This auto loan calculator builds your amount financed from the whole deal — vehicle price, minus trade-in, plus sales tax and dealer fees, minus your down payment — then amortizes it into a fixed monthly car payment, the total interest and the total repayment. Sales tax is applied to the price after the trade-in credit, the way most US states tax a car purchase, and tax and fees are rolled into the loan just as a dealer would structure it. Prefer to type the loan amount directly? Switch to Amount financed mode. Enter the term in months or years — 60 and 72 months are the common auto terms.
How to Work Out Your Car Payment
Build the deal, add the rate, read the payment.
1
Enter the deal
Type the vehicle price, your cash down payment and any trade-in value. Trade-in lowers both the amount financed and the tax.
2
Add tax and fees
Set your state sales-tax rate and put title, registration and dealer fees in the Fees box. Both are rolled into the loan.
3
Set rate and term
Enter the APR from your pre-approval or quote and the term in months. See the monthly payment, total interest and total repaid.
What Goes Into the Amount Financed
The loan is the whole deal minus what you put down.
Every car deal reduces to one number the lender charges interest on — the amount financed. This calculator assembles it in the same order a dealer's finance office does:
Vehicle price — the agreed sale price of the car.
− Trade-in value — what the dealer credits you for your old vehicle, subtracted before tax.
+ Sales tax — your state rate applied to the price after the trade-in credit.
+ Title, registration and dealer fees — the extra line items, rolled into the loan.
− Down payment — the cash you pay up front, which comes straight off the top.
What is left is the amount financed. Raise the down payment or the trade-in and it shrinks — along with the monthly payment and the total interest.
How Your Credit Score Moves the Rate
Illustrative tiers — enter your own quoted APR for an exact payment.
Auto-loan APRs are tiered by credit score: the stronger your credit, the lower the rate, and the gap between the top and bottom tiers is large enough to swing the monthly payment by a lot. The bands below are illustrative of how lenders group borrowers — actual rates depend on the lender, the term, whether the car is new or used, your down payment and current market conditions, so use the APR on your own pre-approval or dealer quote in the calculator above.
Credit tierScore rangeRelative APR
Excellent750+Lowest advertised rates
Good700–749Slightly above the best rates
Fair640–699Noticeably higher
SubprimeBelow 640Highest — often double-digit APR
Because the rate compounds over the whole term, moving up even one tier can save hundreds or thousands in interest on the same car. If your score is borderline, it is often worth improving it before financing, or shopping a credit union and a bank pre-approval against the dealer's offer.
Frequently Asked Questions
How is my monthly car payment calculated?
The calculator first works out the amount financed — the sum you actually borrow — then runs the standard amortization formula on it: M = P × r(1+r)ⁿ ÷ ((1+r)ⁿ − 1), where P is the amount financed, r is the annual rate divided by 12, and n is the number of monthly payments. The amount financed is the vehicle price, minus your trade-in, plus sales tax on that reduced amount, plus title, registration and dealer fees, minus your cash down payment. Whatever is left over is what the lender loans you and charges interest on. The result is the single fixed monthly payment that clears the balance over the term, plus the total interest and total repayment. Everything runs in your browser, so nothing you type is sent anywhere.
How does a trade-in reduce the sales tax on a car?
In most US states you only pay sales tax on the price after your trade-in is deducted, not on the full sticker price — so a trade-in cuts both the amount financed and the tax bill. If you buy a $32,000 car and trade in a vehicle worth $8,000, most states tax you on $24,000, which at a 7% rate is $1,680 of tax instead of $2,240 — a $560 saving purely from how the tax is applied. This calculator follows that common rule: it applies the sales-tax rate to the price minus the trade-in. A handful of states tax the full purchase price with no trade-in credit; if you live in one of those, add the extra tax into the Fees field so the amount financed stays accurate.
Should I choose a 60, 72, or 84-month auto loan?
A longer term lowers the monthly payment but raises the total interest and keeps you at risk of owing more than the car is worth. Stretching the same loan from 60 to 72 or 84 months shrinks each payment, which is why dealers offer long terms — but you pay interest for more years, so the total cost climbs, and because cars depreciate faster than a long loan pays down, you can spend most of the term "upside down" (owing more than the car's value). Enter the same price and rate at 48, 60 and 72 months and watch the monthly payment fall while the total interest rises. A common guideline is to keep an auto loan at 60 months or less; if only a longer term makes the payment fit, that is usually a sign the car is more than the budget can comfortably carry.
Does this include tax, title, registration and dealer fees?
Yes — sales tax, title, registration and dealer fees can all be rolled into the amount financed, which is exactly how most dealers structure the deal. Enter the sales-tax rate for your state and put title, registration, documentation and any dealer add-on fees into the Fees field. The calculator adds tax (on the price after trade-in) and fees to the amount financed, so they are borrowed and accrue interest just like the car itself, and the "Amount financed" line breaks the total down so you can see each piece. If you plan to pay tax and fees in cash up front instead of financing them, leave the Fees field at zero and add that cash to your down payment.
Why is the interest rate on a used car higher than on a new one?
Used-car loans almost always carry a higher APR than new-car loans, because a used vehicle is worth less collateral to the lender and its value is harder to predict, so the loan is riskier. New cars also frequently qualify for manufacturer-subsidized promotional financing — the 0% and low-rate offers you see advertised — which is rarely available on used inventory. On top of the new-versus-used gap, your own credit score, the loan term and the size of your down payment all move the rate. This calculator takes whatever annual rate you enter, so grab the exact APR from your pre-approval or the dealer's quote rather than an advertised teaser rate to get a payment that matches reality.
What is negative equity, or being "upside down" on a car loan?
Negative equity means you owe more on the loan than the car is currently worth, and it is common early in a long loan with little money down. A new car can lose a large share of its value in the first couple of years, while a long loan with a small down payment pays the balance down slowly — so for a stretch, the payoff amount is higher than the resale value. That becomes a real problem if the car is totalled or you want to sell, because you would have to cover the gap out of pocket, which is what gap insurance is designed to protect against. A larger down payment and a shorter term are the two levers that keep you from going upside down; try raising the down payment in the calculator and watch the amount financed — and your exposure — shrink.
How big should my down payment be on a car?
A frequently cited rule of thumb is 20% down on a new car and 10% on a used one, though any amount you can put down helps. A bigger down payment cuts the amount financed, which lowers the monthly payment and the total interest, and it front-loads your equity so you are far less likely to end up owing more than the car is worth. It can also help you qualify for a better rate. Enter different down-payment figures in the calculator and compare the amount financed, the monthly payment and the total interest — you will see how quickly a larger deposit pays for itself in interest saved. Trade-in value counts toward your effective down payment too, since it reduces the amount financed the same way cash does.