Auto Loan Calculator
Your real monthly car payment — with the down payment, trade-in credit, and sales tax handled the way dealers actually calculate them, plus the total interest over the loan.
Monthly payment
$642.55
Amount financed
$32,450.00
incl. $2,450.00 tax
Total interest
$6,102.93
Total cost
$43,552.93
incl. down & trade
Sales tax is applied to the price minus trade-in, which is how most US states calculate it (a handful tax the full price). Title, registration, and dealer fees aren't included — budget a few hundred dollars more at signing.
How Car Loans Are Structured
The amount you finance isn't the sticker price: sales tax is added (in most states on the price minus your trade-in), then the down payment and trade-in come off. That financed amount amortizes like any loan — and because cars depreciate fast, longer terms mean more months underwater, owing more than the car is worth.
Formula
Financed = price + tax − down payment − trade-in Payment = financed × r ÷ (1 − (1 + r)^−months), r = APR/12 Example: $35,000 car, $5,000 down, 7% tax, 7% APR, 60 mo: tax $2,450 → financed $32,450 → $642.55/mo Total interest ≈ $6,103
Frequently Asked Questions
What credit score gets a good car loan rate?
Lenders price by tier: roughly 781+ (super-prime) sees the best advertised rates, 661–780 (prime) lands near average, and below 600 the APR can run more than triple the prime rate. On a $30,000 loan over 60 months, the spread between tiers is easily $4,000–$8,000 in total interest.
Is a 72- or 84-month car loan a bad idea?
It buys a lower payment at real cost: more total interest, and years spent 'underwater' — owing more than the depreciating car is worth, which complicates selling, trading in, or replacing a totaled vehicle. A common guideline is to keep the term at or under 60 months and let the down payment, not the term, set the payment.
Do I pay sales tax on the full price if I have a trade-in?
In most states, no — tax applies to the price minus the trade-in credit, which is exactly how this calculator figures it. A handful of states (California among them) tax the full purchase price with no trade-in offset, so check your state's rule when the trade-in is large.
Should I get financing from the dealer or my own bank?
Get pre-approved by a bank or credit union first, then let the dealer try to beat it. Dealer financing can genuinely win — especially manufacturer promotional rates — but dealers can also mark up the rate a lender offers them. A pre-approval in hand converts the finance office from a negotiation into a comparison.