Auto Loan Calculator
By Baolin Gong, AFP · Founder, USFinCalc · Reviewed against primary sources (IRS, SSA, state revenue authorities).
Your monthly car payment is set by the amount financed, the interest rate, and the loan term. The amount financed is the vehicle price plus sales tax, minus your down payment and any trade-in credit. A longer term lowers the monthly payment but raises the total interest you pay over the life of the loan. This calculator shows both your payment and that total interest.
See your true monthly car payment — including sales tax, trade-in credit, and down payment, plus the total interest you'll pay.
What the car really costs
The total you pay over the life of the loan, split into the vehicle price, sales tax, and loan interest. The interest slice grows with a longer term or higher APR.
How this auto loan calculator works
The sticker price is only part of what you actually finance. This calculator shows your true monthly car payment by accounting for the things dealerships often gloss over: sales tax, your trade-in credit, and your down payment. The result is a realistic payment and — just as important — the total interest you'll pay over the life of the loan.
Here's the math. In most states, sales tax is charged on the vehicle price minus your trade-in value, so trading in a car lowers your tax bill. The amount you finance is the vehicle price plus that sales tax, minus your down payment and trade-in. That balance is then amortized over your loan term at your APR to produce a fixed monthly payment.
Key terms explained
Amount financed. The loan balance after your down payment and trade-in are applied and sales tax is added. This is what interest is charged on.
APR. The annual percentage rate — the yearly cost of borrowing. Even a one-point difference in APR can mean hundreds or thousands of dollars over a multi-year loan.
Trade-in credit. The value the dealer gives you for your current vehicle. Beyond lowering the loan, in most states it also reduces the taxable amount — a real and often-overlooked saving.
Loan term. How long you take to repay, in months. Longer terms shrink the monthly payment but raise total interest, and they keep you "underwater" (owing more than the car is worth) longer.
2026 car-buying reference
Auto loan APRs vary widely by credit score and whether the car is new or used. Through 2026, well-qualified buyers have generally seen new-car APRs in the mid-single digits, with used-car rates running higher. Stretching to an 84-month loan to hit a lower monthly payment is increasingly common, but it sharply increases total interest — switch the term in the calculator to see the difference on your numbers.
Before you sign, make sure the payment fits your budget. Run your real take-home pay first, and keep total transportation costs at a sustainable share of your income. Sales tax treatment of trade-ins varies by state, so confirm your local rules with the dealer or your state DMV.
Worked example: the real cost of stretching the term
Take the calculator's default scenario: a $35,000 vehicle with $5,000 down and a $3,000 trade-in, in a state that charges 7% sales tax on the price minus trade-in. Sales tax comes to $2,240, so the amount financed is $29,240. Here is that same loan at 6% APR across five common terms:
| Term | Monthly payment | Total interest | Total vehicle cost |
|---|---|---|---|
| 36 months | $890 | $2,783 | $40,023 |
| 48 months | $687 | $3,722 | $40,962 |
| 60 months | $565 | $4,677 | $41,917 |
| 72 months | $485 | $5,651 | $42,891 |
| 84 months | $427 | $6,641 | $43,881 |
Going from 36 to 84 months cuts the payment by $463 but costs $3,858 more in interest — and for most of an 84-month loan you owe more than the depreciating car is worth, which matters if it's totaled or you need to sell. Dealers quote the monthly payment because it's the number that feels affordable; the total-cost column is the number that actually leaves your pocket.
APR is the other multiplier. On the same 60-month loan, moving from 6% to 9% — roughly the gap between a strong credit score and a fair one — raises the payment from $565 to $607 and adds about $2,500 of interest. Checking your rate with a bank or credit union before visiting the dealership gives you a benchmark the finance office has to beat, and it costs nothing.
Notice also what the trade-in did in this example: beyond reducing the loan by $3,000, it cut the taxable amount, saving $210 in sales tax at 7%. In the handful of states that tax the full price regardless of trade-in (California among them), that second benefit disappears — one more reason to run your own state's numbers above.
Beyond the loan: the costs this calculator can't see
The loan payment is the largest but not the only recurring cost of ownership. Insurance on a newer vehicle commonly runs $100–$250 a month depending on your state, age, and record; registration and property taxes on vehicles apply in some states; and fuel plus maintenance add real money that scales with how much you drive. A useful budgeting habit is to treat the true monthly cost of a car as the loan payment plus roughly 30–50% on top — so the $565 payment in our example represents a $750–$850 monthly commitment in practice.
That is also why the 20/4/10 rule of thumb — 20% down, no more than a 4-year term, total vehicle costs under 10% of gross income — is stricter than what dealers will approve you for. Financing approval measures what you can technically repay; the rule measures what won't crowd out saving. Our guide on how much car you can afford works through the rule with examples, and the paycheck calculator gives you the take-home number to apply it to.