How This Calculator Works
Car-buying calculators usually let you enter a price and an interest rate and stop there. In practice, three other numbers change your real monthly payment just as much: what the dealer gives you for your trade-in, any manufacturer rebate applied to the deal, and how your state's sales tax treats both of those amounts. This calculator puts all of it together so the number you see is the number you'll actually be financing.
How Trade-In Value Affects Your Loan
Your trade-in value is subtracted directly from the vehicle price before financing, which lowers your loan amount and monthly payment. In most states, it also lowers the amount the dealer can charge sales tax on — sometimes called a "trade-in tax credit." A handful of states tax the full price of the new vehicle regardless of your trade-in, so the dropdown above lets you match your state's rule.
Manufacturer Rebates: Cash Back vs. Tax Treatment
A manufacturer rebate reduces what you owe, but in most states it does not reduce your taxable price — the dealer collects sales tax on the price before the rebate is applied, then the rebate is subtracted from the amount you finance. A smaller number of states tax the post-rebate price instead. Either way, the rebate still lowers your loan amount; the only question is whether it also lowers your tax bill.
Why "Out-the-Door Price" Matters
The out-the-door price is what you'd pay if you wrote one check today: vehicle price, minus trade-in and rebate, plus sales tax and fees. It's the number dealers sometimes avoid stating directly. Comparing out-the-door prices — not sticker prices — is the most reliable way to compare offers from different dealers.
Reading Your Results
The amount financed reflects your vehicle price minus trade-in, rebate, and down payment, plus sales tax and fees (tax and fees are typically rolled into the loan rather than paid in cash, though you can pay them separately if you prefer). The schedule below shows how each payment splits between principal and interest over the life of the loan.