Auto Payment Calculator with Trade and Payoff

This auto payment calculator helps you determine your monthly loan payments when factoring in your trade-in value and any payoff amounts. Simply enter your loan details, trade-in value, and payoff amount to get an accurate monthly payment estimate.

How to Use This Calculator

Using this auto payment calculator is simple. Follow these steps:

Enter the total loan amount you're requesting
Input your estimated trade-in value (if applicable)
Add any payoff amount from your current vehicle (if applicable)
Enter the interest rate and loan term in months
Click "Calculate" to see your estimated monthly payment

The calculator will then display your estimated monthly payment, total interest paid, and a breakdown of your loan payments over time.

Formula Explained

The auto payment calculator uses the standard auto loan payment formula:

Auto Loan Payment Formula

Monthly Payment = P × (r(1 + r)^n) / ((1 + r)^n - 1)

Where:

P = Principal loan amount (after trade-in and payoff)
r = Monthly interest rate (annual rate divided by 12)
n = Number of payments (loan term in months)

First, the calculator adjusts the principal loan amount by subtracting your trade-in value and payoff amount. Then it applies the standard auto loan payment formula to determine your monthly payment.

Worked Example

Let's walk through an example to see how this calculator works:

Example Scenario

You want to finance a $25,000 car loan with a 4.5% annual interest rate over 60 months. You have a $3,000 trade-in and need to pay off $2,000 from your current vehicle.

Original loan amount: $25,000
Trade-in value: $3,000
Payoff amount: $2,000
Adjusted principal: $25,000 - $3,000 - $2,000 = $18,000
Monthly interest rate: 4.5% / 12 = 0.375% or 0.00375
Number of payments: 60

Plugging these values into the formula:

Calculation

Monthly Payment = $18,000 × (0.00375(1 + 0.00375)^60) / ((1 + 0.00375)^60 - 1)

Monthly Payment ≈ $342.50

So your estimated monthly payment would be $342.50, with a total interest of $1,700 over the life of the loan.

Frequently Asked Questions

How does the trade-in value affect my monthly payment?

The trade-in value reduces the total amount you need to finance. The more you can trade in, the lower your monthly payment will be. The calculator automatically subtracts the trade-in value from your loan amount before calculating payments.

What is the payoff amount and how does it work?

The payoff amount represents money you need to pay off from your current vehicle. This amount is also subtracted from your loan amount, reducing the total amount you need to finance. The calculator includes this in the principal calculation.

Is the interest rate before or after taxes?

The interest rate entered should be the annual percentage rate (APR) before taxes. The calculator uses this rate to determine your monthly payment. Note that some states may require you to pay sales tax on the total loan amount.