Auto Loan Calculator
Find out exactly how much that new car will cost you. Estimate your monthly payment, total interest, and final cost of ownership before heading to the dealership.
Vehicle Details
Out-the-Door Price
Taxes & Dealership Fees
In most states, trading in a car reduces your taxable amount. Your trade-in is saving you $350 in sales tax!
Estimated Monthly Payment
$599
Financed Amount: $29,900
Out-the-Door Price
$32,900
Car + Tax + Fees - Trade
Total Interest Paid
$6,048
Over 60 months
What is an Auto Loan?
An auto loan allows you to borrow money from a lender (like a bank, credit union, or dealership) to purchase a vehicle. You agree to pay back the borrowed amount, plus interest, over a set period of time—usually between 36 and 72 months.
When financing a car, the vehicle itself serves as collateral. This means if you fail to make your monthly payments, the lender has the legal right to repossess the car.
- Principal: The actual price of the vehicle minus your down payment and trade-in value, plus any taxes or fees you choose to roll into the loan.
- Interest Rate (APR): The cost of borrowing the money, expressed as an annual percentage.
How to Use the Auto Loan Calculator
- Vehicle Price: Enter the negotiated or sticker price of the car you want to buy.
- Down Payment & Trade-In: Input any cash you plan to put down, and the estimated value of your current car if you plan to trade it in.
- Loan Term: Select how many months you plan to pay off the loan (e.g., 48, 60, or 72 months).
- Interest Rate: Enter the APR you qualify for. (Check your bank or credit union for current pre-approval rates).
- Sales Tax: Enter your local state/county sales tax rate.
The Auto Loan Formula
Car loans are amortized, meaning you pay a fixed amount every month, but the portion going toward interest versus principal changes over time. The monthly payment formula is:
| Variable | Meaning |
|---|---|
| M | Your fixed Monthly Payment. |
| P | The Principal loan amount (Price - Down Payment - Trade-in + Taxes). |
| r | The monthly interest rate (Annual rate divided by 12). |
| n | The total number of months (e.g., 60). |
Example Auto Loan Calculation
Let's walk through exactly how the math works for buying a $35,000 car with a $5,000 down payment, financed over 60 months at 6.5% interest with a 7% sales tax.
Step 1: Calculate the Total Loan Amount (Principal)
First, subtract your down payment and add the taxes. The 7% sales tax on $35,000 is $2,450.
Step 2: Calculate the Monthly Payment
Using the amortization formula with our Principal ($32,450), monthly rate (6.5% / 12 = 0.005416), and term (60 months), we find the fixed monthly payment.
Step 3: Total Cost Breakdown
Understanding Your Results
It is very common for buyers to only look at the "Monthly Payment" and ignore everything else. Dealerships know this, and will often try to sell you a car based entirely on getting your monthly payment to a certain number.
The "Total Cost" Trap
If you tell a dealer "I can only afford $400 a month", they might give you a $400 payment by extending your loan to 84 months (7 years). While the payment fits your budget, you will end up paying thousands of extra dollars in interest, and you will likely owe more on the car than it is worth for many years. Always negotiate based on the Total Cost of the Vehicle, not the monthly payment.
Important Limitations
This calculator provides a highly accurate estimate based on standard amortization, but it cannot predict every dealer fee. Dealerships often tack on "Document Fees", "Destination Charges", or mandatory warranties that can add $500 to $2,000 to the loan amount. Always ask for an "Out-the-Door" price breakdown before signing.
Common Auto Financing Mistakes
1. Financing your taxes and fees
When you roll your sales tax and dealer fees into the loan, you are paying interest on those taxes for the next 5 years. Always try to pay your taxes and fees in cash on the day of purchase.
2. Not getting pre-approved
Never walk into a dealership without financing already lined up. Go to your local credit union or bank and get a pre-approval letter. You can use this as leverage to force the dealer to beat your rate.
3. Rolling over negative equity
If you owe $15,000 on your current car, but the dealer only gives you a $10,000 trade-in credit, you have $5,000 in "negative equity". Rolling that $5,000 debt into your new car loan guarantees you will be severely upside-down on the new vehicle the moment you drive it away.
Frequently Asked Questions
How much should I put down on a car?
Experts traditionally recommend putting down 20% of the vehicle's purchase price. This helps offset initial depreciation (the 'drive-off-the-lot' drop in value) and ensures you don't end up 'upside down' (owing more than the car is worth) on your loan.
What is a good auto loan interest rate?
Auto loan rates vary heavily based on your credit score and whether the car is new or used. For excellent credit (780+), you might see rates around 5-6% for new cars in 2026. For lower credit scores, rates can easily exceed 10-15%.
Does a longer loan term save me money?
No. A longer loan term (like 72 or 84 months) will lower your monthly payment, making the car feel more affordable month-to-month. However, you will pay significantly more in total interest over the life of the loan. Aim for 48 to 60 months if possible.
How does sales tax affect my loan?
In most states, sales tax is calculated on the price of the car (often minus the value of your trade-in). If you don't pay the tax out-of-pocket in cash, it is rolled into your total loan amount, meaning you will pay interest on the tax for the next 5 years.
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Author / Reviewer: Anmol Giri
Last updated: August 2026