Auto Loan Calculator

How an auto loan payment is calculated

Your monthly car payment depends on how much you actually finance — not the sticker price. This calculator starts from the vehicle price, adds sales tax, subtracts your down payment and any trade-in, and then spreads the result over your loan term using standard amortization to find the monthly payment, total interest, and total cost.

What goes into the amount financed

• Vehicle price — the agreed purchase price.
• Sales tax — applied here to the price after the trade-in is deducted, which is how most US states tax a car purchase (your trade-in lowers the taxable amount).
• Down payment & trade-in — both reduce what you borrow, lowering the payment and the interest you'll pay.

So: amount financed = price + sales tax − down payment − trade-in, then amortized over the term at your APR.

Tips to pay less

• Shorter terms cost less overall. A 72- or 84-month loan lowers the monthly payment but piles on interest and risks owing more than the car is worth.
• Shop the rate (APR). A pre-approval from your bank or credit union is a strong bargaining chip against dealer financing.
• A bigger down payment reduces interest and the chance of going "underwater."
• Mind the total cost, not just the monthly figure — dealers can shrink the payment by stretching the term.

FAQ

Does this include insurance, registration, or fees?

No — it covers price, tax, and financing only. Title, registration, documentation fees, and insurance are extra; some buyers roll certain fees into the loan, which would raise the amount financed.

Is sales tax calculated the same everywhere?

Not exactly. Most states tax the price minus trade-in (as here), but a few tax the full price. Use your local rate, and check whether your state gives the trade-in tax credit.

Is this calculator free to use?

Yes, it is completely free with no sign-up. Run as many loan scenarios as you like — try different terms, down payments, and rates to compare monthly payments and total interest side by side.

Does my data stay private?

Yes. Every calculation runs locally in your browser, so the vehicle price, your down payment, and any other figures you enter are never uploaded or stored on a server.

What APR should I enter if I don't have a quote yet?

Use a realistic estimate based on your credit and current market rates, then re-run it once you have a real pre-approval. Since the monthly payment is sensitive to APR, getting an actual rate quote before you buy will give you the most accurate figure.

Does a longer term really cost more if the payment is lower?

Yes. Stretching a loan to 72 or 84 months shrinks the monthly payment but increases the total interest you pay because you owe the balance for longer. Compare the "total cost" figure across terms, not just the monthly payment, to see the real trade-off.