Car Loan Calculator
Pick your state to load its live sales tax rate, then enter the price, down payment, trade-in, and term. We finance the tax at the live FRED auto-loan APR to show your true out-the-door payment.
The sticker price is just the start. Sales tax adds ~$1,994 to a $28,000 car and, once financed, quietly earns the lender another ~$403 in interest. Know the out-the-door number before you sign.
$1,994
Sales tax on a $28,000 car at the 7.12% US-average rate — financed into the loan and quietly earning ~$403 of interest
7.5%
Live FRED 48-month new-car APR used as the default rate
42
States that grant a trade-in sales-tax credit, cutting the taxable price by your trade-in value
What dealers don't volunteer about your car loan
Monthly payment is only one number. Here are the three that actually matter.
Sales tax is the line most calculators skip
Your state's combined rate is applied to the price and rolled into the loan. On the $28,000 default at the 7.12% US average, that's $1,994 added to the out-the-door price — and because it's financed, it accrues about $403 of extra interest over 5 years. This tool pulls each state's live rate so the payment you see is the real one.
Your trade-in can cut the tax, not just the loan
In ~42 states a trade-in reduces the taxable price. An $8,000 trade-in on a $28,000 car in Texas is taxed on just $20,000 ($1,640) — but in California, which gives no trade-in credit, you'd pay on the full $28,000 ($2,430). The calculator applies your state's rule automatically, so the credit can be worth $790+ before it even touches the loan.
Longer terms cost more — always
On the $26,994 default loan at 7.5% APR, going from 48 to 72 months drops the payment from $652.69 to $466.73 — but interest climbs from $4,335 to $6,611. That's $2,275 more for the same car, plus more years underwater. Pick the shortest term your budget can absorb.
How the Car Loan Calculator Works
Formula
Taxable Price = Vehicle Price − Trade-In (− Trade-In only in trade-in-credit states)
Sales Tax = Taxable Price × State Combined Rate
Out-the-Door = Vehicle Price + Sales Tax
Loan Amount = Out-the-Door − Down Payment − Trade-In
r = APR / 100 / 12 (monthly rate)
n = Loan Term (months)
Monthly Payment = Loan × [r × (1+r)^n] / [(1+r)^n − 1]
Total Interest = (Monthly Payment × n) − Loan Amount
Total Cash Cost = (Monthly Payment × n) + Down Payment
Worked example — $28,000 car, US-average 7.12% tax, $3,000 down, 7.5% APR, 60 mo:
Sales Tax = $1,994 · Out-the-Door = $29,994 · Loan = $26,994
Monthly = $540.90 · Interest = $5,460 · Total Cash Cost = $35,454Pick your state
Loads the live combined sales tax rate (Tax Foundation 2026) and whether your state grants a trade-in tax credit.
Enter price, down payment, and trade-in
In most states the trade-in lowers both the taxable price and the loan; the down payment lowers only the loan.
Set the APR and term
The APR defaults to the live FRED 48-month new-car average (used cars run ~3 points higher).
Read the out-the-door numbers
Monthly payment, financed sales tax, amount financed, total interest, and total cash cost over the life of the loan.
Most car payment calculators quote the sticker price and ignore sales tax — so the payment you plan around is lower than the one you sign for. This tool builds the out-the-door price first: it applies your state's live combined rate (and the trade-in credit where your state allows it), then finances that tax along with the car. On the $28,000 default, the 7.12% US-average rate adds $1,994 and accrues roughly $403 of interest over five years.
Two live data layers keep it honest: state sales tax from the Tax Foundation and the new-car APR from the St. Louis Fed (FRED), refreshed automatically. Getting pre-approved at a bank or credit union before you shop separates the price negotiation from the financing negotiation and gives you a real rate benchmark to beat.
Frequently Asked Questions
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