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Car Loan Calculator
Enter the vehicle price, down payment, trade-in, APR, term, and sales tax to see the monthly car payment, the amount financed, and the total cost of the loan.
Calculation inputs
Sales tax is applied to the price after the trade-in credit, as most US states do. Fees are not included.
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Complete the fields and select Calculate to show results here.
About this calculator
This calculator estimates the monthly payment on a car loan from the vehicle price, down payment, trade-in, sales tax, APR, and term. It also shows the amount financed, total interest, and the full cost, so you can compare loan offers before signing.
How the calculation works
- Sales tax = (price − trade-in) × tax rate
- Amount financed = price + sales tax − down payment − trade-in
- Payment = P × r ÷ (1 − (1 + r)^−n), where r = APR ÷ 12
Notes and assumptions
A longer term lowers the monthly payment but raises the total interest you pay.
A few states tax the full price regardless of trade-in; set the tax rate accordingly if yours does.
How it works in plain English
First the tool works out how much you are actually borrowing. Most US states charge sales tax on the price after the trade-in credit, so tax is the price minus the trade-in, times the tax rate. The amount financed is the price plus that tax, minus your down payment and trade-in value.
It then applies the standard amortized loan formula used by banks and credit unions. The APR is divided by 12 to get a monthly rate, and the payment is set so that the same amount each month pays off the balance and all interest by the end of the term. Early payments are mostly interest; later ones are mostly principal.
Total of payments is the monthly payment times the number of months, and total interest is that figure minus the amount financed. The total cost adds back your down payment and trade-in, giving the full amount the vehicle costs you. Dealer documentation, title, and registration fees vary by state and are not included.
The formula
- Sales tax = (price − trade-in) × tax rate
- Amount financed P = price + sales tax − down payment − trade-in
- Monthly payment = P × r ÷ (1 − (1 + r)^−n), r = APR ÷ 12, n = months
- Total interest = payment × n − P
Worked example
Suppose you are buying a $35,000 car with $5,000 down and a $3,000 trade-in, at 6.5% APR over 60 months, with 7% sales tax.
Sales tax is ($35,000 − $3,000) × 7% = $2,240, so the amount financed is $35,000 + $2,240 − $5,000 − $3,000 = $29,240.
With a monthly rate of 0.5417%, the payment comes to about $572.12. Over 60 months you pay about $34,327 in total, of which roughly $5,087 is interest. Stretching the same loan to 72 months drops the payment to about $491 but raises the interest to around $6,150.
Payment per $10,000 financed
| APR | 36 months | 48 months | 60 months | 72 months |
|---|---|---|---|---|
| 4% | $295 | $226 | $184 | $156 |
| 6% | $304 | $235 | $193 | $166 |
| 8% | $313 | $244 | $203 | $175 |
| 10% | $323 | $254 | $212 | $185 |
| 12% | $332 | $263 | $222 | $196 |
Source: calculated with the standard amortized loan formula; figures rounded to the nearest dollar.
Frequently asked questions
Is sales tax charged before or after the trade-in?
In most US states, sales tax applies to the price minus the trade-in value, which is how this tool calculates it. A few states tax the full price regardless. If yours does, you can approximate it by setting the trade-in to zero for the tax and lowering the price by the trade-in amount.
Should I choose a longer loan term?
A longer term lowers the monthly payment but increases the total interest, and you are more likely to owe more than the car is worth while it depreciates. Many buyers aim for 60 months or less; compare total interest across terms before deciding.
What is the difference between APR and interest rate?
APR is the yearly cost of borrowing including certain lender fees, expressed as a rate. For most auto loans it is very close to the note rate. Use the APR from your loan offer so the payment estimate reflects the true cost.
Does the result include fees and insurance?
No. Documentation fees, title, registration, extended warranties, and insurance vary by dealer and state. If you roll fees into the loan, add them to the vehicle price to see their effect on the payment.
How does a larger down payment help?
Every dollar down is a dollar you do not borrow, so it lowers both the monthly payment and the total interest. A larger down payment also reduces the chance of owing more than the car is worth early in the loan.