Auto Loan Calculator
Calculate your monthly car payment with sales tax, trade-in credit, and down payment. See total interest paid, the amount financed, and the impact of different loan terms.
How to Use
- Enter the vehicle's purchase price (the negotiated price before tax).
- Enter your cash down payment.
- Enter the trade-in value if you're trading in your current vehicle. In most U.S. states this reduces your taxable amount.
- Enter the loan APR you've been quoted by your bank, credit union, or dealer.
- Pick the loan term — 36 to 84 months. Shorter terms have higher payments but much lower total interest.
- Enter your local sales tax rate. The calculator applies it to (price − trade-in).
- Read the monthly payment, total amount financed, total interest, and total cost over the life of the loan.
Formulas
A Brief History of Auto Financing
Auto financing started essentially with the automobile itself. General Motors created GMAC (now Ally Financial) in 1919 to lend money to dealers and customers, recognizing that selling a $1,000 Buick — roughly two years' wages for a working family — required something more than cash on the barrelhead. Ford, philosophically opposed to debt under Henry Ford himself, lagged behind and lost market share until the Ford Motor Credit Company arrived in 1959. By the mid-20th century, captive auto lenders were common, and dealers became as much finance offices as showrooms.
Term lengths have crept upward steadily. In 1970 a typical auto loan was 36 months. By 1990, 48 months was the norm. Today the average new-car loan is just under 70 months, with 84-month and even 96-month loans available — a direct consequence of vehicle prices rising faster than household incomes. Longer terms keep monthly payments affordable but extend the period of negative equity (owing more than the car is worth) and increase the chance of rolling old loan balances into new car purchases.
The 2008 financial crisis exposed how aggressive auto subprime lending had become; the post-crisis subprime auto market quickly rebuilt and reached new highs. Today's auto lender, dealer F&I office, and the calculator above all use the same underlying math — the standard amortizing loan formula — but how that math gets used has shifted considerably toward the longer-term, higher-balance lending that defines modern car-buying.
About This Calculator
This calculator handles the common U.S. auto-financing structure: vehicle price minus trade-in is the taxable amount; tax is added to the financed total; down payment and trade-in equity reduce what you actually borrow; the result amortizes monthly over your chosen term. It assumes the trade-in tax credit, which applies in most states; if you're in Virginia, California, Maryland, the District of Columbia, or one of the few other no-credit states, set trade-in to zero in this tool and apply tax to the full price.
What it doesn't include: dealer fees (doc fees, prep, title, registration), GAP insurance, extended warranties, or other F&I add-ons. Those typically add $500–$2,500 to the financed amount and are worth scrutinizing line by line. Everything runs entirely in your browser; no income, credit, or VIN information is transmitted or stored. Use this for shopping; verify with the lender's official Truth-in-Lending disclosure before signing.
Frequently Asked Questions
Is dealer financing better than getting a loan from my bank?
Sometimes — manufacturer captive lenders (e.g., Toyota Financial, GM Financial) often offer promotional rates as low as 0% on new cars to move inventory. Otherwise, banks and credit unions usually beat dealer markups. Always get pre-approved before walking into the dealership and use that as your benchmark.
Should I take a longer term to lower the payment?
Lower payment, much higher total interest, and a higher risk of being upside down (owing more than the car is worth). 84-month loans on $40k cars are extremely common now and a big driver of negative equity. If you can't afford the 60-month payment, you generally can't afford the car.
What's the trade-in tax credit?
Most U.S. states (about 41 of them, with Virginia, California, Maryland, and a few others as exceptions) tax only the difference between the new car's price and the trade-in value, not the full new-car price. Trading in a $10,000 car at a 7% sales tax rate saves you $700 in tax.
How much should I put down?
20% down is the traditional rule but rare in practice. The real reason for a down payment is to avoid being upside down — new cars depreciate roughly 20% in the first year, so 20% down keeps you above water. If you finance the entire purchase, expect negative equity for the first 2–3 years on most vehicles.
Why is the dealer pushing GAP insurance and extended warranties?
These have very high markups — they're profit centers for the F&I (finance and insurance) office, not deals for the buyer. GAP insurance can be useful if you put little or nothing down, but you can usually get it cheaper from your auto insurer. Extended warranties are nearly always priced above their actuarial value.
Should I pay cash or finance and invest the difference?
Pure math: if your loan rate is below your expected after-tax investment return, financing wins. At sub-3% promotional rates that math is easy. At today's 7%+ rates the case is much weaker, especially after considering investment volatility. The non-financial argument: paying cash removes a recurring obligation, which is worth something in itself.
Common Use Cases
Negotiating with the dealer
Know your monthly payment for the price they're quoting before you walk in. Keeps the conversation focused on price, not on monthly payment manipulation.
Comparing 60-month vs. 72-month
See how much extra interest the longer term costs in absolute dollars, then weigh against the lower monthly payment.
Choosing between two cars
Run both vehicles through the calculator to see the actual lifetime cost difference, not just the sticker-price difference.
Trade-in vs. private sale decision
Compare the after-tax value of trading in (with the sales tax credit) against selling privately for more money.
Pre-approval shopping
Plug in different rates from your bank, credit union, and dealer pre-approval to find the best financing offer.
Budgeting for a future car
Work backwards from a comfortable monthly payment to find the maximum vehicle price you should consider.
Last updated: