales-tax rate is applied to vehicle price less trade-in value, with the taxable amount floored at zero.
- Fees are added; the down payment and any trade-in value above the vehicle price are subtracted from the amount financed, which is floored at zero. If they exceed the total cost, the result says nothing is financed and shows the unused amount.
- The rate is fixed and payments are monthly.
- Local trade-in tax treatment, title, registration, insurance, changing rates, and fees not entered are excluded.
Worked example
$35,000 price with a $3,000 trade-in
With a $5,000 down payment, 7% sales tax after subtracting trade-in, and $1,000 fees, the modeled amount financed is $30,240. At 7% for 60 months, the monthly payment is about $598.79.
Step by step
- Subtract the trade-in from the price. $35,000 − $3,000 = $32,000 of taxable vehicle amount.
- Apply the sales tax rate. $32,000 × 7% = $2,240 of sales tax.
- Build the amount financed. $32,000 + $2,240 tax + $1,000 fees − $5,000 down payment = $30,240.
- Compute the payment. The monthly rate is 7% ÷ 12 = 0.5833% over 60 months: $30,240 × 0.0058333 × 1.41763 ÷ 0.41763 = $598.79 a month.
- Follow the interest. The first month’s interest is $30,240 × 0.5833% = $176.40, so $422.39 goes to principal. Over 60 payments, interest totals $5,687.29 and the payments add up to $35,927.29.
How to read your result
The headline is the estimated monthly payment on the amount financed. The secondary figures show the amount financed, the sales tax computed from your rate, and total interest over the term. The donut splits the total of payments into the amount financed and interest, and the table and chart follow the balance month by month.
The amount financed is the figure to check against a dealer’s buyer’s order or a lender’s Truth in Lending disclosure. If they differ, the cause is usually a fee, add-on product, or tax treatment that was not entered. Sales tax here is charged on the price minus the trade-in, which many states allow but not all. Where tax applies to the full price, adding the extra tax (trade-in value × tax rate) to the fees field reproduces that.
The payment excludes insurance, registration renewals, fuel, and maintenance. A trade-in with a loan balance larger than its value is not netted automatically: enter a trade-in value of zero and add the negative equity to the fees field so it is financed.
What changes the result most
- Loan term
- Financing $30,240 at 7% costs $724.13 a month and $4,518.45 of interest over 48 months, $598.79 and $5,687.29 over 60, $515.56 and $6,880.46 over 72, and $456.40 and $8,097.82 over 84.
- Interest rate
- Over 60 months, 5% gives $570.67 a month and $3,999.97 of interest; 9% gives $627.73 and $7,423.96. Each 2 points moves the payment by about $28 to $29.
- Down payment and trade-in
- Each extra $1,000 down lowers the amount financed by $1,000 and the payment by $19.80; $10,000 down brings it to $499.78. Removing the $3,000 trade-in raises the amount financed by $3,210, not $3,000, because the trade-in also reduces the taxable amount, and the payment rises to $662.35.
Questions
Does this include sales tax?
Only the tax rate or amount you enter. The calculator does not determine local tax rules.
How does a trade-in affect the result?
The trade-in first reduces the taxable vehicle price. Any trade-in value above the price then offsets fees and the rest of the amount financed. Actual offers can include payoff balances and separate tax treatment.
Can I compare an auto loan with a lease?
Not with this calculator, and this site does not model leases. A lease payment depends on the vehicle's residual value, a money factor, mileage limits, and end-of-lease charges, while this tool amortizes a purchase loan to a zero balance. Compare a lease using the figures in the lessor's written disclosure.
How long should a car loan be?
Terms commonly run from 36 to 84 months. A longer term lowers the payment but adds interest: in this page’s example, going from 60 to 84 months cuts the payment by $142.39 and adds $2,410.53 of interest. Because cars lose value, a long term also raises the chance of owing more than the car is worth for part of the loan.
How much car can I afford?
This calculator works forward from a price. To work backward from a monthly payment, the loan affordability calculator converts a payment, rate, and term into a loan amount; adding the down payment and trade-in, and subtracting tax and fees, gives an approximate price. Rules of thumb about payment-to-income shares exist, but they are not standards, and insurance and running costs also belong in the budget.
What is a good APR for a car loan?
It depends on credit history, whether the car is new or used, the term, the lender, and market rates at the time, so no single figure applies. This site does not fetch live rates. Comparing written offers from several lenders on the same amount and term, and checking each APR on its disclosure, shows which is lower for a particular borrower.
More in Loans & debt
Sources
These references explain the concepts behind the calculation. They do not endorse this site. Estimates leave out any cost or condition you did not enter.