Cars Finance Calculator
Sticker price is not what you finance. Sales tax gets added, your down payment and trade-in come off, and only then does the interest rate touch the balance. Most car finance calculators skip the tax math or hide the total interest, leaving you with a monthly payment and no sense of the deal. This car finance calculator builds the amount financed the way the contract does, then shows the monthly payment, the total interest, and what the payment means against your income.
Estimate only. Your contract may add title, registration and documentation fees, and trade-in tax treatment varies by state.
Quick Answer
On a $35,000 car with $5,000 down, no trade-in, and 7% sales tax, the amount financed is $32,450. At 6.5% APR over 60 months, the payment is $634.92 a month, the total interest is $5,645, and the full cost of the car including your down payment is $43,095. Interest makes up 14.8% of every dollar paid on the loan.
Key takeaways
- You finance price plus tax, minus down payment and trade-in. A $35,000 car at 7% tax is really $37,450 before your money comes off.
- Keep total car payments (loan plus insurance) under 15% of gross monthly income; under 10% is comfortable. The tool scores the loan payment alone, so add insurance before judging the verdict.
- Dealer financing is a starting bid, not a verdict. Get pre-approved by your bank or credit union first, then let the dealer try to beat it.
- Stretching the worked example to 84 months drops the payment to about $482 but raises total interest to about $8,026, roughly 42% more interest than the 60-month loan.
How a car payment is actually built
The payment follows one equation, but the amount it is applied to is where buyers get surprised. The amount financed equals the negotiated price plus sales tax, minus your down payment, minus your trade-in value. On the worked example: $35,000 times 1.07 is $37,450, minus $5,000 down leaves $32,450 financed. The monthly payment then comes from the standard amortizing loan formula: payment equals principal times the monthly rate times (1 plus monthly rate) to the power of the number of payments, divided by that same power minus one. At 6.5% over 60 months that is $634.92.
1. Price plus tax: $35,000 × 1.07 = $37,450.
2. Minus down payment: $37,450 − $5,000 = $32,450 financed.
3. Monthly rate: 6.5% ÷ 12 = 0.5417% per month; 60 payments.
4. Payment: $634.92 per month; total of payments $38,095; interest $38,095 − $32,450 = $5,645.
5. Full cost: $5,000 down + $38,095 of payments = $43,095.
One honest caveat, worth stating plainly: how sales tax treats a trade-in genuinely varies by state. Many states tax only the price difference after trade-in, which lowers the financed amount; others tax the full price. This calculator taxes the full price by default, the conservative assumption, and the checkbox under the inputs switches to the trade-in-credit treatment. With a $5,000 trade-in on the worked example, the default gives $27,450 financed ($37,450 minus $5,000 down minus $5,000 trade-in), while the trade-in-credit treatment gives $27,100 (($35,000 minus $5,000) times 1.07, minus $5,000 down): $350 less financed, exactly the 7% tax on the trade-in. If you are weighing the trade-in separately, our car trade-in calculator helps you value it before the dealer does, and our car budget calculator works backward from your income to the price you should be shopping.
Illustrative auto loan rates: what your credit tier buys
The rate is the second-biggest lever after the price, and it is priced almost entirely on credit tier. The bands below are illustrative, not lender quotes: they exist so you can see what each tier does to the same $32,450, 60-month example. Your actual offer depends on your credit file, the vehicle, and the lender. Dropping from 9% to 6.5% on the $32,450 example saves about $39 a month and about $2,322 in total interest. Before you sign, check your tier and run the numbers through our car refinancing calculator if you already hold a loan at a rate that no longer matches your credit.
| Credit tier | Illustrative new-car APR | Monthly payment on $32,450 / 60 mo | Total interest |
|---|---|---|---|
| Excellent (750+) | 5.0 to 7.0% | $612 to $643 | $4,292 to $6,103 |
| Good (700-749) | 7.0 to 10.0% | $643 to $689 | $6,103 to $8,918 |
| Fair (640-699) | 10.0 to 14.0% | $689 to $755 | $8,918 to $12,853 |
| Poor (below 640) | 14.0% and up | $755 and up | $12,853 and up |
Used cars typically run about 2 to 3 points above new-car rates at the same tier. The jump from excellent to poor credit can roughly triple the total interest on the same car: about $4,292 at 5% against about $12,853 at 14% on this example.
Dealer financing vs bank vs credit union
Where you borrow matters as much as the rate you are quoted, because the dealer’s finance office can mark up the buy rate the lender actually approved. The Consumer Financial Protection Bureau advises buyers to treat dealer financing as one offer among several and to compare the APR, not just the monthly payment.
| Lender | Strengths | Watch out for |
|---|---|---|
| Dealer financing | Convenient, one stop, same day; access to manufacturer promos (0% APR deals) | Rate markup over the approved buy rate; 0% offers often mean giving up cash rebates |
| Bank | Pre-approval before you shop sets a ceiling; transparent rate tied to your credit file | May not match promo manufacturer rates |
| Credit union | Often the lowest rates in the market; member-owned, less markup incentive | Requires membership eligibility |
The winning play, recommended by the CFPB’s auto-loan guidance, is to arrive pre-approved and make the dealer beat your rate in writing. A 0% manufacturer promo can still lose to a rebate plus bank financing, so price both paths with this calculator before you choose: run the 0% deal with no rebate, then run the rebate as a larger down payment at your bank rate, and compare total interest plus full cost, not the monthly payment alone.
The 84-month trap
Longer terms are the easiest way to afford a car you cannot afford. Stretching the worked example from 60 to 84 months drops the payment from $634.92 to about $482, but total interest climbs from $5,645 to about $8,026, roughly 42% more interest, and you stay underwater, owing more than the car is worth, for most of the loan because new cars lose roughly a fifth of their value in the first year. Financial advisors generally cap auto loans at 60 months. If the car you want only fits at 84 months, the honest answer is a cheaper car, a bigger down payment, or waiting, not a longer loan. Leasing is the other escape hatch people consider; our loan versus lease calculator compares the two paths on total cost rather than monthly payment.
What most car finance calculators get wrong
Three patterns repeat across the ranking tools. First, several ask for the loan amount directly and never build it from price, tax, down payment, and trade-in, which means the number most buyers type in is wrong before the math starts. Second, almost none show total interest prominently; the monthly payment is the hero and the $5,645 of interest is buried or absent, even though it is the number that distinguishes a good deal from an expensive one. Third, none tie the payment to income with an affordability verdict, so a $900 payment looks the same for a $4,000-a-month earner and a $12,000-a-month earner. A fourth gap is subtler: tools that do include sales tax almost never expose the trade-in tax treatment, even though the credit is worth hundreds of dollars on a typical trade-in. This calculator builds the financed amount from the real deal pieces, puts total interest and full cost in the results grid, scores the payment against your income or, without income, against the term-length risk, and lets you switch the trade-in tax treatment with one checkbox. For the running costs after purchase, our car insurance cost per month calculator estimates the insurance half of the affordability guideline.
Frequently asked questions
First build the amount financed: price plus sales tax, minus down payment and trade-in. Then apply the amortizing loan formula using the monthly interest rate (APR divided by 12) and the number of months. For a $35,000 car at 7% tax with $5,000 down, the financed amount is $32,450, and at 6.5% over 60 months the payment is $634.92.
For new cars with excellent credit (750+), 5 to 7% is a typical illustrative band; good credit (700-749) lands around 7 to 10%. Used cars run about 2 to 3 points higher at each tier. Compare any dealer quote against a bank or credit union pre-approval at your tier before you sign.
The common guideline is to keep total car costs, payment plus insurance, under 15% of gross monthly income, with under 10% considered comfortable. On $6,000 a month of income, that means roughly $600 to $900 all-in. Enter your income in this calculator and it will score the loan payment against that guideline automatically.
It is expensive and risky. Longer terms lower the monthly payment but raise total interest sharply and keep you owing more than the car is worth for years, since cars depreciate fastest early. On the worked example, 84 months costs about $8,026 in interest against $5,645 at 60 months. Advisors generally recommend 60 months or less.
The traditional advice is 20% down on a new car or 10% on used, mainly to avoid going underwater since new cars lose roughly a fifth of value in the first year. A bigger down payment also cuts total interest directly. The exception is a genuine 0% promo rate, where keeping cash invested can beat paying down a free loan, but only if you would not otherwise give up a larger rebate.
It depends on the state. Many states give a trade-in credit and tax only the price difference, while others tax the full price. This calculator applies tax to the full price by default, which is the conservative assumption; tick the trade-in credit checkbox if your state taxes only the price after trade-in.
The loan itself charges no interest, but 0% offers usually require giving up a cash rebate. Compare the rebate plus a bank loan against the 0% deal with no rebate using this calculator, and compare total interest plus full cost, not the monthly payment alone.
Yes. Dealers can mark up the buy rate a lender approves, and the CFPB has flagged this markup as a frequent overcharge. Arriving with a bank or credit union pre-approval gives you a rate to beat and removes the markup entirely if the dealer cannot beat it. Always compare APRs, not monthly payments.
Expect documentation fees, title and registration, and sometimes dealer add-ons like paint protection or VIN etching. Add legitimate fees to the vehicle price field in this calculator so they are financed correctly. Question any add-on you did not ask for; most are negotiable or removable.
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References
- Consumer Financial Protection Bureau. Auto loans (steps for getting an auto loan, what is negotiable, and comparing APRs). Accessed October 24, 2026.
- Consumer Financial Protection Bureau. What should I know before I finalize a car or auto loan? (reviewing loan terms and Truth in Lending disclosures before signing). Accessed October 24, 2026.
- Consumer Financial Protection Bureau. Buying a car? Here is what you need to know (shop for the loan before shopping for the car; compare all loan terms, not just the monthly payment). Accessed October 24, 2026.