1
Auto & Vehicle
Auto Loan Calculator — Monthly Car Payment, Interest & Total Cost
See the real monthly payment and lifetime interest before you sign at the dealership
Buying a car is the second-biggest purchase most Americans ever make, and the sticker price is only half the story. What actually hits your budget every month is the loan payment — and that number depends on six things the dealer's finance office juggles all at once: the vehicle price, your down payment, any trade-in, the sales tax in your state, the loan term in months, and the APR (annual percentage rate).
This calculator pulls those pieces together the American way — dollars, percent APR, and a term measured in months (36, 48, 60, 72, even 84). Here's how the math works.
First, find the amount financed (the loan principal). Most states charge sales tax on the price after the trade-in credit, so:
Taxable amount = price − trade-in, then sales tax = taxable amount × tax rate.
Amount financed = price + sales tax − down payment − trade-in.
Then the monthly payment uses the standard amortizing-loan formula:
M = P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1)
where P is the amount financed, r is the monthly rate (APR ÷ 12 ÷ 100), and n is the number of months.
Worked example. A $30,000 car, $3,000 down, $2,000 trade-in, 6% sales tax, 60 months, 7% APR. Tax = 6% × (30,000 − 2,000) = $1,680. Amount financed = 30,000 + 1,680 − 3,000 − 2,000 = $26,680. Monthly rate r = 0.07 ÷ 12 = 0.0058333, n = 60, so (1 + r)ⁿ ≈ 1.41763. M = 26,680 × 0.0058333 × 1.41763 ÷ 0.41763 = $528.30 per month. Over 60 months you pay $31,697.76 — that's about $5,018 in interest on top of the loan.
The most common mistake car buyers make is shopping for a monthly payment instead of a total cost. A longer term (72 or 84 months) shrinks the monthly number but balloons the interest and keeps you "upside down" — owing more than the car is worth — for years. Always compare the total interest and total cost, not just the payment. A second trap: forgetting that 0% APR deals are real (the formula returns price ÷ months), but everything else compounds, so even a half-point of APR adds up over a six-year loan.
This calculator gives an informational estimate. Your actual payment, fees, dealer add-ons, and APR depend on the lender and your credit — always confirm the final numbers on your loan contract.
📖 See also: How to Calculate Your Car Payment
Calculator
Fill in the fields and click "Calculate" for instant results.
📰 Formula
• Taxable amount = price − trade-in • Sales tax = taxable amount × (tax rate / 100) • Amount financed (P) = price + sales tax − down payment − trade-in • Monthly rate r = APR / 12 / 100 • Monthly payment M = P × r × (1 + r)^n / ((1 + r)^n − 1) • If APR = 0: M = P / n • Total cost = total of payments + down payment • Total interest = total of payments − amount financed
📰 Formula
• Taxable amount = price − trade-in • Sales tax = taxable amount × (tax rate / 100) • Amount financed (P) = price + sales tax − down payment − trade-in • Monthly rate r = APR / 12 / 100 • Monthly payment M = P × r × (1 + r)^n / ((1 + r)^n − 1) • If APR = 0: M = P / n • Total cost = total of payments + down payment • Total interest = total of payments − amount financed
🧪 Worked examples
2
Example 2
3
Example 3
4
Example 4
⚠️ Common mistakes
- Shopping for a low monthly payment instead of the lowest total cost.
- Forgetting sales tax — it's usually rolled into the amount you finance.
- Entering the APR as a decimal (0.07) instead of a percent (7).
- Stretching to 72 or 84 months and ignoring how much extra interest that adds.
💡 Tips
- Compare total interest across terms, not just the monthly payment — a longer loan almost always costs more.
- A larger down payment or trade-in directly reduces the amount financed and the interest you pay.
- Get pre-approved by your own bank or credit union first, then let the dealer try to beat that APR.
Embed this calculator on your site
Copy the code below and paste it into the HTML of your site or blog.
<iframe src="https://www.calcnimbus.com/embed/auto-loan-calculator" width="100%" height="500" frameborder="0" style="border:1px solid #eee;border-radius:12px"></iframe>
❓ Frequently asked questions
How do I calculate a monthly car payment?
Use M = P × r × (1 + r)^n ÷ ((1 + r)^n − 1), where P is the amount financed, r is the APR divided by 12 (as a decimal), and n is the number of months. For a $26,680 loan at 7% APR over 60 months, that's about $528.30 per month.
Does the amount financed include sales tax?
Usually, yes. Most buyers roll sales tax into the loan. The amount financed = vehicle price + sales tax − down payment − trade-in. In most states the tax is charged on the price after the trade-in credit.
How much does a $30,000 car cost per month?
It depends on your down payment, term, and APR. With $3,000 down, a $2,000 trade-in, 6% tax, 7% APR, and a 60-month term, you'd finance about $26,680 and pay roughly $528 a month.
Is a 60-month or 72-month car loan better?
A 60-month loan has a higher monthly payment but less total interest and faster equity. A 72-month loan lowers the payment but costs more overall and keeps you upside down longer. Pick the shortest term you can comfortably afford.
How does a down payment lower my payment?
Every dollar you put down reduces the amount financed dollar-for-dollar, so you borrow less and pay interest on a smaller balance. A bigger down payment cuts both the monthly payment and the total interest.
What APR should I expect on an auto loan?
It varies with your credit score, the lender, and whether the car is new or used. Strong credit can land low single-digit APRs; weaker credit runs much higher. Always compare a bank or credit union quote against the dealer's offer.
How is total interest on a car loan calculated?
Total interest = (monthly payment × number of months) − amount financed. It's the difference between everything you pay over the loan and the principal you originally borrowed.
Does a trade-in reduce my sales tax?
In most U.S. states, yes — you only pay sales tax on the price after subtracting the trade-in value, which lowers both your tax bill and the amount you finance. A few states tax the full price, so check your state's rule.
What happens to the payment if the APR is 0%?
With a true 0% APR promotion, there's no interest, so the monthly payment is simply the amount financed divided by the number of months. A $20,000 loan over 60 months would be exactly $333.33 per month.