Vehicle Monthly Payment Calculator

What goes into a vehicle payment

A car payment is not the sticker price divided by the number of months. Five inputs decide it: the price, the trade-in allowance, the cash you put down, the tax and fees your state adds, and the loan terms. Change one and the payment moves.

The first group sets how much you borrow. The finance office calls it the amount financed: price minus trade-in and cash down, plus sales tax, the dealer doc fee and title or registration charges. The second group sets how you repay it: the annual percentage rate and the number of months.

The payment comes from an amortizing formula, not simple division. Early payments are mostly interest, so the balance falls slowly at first. That is why $32,194 at 7.9 percent over 60 months costs $651.24 a month, while dividing the same balance by 60 gives $536.57 and leaves the interest unpaid.

The amount financed, line by line

Start with the agreed price. Subtract the trade-in allowance, which is what the dealer credits for your old car, and subtract the cash you hand over. Add sales tax on the taxable amount, the doc fee the dealer charges for paperwork, and the title and registration fees the state collects.

Sales tax is the line people get wrong. Most states tax the price after the trade-in, so a $5,000 trade saves 5,000 x 0.065 = $325 in tax as well as $5,000 of loan. A handful of states tax the full price, and the tax basis toggle in the calculator handles that case.

A worked example on a $38,000 vehicle

Take a $38,000 vehicle with a $5,000 trade-in, $4,000 cash down, 6.5 percent sales tax, a $599 doc fee, $450 for title and registration, a 7.9 percent APR and a 60 month term.

The taxable amount is 38,000 - 5,000 = $33,000, so tax is 33,000 x 0.065 = $2,145. Amount financed is 38,000 - 5,000 - 4,000 + 2,145 + 599 + 450 = $32,194.

For the payment, the monthly rate is 0.079 / 12 = 0.0065833 and n is 60. Run P x r / (1 - (1 + r) to the negative n) and you get $651.24. Total of payments is 651.24 x 60 = $39,074.31, and interest is 39,074.31 - 32,194 = $6,880.31.

Now count what leaves your hands. The $4,000 down plus $39,074.31 in payments plus $5,000 of trade equity is $48,074.31 for a vehicle priced at $38,000. The gap is tax, fees and interest: 2,145 + 1,049 + 6,880.31 = $10,074.31.

The first payment splits into $211.94 of interest and $439.30 of principal, because interest is charged on the full $32,194. By the final year that split reverses and most of each payment retires the balance. That is the reason paying an extra $50 a month early in the loan saves more than the same $50 paid in year four.

How the term changes the payment

Term trades payment size for total interest, and the trade is not even. The same $32,194 balance at 7.9 percent produces five different deals.

The 84 month loan cuts the payment by 651.24 - 500.18 = $151.06 against the 60 month loan and adds 9,821.13 - 6,880.31 = $2,940.82 of interest. It also keeps you upside down longer, because the balance falls more slowly than the car loses value.

Every extra year of term adds roughly $1,400 to $1,500 of interest on a loan this size, and the monthly saving shrinks with each step: the first year of extra term frees up $223, the last one only $63. Take the shortest term the budget can carry without touching an emergency fund.

Why the trade-in matters twice

The trade-in does two jobs. It cuts the amount financed by its appraised value, and in most states it cuts the sales tax base as well. The second effect is smaller but real: $5,000 of trade saves $325 in tax at 6.5 percent.

Losing the tax credit alone costs $6.57 a month and $69.46 of interest. Losing the trade-in entirely costs $107.72 a month, because you are financing the $5,000 of equity you gave up along with the tax on it.

Get a written offer from a car buying service before you accept the dealer's number. The trade-in figure is negotiable; the sales tax credit is not.

APR, add-ons and negative equity

The APR is the rate that includes finance charges, so it is the number to compare across lenders. A 6.49 percent note rate with a $500 origination fee is not cheaper than a 6.75 percent loan with no fee once the fee is financed.

Dealer add-ons land in the amount financed, not in a separate bill. Gap coverage, a service contract, tire and wheel protection and paint sealant each add to the balance and each collects interest for the whole term. $2,000 of add-ons on this loan adds about $40 a month and $427 of interest over 60 months.

Negative equity works the same way. Trading a car you owe more on than it is worth rolls the difference into the new loan. On this deal, $3,000 of negative equity raises the payment by $55.42 and adds $585.58 of interest at 7.9 percent over 60 months.

A credit union or bank preapproval gives you a rate to compare before you sit at the dealer's desk. The Federal Reserve publishes average rates on car loans at commercial banks in its G.19 consumer credit release, which is a reasonable benchmark for a good credit score. The Consumer Financial Protection Bureau auto loan guide explains how dealer financing, add-ons and trade-ins fit together, and its car loan explainer covers the paperwork you should receive before signing.

Sales tax and fee rules that move the number

Sales tax on a vehicle is set by the state, and the rate depends on where you register the car, not where you buy it. County and city add-ons can push a 4 percent state rate to 8 or 9 percent at the counter. On a $33,000 taxable amount that spread is $1,320 to $2,970.

Trade-in credit is the other variable. Most states tax only the difference, a few tax the full price, and a few give a partial credit. The toggle in this calculator covers both cases, and the state revenue department page for your address settles which one applies.

Doc fees are capped in some states and unregulated in others. Where they are capped, the cap is often low enough that the fee cannot be padded. Where they are not, $599 is common and $999 shows up at some dealers. Ask for the out the door price in writing, with tax and every fee listed, before you discuss the monthly payment.

Buying across state lines adds a wrinkle. Tax is usually paid where you register the car, not where you buy it, so a deal in a low tax state does not save the tax once you title the car at home. Some dealers collect the home state tax and some leave it to you at the DMV counter, which changes the cash you need on pickup day.

Title, registration and plate fees usually run $50 to $500. A few states also charge an annual personal property tax or excise tax on vehicles, which is separate from the sales tax and does not appear on the purchase contract.

What this calculator leaves out

The payment is one line in the cost of owning a car. Insurance on a new $38,000 vehicle often runs $150 to $250 a month for a driver with a clean record, fuel runs $100 to $200 depending on miles, and maintenance and tires add $50 to $100. Budget the payment plus those lines before you sign.

The monthly payment is also the wrong number to negotiate on. Dealers can stretch the term or trim the down payment to hit a payment target while the out the door price and the interest bill grow. Settle the price first, then the trade-in, then the financing.

Depreciation is the largest cost and the one no calculator shows. A new vehicle commonly loses 20 percent of its value in the first year, which is $7,600 on this purchase, and about half over five years.

Three more items sit outside the model. Manufacturer rebates are taxed in most states and are not subtracted here, so a $2,000 rebate reduces the amount financed by $2,000 but not the tax. Late payments trigger fees and can raise the APR on a subprime contract. And refinancing later resets the term, which can lower the payment while adding interest.

Use the payment number to test the budget, then use the out the door price to negotiate. A dealer who will not quote the out the door figure in writing is telling you something.