Finance
Auto Loan Calculator
Calculate monthly car payments, sales taxes, fees, and interest based on dealer pricing and trade-in inputs.
Inputs
Results
Monthly Auto Payment
$0.00
Amount Financed
$0.00
Sales Tax Amount
$0.00
Total Interest Paid
$0.00
Total Cost of Vehicle
$0.00
How It Works
The auto loan calculator takes the initial purchase price of the vehicle, deducts trade-in value and down payment, and adds registration fees and local sales tax to calculate the net amount financed. The monthly payment is then determined using standard amortizing formulas where interest accrues on the outstanding balance, compounded monthly over the selected repayment term (typically 36 to 84 months).
Formula Used
Sales Tax Amount = Max(0, Vehicle Price − Trade-in Value) × Sales Tax %
In many jurisdictions, sales tax is calculated on the net purchase price after subtracting the trade-in allowance. This provides a tax credit for the value of the trade-in vehicle, reducing the taxable portion.
Amount Financed = Vehicle Price − Down Payment − Trade-in Value + Sales Tax Amount + Fees
This equation sums the net vehicle price, tax, and fees to determine the total capital that must be borrowed. The monthly payment is then computed using the standard amortization formula on this financed amount.
Worked Example
Here is a step-by-step example of how these values are calculated:
Vehicle Price
$35,000
Down Payment
$5,000
Trade-in
$2,000
Interest Rate
5.5%
Term
60 Months
Tax
7%
Dealer Fees
$500
Result: Monthly Payment: $541.77. Net Financed: $28,460.00. Tax Paid: $2,310.00. Total Interest: $4,046.20.
Frequently Asked Questions
Is sales tax calculated before or after trade-in?
In most U.S. states, you only pay sales tax on the net cost of the vehicle after your trade-in value has been subtracted. This calculator applies tax to the difference (Price - Trade-In).
How does term length impact auto loan costs?
A shorter term (e.g., 36 or 48 months) means higher monthly payments but lower overall interest charges. A longer term (e.g., 72 or 84 months) lowers monthly output but significantly increases total interest paid.