Auto Loan Calculator
Estimate a monthly car payment, including a trade-in and sales tax.
How this works
This starts from the vehicle’s price, subtracts your trade-in and down payment, adds sales tax, then runs the result through the standard fixed-rate amortization formula (the same one behind a mortgage or any other installment loan, see the Loan Payment Calculator for the general version) to find a level monthly payment over your loan term.
Sales tax is calculated on the price after your trade-in is subtracted, since most US states let a trade-in reduce the taxable amount on a new purchase -- trading in a $15,000 car toward a $40,000 one usually means you’re only taxed on the $25,000 difference. A handful of states don’t work this way, or cap how much a trade-in can offset, so double-check your own state’s rule if the estimate looks off from what a dealer quotes you.
Frequently asked questions
Does a trade-in actually lower my sales tax?
In most US states, yes -- sales tax is calculated on the vehicle price minus your trade-in value, not the full price. A few states tax the full price regardless, and some cap how much a trade-in can offset, so it’s worth confirming your own state’s rule before assuming this estimate matches a dealer’s exact quote.
Does this include title, registration, or dealer fees?
No -- this covers vehicle price, trade-in, sales tax, and the loan itself only. Title, registration, documentation, and dealer fees vary by state and dealership and aren’t included, so your actual out-the-door price and payment may run a bit higher.
Is “interest rate” the same as APR here?
This calculator treats whatever rate you enter as the actual rate applied to the loan balance. A real auto loan’s advertised APR can bundle in certain fees on top of the base interest rate, which may make it a little higher than the plain interest rate a lender first quotes you.
Should I put more money down?
A larger down payment shrinks the amount you finance, which lowers both your monthly payment and the total interest paid over the loan. It also helps avoid being “underwater” (owing more than the car is worth) early in the loan, since a car’s value typically drops faster than a small loan balance does in the first year or two.