How does a trade-in affect my auto loan?

A trade-in reduces the total amount you need to borrow in two ways. First, its value is directly subtracted from the purchase price of the new vehicle. Second, in most states, trading in a vehicle reduces the taxable amount of your new car purchase, which lowers the sales tax you have to pay.

Should I finance my sales tax?

You can often roll your sales tax and registration fees into your auto loan so you don't have to pay them out of pocket at the dealership. However, this means you will be paying interest on your taxes for the duration of the loan, which increases the total cost of the vehicle.

What is a good interest rate for a car loan?

Auto loan interest rates depend heavily on your credit score and whether the vehicle is new or used. Generally, borrowers with excellent credit (720+) can secure rates between 4% and 6% for new cars, while rates for used cars are typically 1-2% higher. Always shop around with multiple lenders or credit unions before visiting the dealership.

Why should I avoid a 72 or 84-month car loan?

While spreading payments over 6 or 7 years lowers your monthly payment, it drastically increases the total interest you pay. Furthermore, cars depreciate quickly. With a long loan term, you risk being 'underwater' (owing more than the car is worth) for a significant portion of the loan, which can be problematic if the car is totaled or if you try to sell it.

Finance

Auto Loan Calculator

Calculate your monthly car payment quickly. Factor in vehicle price, trade-in value, down payment, and sales tax to find the true cost of your auto loan.

The Auto Loan formula

Your monthly car payment is calculated using the amortization formula for an installment loan:

 M = P × [ r(1 + r)^n ] / [ (1 + r)^n - 1 ] 

M Monthly Payment
P Principal Loan Amount (Price - Trade in - Down Payment + Taxes)
r Monthly interest rate (Annual Rate / 12 / 100)
n Total number of months (Term)

Note: Sales tax is calculated on the vehicle price after trade-in value is deducted (in most states).

How to Estimate Your Car Payment

Buying a car involves much more than just negotiating the sticker price. To truly understand what a vehicle will cost you, you must factor in the trade-in value of your current vehicle, your down payment, local sales tax, and the interest rate of your loan.

Our free auto loan calculator takes the guesswork out of the car buying process. By entering your details into the tool above, you can instantly see your estimated monthly payment, the exact amount you are financing, and the total amount of interest you will pay over the life of the loan.

Breaking Down the Inputs

Vehicle Price: The negotiated purchase price of the car before any taxes, fees, or deductions.
Trade-in Value: The amount the dealer is offering you for your current vehicle. This is deducted from the vehicle price.
Down Payment: The amount of cash you are putting down upfront. A larger down payment reduces your loan amount and protects you from negative equity.
Loan Term: How long you have to repay the loan, usually expressed in months (e.g., 36, 48, 60). Shorter terms have higher monthly payments but lower total interest costs.
Interest Rate: The annual percentage rate (APR) charged by the lender.
Sales Tax Rate: Your local state or county sales tax rate. In many states, this tax is applied after the trade-in value is deducted from the vehicle price.

How Auto Loans Work

An auto loan is a secured loan, meaning the vehicle itself acts as collateral. If you fail to make your payments, the lender has the right to repossess the car. Because the loan is secured by an asset, auto loan interest rates are typically lower than unsecured personal loans or credit cards.

Calculating the Financed Amount

Before calculating the monthly payment, the calculator must determine exactly how much money you actually need to borrow. This is known as the Loan Amount or the Amount Financed.

The formula for the loan amount is generally: Loan Amount = (Vehicle Price - Trade-in Value) + Sales Tax - Down Payment

Note that sales tax is typically calculated on the difference between the vehicle price and the trade-in value. If you buy a $30,000 car and trade in a $10,000 car, you only pay sales tax on the remaining $20,000.

The Monthly Payment Formula

Once the loan amount is established, the monthly payment ($M$) is calculated using standard amortization mathematics:

M = P * [ r(1 + r)^n ] / [ (1 + r)^n - 1 ]

Where:

$P$ = Principal Loan Amount
$r$ = Monthly interest rate (Annual rate divided by 12, then divided by 100)
$n$ = Loan term in months

Real World Example

Imagine you are buying a used car for $25,000. You have a trade-in worth $5,000 and are putting down $2,000 in cash. Your local sales tax is 7%, and you’ve secured a 60-month loan at 5.99% APR.

Calculate the taxable amount: $25,000 - $5,000 = $20,000.
Calculate the sales tax: 7% of $20,000 = $1,400.
Calculate the final loan amount ($P$): $20,000 + $1,400 tax - $2,000 down payment = $19,400.
Calculate the monthly payment ($M$): Using the formula above for $19,400 over 60 months at 5.99%, the payment comes out to $374.88.

Over the 5 years, you will pay a total of $3,092 in interest. The total cost of acquiring the vehicle—including your trade-in equity, down payment, sales tax, principal, and interest—will be over $29,000.

If you are exploring other financial scenarios, check out our personal loan calculator for unsecured borrowing, or our mortgage calculator if you are prioritizing buying a home over a vehicle.

Tips for Getting the Best Auto Loan

To minimize the total cost of your next vehicle purchase, always get pre-approved for financing from a bank or credit union before stepping foot in a dealership. Dealerships often mark up interest rates to make a profit on the financing. By walking in with a pre-approval, you force the dealer to beat your existing rate, ensuring you get the best deal possible. Additionally, aim to keep your loan term at 60 months or less to avoid paying excessive interest on a depreciating asset.

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Results are estimates for educational purposes only and may not reflect all factors in your specific situation. This is not financial advice. Consult a qualified financial adviser for personalised guidance.