Auto Loan Interest Calculator

An auto loan interest calculator helps you determine your monthly payments, total interest paid, and loan breakdown. Whether you're shopping for a new car or refinancing, this tool provides quick, accurate results based on your loan amount, interest rate, and term.

How to Use This Calculator

Using our auto loan interest calculator is simple:

Enter the loan amount you're requesting
Input the annual interest rate (APR)
Select the loan term in years
Click "Calculate" to see your results

The calculator will display your monthly payment, total interest paid over the life of the loan, and the total amount repaid. You can also view a breakdown of how much goes toward principal versus interest each month.

Formula Used

The calculation uses the standard auto loan payment formula:

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

Where:

P = Principal loan amount
r = Monthly interest rate (annual rate ÷ 12)
n = Number of payments (loan term in years × 12)

This formula accounts for the fact that each monthly payment includes both principal and interest, with the interest portion decreasing over time as the principal balance is reduced.

Worked Example

Let's calculate a $25,000 auto loan at 4.5% APR over 5 years:

Principal (P) = $25,000
Annual interest rate = 4.5% or 0.045
Monthly interest rate (r) = 0.045 ÷ 12 = 0.00375
Number of payments (n) = 5 × 12 = 60

Plugging these into the formula:

Monthly Payment = $25,000 × (0.00375(1 + 0.00375)^60) / ((1 + 0.00375)^60 - 1)

Calculating this gives a monthly payment of approximately $454.23

Over 5 years, you would pay $27,254.80 in total interest, with a total repayment of $52,254.80.

Frequently Asked Questions

What is the difference between APR and interest rate?

APR (Annual Percentage Rate) is the total annual cost of credit, including any fees. The interest rate is the portion of APR that applies to the unpaid balance. APR is always higher than the interest rate because it includes fees.

How does loan term affect my monthly payment?

A longer loan term means lower monthly payments but more total interest paid over the life of the loan. A shorter term results in higher monthly payments but less total interest. The optimal term depends on your financial situation and goals.

Can I pay extra toward my loan?

Yes, paying extra toward your loan principal can save you money in interest. Each additional payment reduces the principal balance faster, decreasing the total interest paid. Some lenders offer prepayment penalties, so check your loan agreement.