🚗 Auto Loan Calculator: Monthly Car Payment, Interest and Total Cost
By ToolNimba Finance Team · Reviewed by ToolNimba Editorial Review, personal finance content · Updated 2026-06-24
This calculator gives an estimate only. Your real car payment depends on the exact APR you qualify for, dealer and registration fees, gap insurance or extended warranties rolled into the loan, and how your state taxes the purchase (some tax the price before a trade-in credit, some after). The result is not financial advice. Confirm the final figures in your loan agreement and speak to a qualified adviser before borrowing.
This auto loan calculator works out the monthly payment on a car loan, plus the total interest and total cost over the term. Enter the vehicle price, your down payment and trade-in value, the sales tax rate, the APR and the loan term in months. It subtracts your cash and trade-in, adds the sales tax, then applies the standard amortization formula so you can see what the car will really cost before you sign at the dealership.
What is the Auto Loan Calculator?
An auto loan is an amortizing loan: you borrow a fixed amount and repay it in equal monthly payments that each cover the interest due that month plus a slice of the principal. The amount you actually finance is not the sticker price. It is the price plus sales tax and any dealer fees, minus your down payment and minus any trade-in credit. Lowering that financed amount, by putting more cash down or trading in a vehicle, is the single most direct way to shrink both your monthly payment and the total interest you pay.
The monthly payment is found with the reducing-balance formula M = A x r x (1 + r)^n / ((1 + r)^n - 1), where A is the amount financed, r is the monthly rate (the APR divided by 12 and by 100) and n is the term in months. Because interest is charged only on the balance you still owe, the split inside each payment changes over time: early payments are mostly interest, and later ones are mostly principal. This is why a longer term feels cheaper month to month but costs much more in total interest, and why making extra principal payments early in the loan saves the most.
APR and term are the two levers that move the cost most. A higher APR raises every payment, and even one or two percentage points adds up to hundreds or thousands of dollars over a five or six year loan. The rate you are offered is driven largely by your credit score: in early 2026 average rates ran near 6.4% for new cars and 11.4% for used cars, but a super prime borrower (score above about 781) might see roughly 5% on a new car while a deep subprime borrower can be quoted 16% or more. Checking your credit and shopping at least two or three lenders before you set foot in a showroom is often worth more than any negotiation on the price.
Term length is the other big lever. Stretching from 48 to 72 months drops the monthly figure but keeps you in debt, and often underwater (owing more than the car is worth), for much longer. A common guideline is the 20/4/10 rule: put at least 20% down, finance for no more than four years, and keep all transportation costs (payment, insurance, fuel and maintenance) under 10% of your gross monthly income. The rule is harder to hit as car prices rise, but it is still a useful sanity check that the payment this tool shows fits comfortably in your budget rather than just barely clearing your bank balance each month.
Sales tax treatment also matters and varies widely by state. Many states tax the price after subtracting the trade-in, which lowers the taxable amount and can save several hundred dollars, while others tax the full purchase price and a handful charge no sales tax at all. This tool applies tax to the vehicle price, so if your state gives a trade-in tax credit, lower the tax rate slightly to approximate it. Remember too that the monthly payment is not the full cost of ownership: insurance, fuel, registration, maintenance and depreciation all add up, and a cheap-looking payment on a long term can hide an expensive car overall.
Finally, think about how the loan fits the rest of your money. Rolling negative equity from an old loan, gap insurance or an extended warranty into the new loan raises the amount financed and the interest you pay on it. If rates fall or your credit improves after you buy, refinancing the remaining balance at a lower APR can cut the payment without extending ownership. Use this calculator to compare a few scenarios side by side, down payment, term and rate, before you commit, so the figure you sign for is the one you actually chose.
When to use it
- Working out the monthly payment on a new or used car before you visit the dealer.
- Comparing a 48, 60 and 72 month term to see how much extra interest a longer loan costs.
- Checking how a bigger down payment or a trade-in changes your payment and total cost.
- Sanity-checking a dealer financing offer against your own bank or credit union quote.
- Testing whether a payment fits the 20/4/10 affordability guideline for your income.
- Estimating how much a lower APR from improving your credit score would save you.
How to use the Auto Loan Calculator
- Enter the vehicle price (the agreed purchase price before tax).
- Enter your down payment and the value of any trade-in.
- Enter your sales tax rate and the APR your lender is offering.
- Enter the loan term in months, then read off the monthly payment, total interest and total cost.
- Change one input at a time (term, down payment or APR) to compare scenarios side by side.
Formula & method
Worked examples
A $30,000 vehicle, $5,000 down, no trade-in, 7% sales tax, 6% APR, 60 month term.
- Sales tax = 30,000 x 7 / 100 = $2,100
- Amount financed = 30,000 + 2,100 - 5,000 - 0 = $27,100
- Monthly rate r = 6 / 12 / 100 = 0.005
- (1 + r)^n = 1.005^60 = 1.348850
- Payment = 27,100 x 0.005 x 1.348850 / (1.348850 - 1) = $523.92
- Total cost = 523.92 x 60 = $31,435.14
- Total interest = 31,435.14 - 27,100 = $4,335.14
Result: Payment about $523.92/mo, total interest about $4,335.14, total cost about $31,435.14
A $25,000 vehicle, $2,000 down, $3,000 trade-in, 8% sales tax, 5.5% APR, 48 month term.
- Sales tax = 25,000 x 8 / 100 = $2,000
- Amount financed = 25,000 + 2,000 - 2,000 - 3,000 = $22,000
- Monthly rate r = 5.5 / 12 / 100 = 0.0045833
- (1 + r)^n = 1.0045833^48 = 1.245451
- Payment = 22,000 x 0.0045833 x 1.245451 / (1.245451 - 1) = $511.64
- Total cost = 511.64 x 48 = $24,558.84
- Total interest = 24,558.84 - 22,000 = $2,558.84
Result: Payment about $511.64/mo, total interest about $2,558.84, total cost about $24,558.84
How credit score changes the cost: a $28,000 amount financed over 60 months at two different rates, a super prime 5% APR versus a subprime 14% APR.
- At 5% APR: r = 0.0041667, (1 + r)^60 = 1.283359, payment = 28,000 x 0.0041667 x 1.283359 / 0.283359 = $528.46
- Total interest at 5% = 528.46 x 60 - 28,000 = $3,707.60
- At 14% APR: r = 0.0116667, (1 + r)^60 = 2.005610, payment = 28,000 x 0.0116667 x 2.005610 / 1.005610 = $651.45
- Total interest at 14% = 651.45 x 60 - 28,000 = $11,087.00
Result: The subprime borrower pays about $123 more a month and roughly $7,379 more in total interest on the identical car, which is why improving your credit before buying matters.
How the loan term changes a $25,000 amount financed at 6% APR
| Term | Monthly payment | Total interest | Total cost |
|---|---|---|---|
| 36 months | $760.55 | $2,379.74 | $27,379.74 |
| 48 months | $587.13 | $3,182.03 | $28,182.03 |
| 60 months | $483.32 | $3,999.20 | $28,999.20 |
| 72 months | $414.32 | $4,831.20 | $29,831.20 |
Typical average auto loan APR by credit tier (early 2026, varies by lender and market)
| Credit tier | Score range | New car APR | Used car APR |
|---|---|---|---|
| Super prime | 781 to 850 | about 5.0% | about 6.8% |
| Prime | 661 to 780 | about 6.7% | about 9.1% |
| Near prime | 601 to 660 | about 9.6% | about 14.0% |
| Subprime | 501 to 600 | about 13.2% | about 18.9% |
| Deep subprime | 300 to 500 | about 15.8% | about 21.6% |
The 20/4/10 affordability rule of thumb
| Guideline | Target | Why it helps |
|---|---|---|
| Down payment | At least 20% of price | Reduces amount financed and avoids being underwater |
| Loan term | No longer than 4 years (48 months) | Limits total interest and shortens time owing the balance |
| Transport cost | Under 10% of gross monthly income | Keeps payment plus insurance, fuel and upkeep affordable |
Common mistakes to avoid
- Choosing a long term just to lower the payment. Stretching from 48 to 72 months on a $25,000 loan at 6% drops the payment by about $173 but adds roughly $1,650 in total interest, and keeps you owing the balance for two extra years.
- Forgetting tax and fees in the financed amount. The amount you borrow includes sales tax (and often dealer, title and registration fees), not just the sticker price. Leaving them out understates both the payment and the total cost.
- Comparing loans by monthly payment instead of APR. A dealer can lower the monthly payment by lengthening the term while charging a higher rate. Compare the APR and the total interest, not just the payment, to see which loan is actually cheaper.
- Assuming the trade-in lowers your taxable amount. Some states tax the price after subtracting the trade-in, others tax the full price. This tool taxes the vehicle price, so adjust the tax rate if your state gives a trade-in tax credit.
- Ignoring the full cost of ownership. The loan payment is only part of the bill. Insurance, fuel, registration, maintenance and depreciation can easily add several hundred dollars a month, so budget for those before deciding what you can afford.
- Rolling negative equity or extras into the loan blindly. Folding an old loan balance, gap insurance or an extended warranty into the new loan raises the amount financed and the interest charged on it, and can leave you underwater from day one.
Glossary
- Amount financed
- The sum you actually borrow: the vehicle price plus sales tax and fees, minus your down payment and trade-in.
- APR
- Annual Percentage Rate, the yearly cost of the loan including interest, used to derive the monthly rate.
- Down payment
- The cash you pay upfront, which reduces the amount you need to finance.
- Trade-in value
- The credit a dealer gives you for your old vehicle, applied against the new purchase.
- Amortization
- Repaying a loan in equal installments that each cover interest plus a portion of principal until the balance reaches zero.
- Underwater
- Owing more on the loan than the car is currently worth, common early in a long term loan or after rolling in negative equity.
- Gap insurance
- Coverage that pays the difference between what you owe and the car value if it is totaled or stolen while you are underwater.
- Negative equity
- The leftover balance on an old car loan that exceeds the trade-in value, which can be rolled into the new loan.
Frequently asked questions
How is my monthly car payment calculated?
The calculator first works out the amount financed (price plus sales tax, minus down payment and trade-in), then applies the amortization formula M = A x r x (1 + r)^n / ((1 + r)^n - 1), where r is the APR divided by 12 and 100, and n is the term in months. Enter your figures and it updates instantly.
How much should I put down on a car?
A common guideline is at least 20% down on a new car and 10% on a used one. A larger down payment lowers the amount financed, reduces your monthly payment and total interest, and helps you avoid being underwater early in the loan. Put down as much as you comfortably can without draining your emergency savings.
Does a bigger down payment lower my payment?
Yes. A larger down payment reduces the amount you finance, which lowers both the monthly payment and the total interest you pay. It also reduces the risk of being underwater, owing more than the car is worth, in the early part of the loan.
What APR will I get on a car loan?
Your APR depends mostly on your credit score, plus the loan term, the lender and whether the car is new or used. In early 2026 averages ran near 6.4% for new cars and 11.4% for used cars, with super prime borrowers seeing around 5% and subprime borrowers 13% or more. Check your credit and get quotes from a bank or credit union before accepting dealer financing.
Is it better to take a longer loan term?
A longer term lowers the monthly payment but increases total interest, because you owe the balance for longer. On a $25,000 loan at 6%, going from 48 to 72 months saves about $173 a month but adds roughly $1,650 in interest. Pick the shortest term you can comfortably afford.
How does APR affect the cost?
APR is the yearly interest rate on the loan. A higher APR raises every payment and the total cost. On a $28,000 loan over 60 months, moving from a 5% to a 14% rate adds about $123 a month and roughly $7,379 in total interest, so shopping rates with several lenders is worth the effort.
Is sales tax charged before or after my trade-in?
Sales tax rules vary by state. Many states tax the price after subtracting the trade-in (which lowers the tax), while others tax the full price and a few charge none. This calculator applies tax to the vehicle price, so if your state gives a trade-in tax credit, lower the tax rate to approximate it.
Does the total cost include my down payment?
No. The total cost shown is the sum of all your monthly payments on the amount financed, which already excludes your down payment and trade-in. Add your down payment back if you want the total out of pocket cost of owning the car.
What is the 20/4/10 rule for buying a car?
It is a budgeting guideline: put at least 20% down, finance for no more than 4 years, and keep total transportation costs (payment, insurance, fuel and maintenance) under 10% of your gross monthly income. It is a quick way to check that a payment from this calculator actually fits your budget.
Can I refinance my car loan later to save money?
Yes. If interest rates drop or your credit score improves after you buy, refinancing the remaining balance at a lower APR can reduce your payment or total interest without extending how long you own the car. Compare any application or transfer fees against the interest you would save before refinancing.
Sources
- Auto loans: How to get the best deal , U.S. Consumer Financial Protection Bureau
- Average Car Loan Interest Rates by Credit Score , Experian
- Amortization , Investopedia