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Auto Loan Calculator
Sticker price, sales tax, trade-in, rebates — they all land in your monthly car payment. This auto loan calculator turns them into the real number, with total interest, cash due at signing and a full amortization schedule.
See how this works on a $35,000 car — 3 real examples
Monthly payment
$0
Loan amount
$0
Sales tax
$0
Total interest
$0
Upfront cash
$0
What makes up the amount financed
One payment, month by month
- Interest—
- Principal—
Loan balance over time
Amortization scheduleMonth-by-month breakdown
How your auto loan payment is calculated
Sales tax is charged on the price after the trade-in (the treatment in most states), then the loan rolls tax and fees in and takes your down payment, trade-in and rebate out:
taxable = max(0, price − trade-in)
sales tax = taxable × tax%
loan = price + tax + fees − rebate − down − trade-in + owed
M = loan · r(1 + r)n / ((1 + r)n − 1)
r = APR / 12 n = term in months
where M is the monthly payment. Total interest is the sum of the monthly payments minus the amount financed, and total cost is price + interest + sales tax + fees. By default the sales tax and fees are financed (rolled into the loan), so the only cash due at signing is your down payment — that is the "upfront cash" figure. Any balance still owed on the trade-in is added back as negative equity. Assumptions: the APR is fixed for the whole term, the first payment lands one month from today, and the sales-tax rate is exactly what you enter — we keep no 50-state tax tables, so the number is only as accurate as your rate. At 0% APR the payment is simply the loan divided by the number of months.
One car, three payoff dates
Same $35,000 car, same 7% loan on $34,450 with tax and fees folded in. Only the term changes — and it quietly reprices the car.
Paid off fast: 36 months
per month$1,063.72
- The steepest payment of the three, and the only one that clears the debt before year four.
- Interest comes to $3,844 — the least this car can cost to finance.
- Tax and fees ride along in every version here: $2,450 and $500 folded into the $34,450 borrowed.
The car costs $41,794 all in; both longer schedules start from there and add.
Load this example (opens in a new tab)The dealership default: 60 months
per month$682.15
- Stretching to five years takes $381.57 off each month's payment.
- The interest bill grows to $6,479 — $2,635 more than the three-year loan pays.
- All in, the same car now runs $44,429.
$381.57 of monthly breathing room, bought with $2,635 in extra interest.
Load this example (opens in a new tab)Seven years of car payments
per month$519.94
- The payment falls to less than half of the three-year figure.
- Interest climbs to $9,225 — more than double the $3,844 the fast loan pays.
- A $35,000 car ends up costing $47,175, which is $5,381 beyond the 36-month total.
Half the payment, seven years of it, and $5,381 added to the price of the same car.
Load this example (opens in a new tab)Illustrations only, not financial advice. Your own rate, taxes and insurance will differ — check with a qualified financial advisor before acting on any of this.
Auto loans, in plain English
- The sticker price is not the loan. Sales tax and fees push the financed amount up; your down payment, trade-in and rebates pull it down. This tool shows exactly what you end up borrowing.
- A trade-in cuts your tax too. In most states you are taxed only on the price after the trade-in, so a trade lowers both the loan and the sales tax.
- Longer terms hide a bigger bill. Stretching to 84 months shrinks the monthly payment but piles on interest and keeps you underwater far longer.
- Watch for negative equity. Owing more than your trade is worth rolls the gap into the new loan, so you start the next car already behind.
- Bring your own rate. Get pre-approved by a bank or credit union before you shop — it gives you a rate to beat and a check on dealer financing.
Related calculators
Frequently asked questions
How does this auto loan calculator figure my monthly payment?
The financed amount is the vehicle price plus sales tax and fees, minus your down payment, trade-in and any rebates, plus any balance still owed on the trade-in. That loan is then amortized with the standard payment formula: M = P × r(1+r)ⁿ ÷ ((1+r)ⁿ − 1), where P is the loan amount, r the monthly rate and n the number of months. On a $35,000 car with 7% sales tax, a $500 fee and $3,500 down at 7% APR for 60 months, that works out to about $665 a month.
How does a trade-in affect my loan amount and my sales tax?
A trade-in does double duty. Its value is subtracted from the price you finance, and in most states the sales tax is charged only on the price after the trade-in — so trading in a $10,000 car on a $35,000 purchase in an 8% state saves you $800 in tax on top of the $10,000 off the loan. This calculator uses that price-minus-trade-in tax base. If you still owe money on the trade-in, that balance gets rolled into the new loan as negative equity.
Should I include taxes and fees in the loan or pay them upfront?
By default this calculator finances the sales tax and fees, so the only cash due at signing is your down payment. Rolling tax and fees into the loan keeps your out-of-pocket cost low but means you pay interest on them for the whole term. Paying them upfront raises your cash at signing but shrinks the loan and the interest. Either way the vehicle costs the same before financing — the difference is how much interest you add.
How much of a down payment do I need for a car?
There is no legal minimum, but a common guideline is 10–20% down on a new car and at least 10% on a used one. A bigger down payment lowers the loan, the monthly payment and the total interest, and it helps you avoid being "underwater" — owing more than the car is worth as it depreciates. Even a few thousand dollars down noticeably cuts the payment; try adjusting the down-payment field to see the effect instantly.
What is negative equity and how does it get rolled into a loan?
Negative equity means you owe more on your trade-in than it is worth. If your old car is valued at $8,000 but you still owe $11,000, the $3,000 gap is added to your new loan on top of the new car. That means you finance more than the car costs, so you start the new loan already underwater. This calculator adds the amount owed to the financed total and flags when a trade-in has negative equity.
Are manufacturer rebates and cash incentives taxed?
It depends on the state. Some states calculate sales tax on the full price before the rebate, others on the price after it. This calculator treats a cash incentive as a straight reduction of the amount financed and applies sales tax to the price (net of trade-in), which matches the "rebate does not reduce the tax base" convention. If your state taxes the post-rebate price, lower the sales-tax rate slightly to approximate it — we keep no 50-state tax tables.
What is the difference between dealership financing and direct lending?
With dealership (indirect) financing the dealer arranges the loan through its lending partners, often marking up the rate. With direct lending you get pre-approved by a bank or credit union first and bring that offer to the dealer. Getting a direct-lending quote before you shop gives you a rate to beat and real negotiating leverage. Enter whatever APR you have been quoted here to see exactly what it costs over the life of the loan.
Disclaimer: these calculators are educational tools, not financial advice. They model your inputs with published formulas, but they cannot know your full situation — for decisions with real stakes, talk to a qualified professional. Formulas and defaults last reviewed .