Auto Loan Calculator

What this estimate assumes

• Sales tax is estimated on the vehicle price minus your trade-in value, which is how many (not all) states calculate it — check your state's rule.
• The monthly payment uses the standard fixed-rate amortization formula and doesn't include title/registration fees, dealer add-ons, or extended warranties.

How to use this calculator

1. Enter the agreed purchase price of the vehicle in Vehicle price ($) — use the out-the-door negotiated price, not the sticker/MSRP.
2. Enter how much cash you're putting down in Down payment ($).
3. If you're trading in a vehicle, enter its value in Trade-in value ($) — this reduces both what you finance and, in most states, what you're taxed on.
4. Enter your state's sales tax rate in Sales tax rate (%), if you want tax rolled into the loan amount.
5. Enter the rate you've been quoted in Interest rate (APR %), and your loan length in Loan term (months) — commonly 36, 48, 60, or 72.
6. Click Calculate monthly payment to see your monthly payment and total interest over the life of the loan.

Worked example

Using the calculator's own default numbers: a $32,000 vehicle, $3,000 down, no trade-in, 6.5% sales tax, 7.5% APR, over 60 months.

Sales tax applies to the price minus any trade-in — here that's the full $32,000 — so tax comes to $32,000 × 6.5% = $2,080. Add that to the price and subtract your down payment and trade-in: $32,000 − $3,000 − $0 + $2,080 = $31,080 financed. At 7.5% APR over 60 months, the monthly rate is 0.625%, and the standard amortization formula on $31,080 works out to a payment of about $622.77/month. Multiply that by 60 months and subtract the $31,080 principal, and total interest paid over the life of the loan comes to roughly $6,286.

Frequently asked questions

Why is my financed amount higher than the vehicle price minus my down payment?

Because sales tax gets added back in. The calculator first figures your tax bill on the taxable amount (price minus trade-in), then adds that tax to what you're financing after your down payment and trade-in are subtracted — so the loan amount can land above the price-minus-down-payment figure if the tax outweighs your down payment and trade-in combined.

Does trade-in value reduce my sales tax even though it doesn't show as a separate deduction?

Yes — the calculator subtracts your trade-in from the vehicle price before applying the tax rate, which matches how most (not all) states calculate trade-in tax credit. A few states tax the full purchase price regardless of trade-in, so check your state's specific rule if the number looks off.

What if I don't know my exact sales tax rate?

Leave it at your best estimate or look up your state and county combined rate online — sales tax on vehicles ranges from 0% in a handful of states to over 8% in others, and it meaningfully changes both your financed amount and monthly payment.

Does this include registration fees, dealer fees, or an extended warranty?

No. This covers price, trade-in, sales tax, down payment, rate, and term only. Title/registration fees, documentation fees, and any add-ons like extended warranties or GAP insurance are separate costs dealers often roll into financing — ask for an itemized breakdown before signing so you know exactly what you're financing.

How much does loan term length actually change what I pay?

A shorter term (like 36 or 48 months) means a higher monthly payment but much less total interest, since you're paying down the balance faster. A longer term (72 or 84 months) lowers the monthly payment but can more than double the interest paid, and increases the risk of owing more than the car is worth. Try 36 vs. 72 months on the same price and rate to see the gap for yourself.

Why did my payment change a lot when I added a trade-in?

A trade-in reduces both the amount you finance and, in most states, the taxable amount — so it has a double effect on lowering your monthly payment compared to an equivalent cash down payment, which only reduces the financed amount.