Auto Loan Payment & Amortization Calculator

Calculate your monthly car payment including sales tax, trade-in value, down payment, and fees. See your full amortization schedule and total interest cost.

Mathematical Audit

Auto Loan Payment Formula

The calculator first determines the amount you need to finance by combining the vehicle price, sales tax, and any extra fees, then subtracting your down payment and trade-in value. It then applies the standard loan amortization formula to find your fixed monthly payment.

Sales Tax = (Vehicle Price − Trade-In Value) × Sales Tax Rate
Amount Financed = Vehicle Price − Down Payment − Trade-In Value + Sales Tax + Fees
Monthly Rate (r) = APR ÷ 12
Monthly Payment = Amount Financed × [r × (1 + r)^n] ÷ [(1 + r)^n − 1]
Total Interest = (Monthly Payment × n) − Amount Financed

Most U.S. states allow your trade-in value to reduce the amount of the purchase price subject to sales tax, which this calculator assumes. If your state taxes the full price regardless of trade-in, set the trade-in value to 0 and add it as extra down payment instead. Fees such as documentation, title, and registration are added to the financed amount unless paid in cash.

Operational Guide

How to Use the Auto Loan Payment Calculator

1

Enter the vehicle price

Input the negotiated price of the new or used vehicle before tax and fees.

2

Add your down payment and trade-in value

Enter any cash down payment and the value your dealer offers for your trade-in vehicle.

3

Set your sales tax rate and extra fees

Enter your local sales tax percentage and any documentation, title, or registration fees rolled into the loan.

4

Choose your APR and loan term

Enter the annual percentage rate offered by your lender and select a loan term between 24 and 84 months.

5

Calculate and review your results

View your estimated monthly payment, total interest paid, total cost, and a year-by-year amortization chart.

Real-World Scenario Example

"A buyer purchases a $35,000 car with a $5,000 down payment and a $3,000 trade-in, in a state with 6.5% sales tax, financing $500 in fees over 60 months at 6.5% APR."

Inputs

vehiclePrice:35000
downPayment:5000
tradeInValue:3000
salesTaxRate:6.5
apr:6.5
loanTermMonths:60
fees:500

Result

The amount financed is $29,580 (including $2,080 in sales tax). The monthly payment is $578.77, totaling $34,726 over the life of the loan, including $5,146 in interest.

Important Disclaimer

This calculator provides estimates for educational purposes only and does not constitute financial advice. Actual loan terms, taxes, fees, and APR depend on your lender, credit profile, state and local tax rules, and dealer add-ons. Confirm exact figures with your lender's official loan documents before signing.

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