Auto Loan Amortization Calculator

See how extra payments can save you thousands on your car loan.

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How Auto Loan Amortization Works

Auto loan amortization is the process of paying off your vehicle debt over time through regular installments. Each payment is divided into two parts: interest (the cost of borrowing) and principal (the actual balance of the loan).

The Math Behind the Payment

Lenders use the following formula to determine your fixed monthly payment ($M$):

M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]

Where $P$ is the principal, $i$ is the monthly interest rate (APR / 12), and $n$ is the total number of months.

The Power of Extra Payments

When you make an extra monthly payment or a one-time lump sum, that entire amount is usually applied directly to the principal balance. This reduces the balance faster, which in turn reduces the amount of interest calculated in every subsequent month. As shown in our calculator, even a modest $50 extra per month can shave several months off a 60-month loan and save hundreds in interest charges.

Frequently Asked Questions

Most modern auto loans in the US do not have prepayment penalties, but you should always check your specific loan agreement before making large extra payments.

Standard practice is that payments first cover any outstanding interest, and the remainder goes to the principal. Extra payments are typically applied 100% to the principal.

The savings depend on your APR and remaining term. On a $30,000 loan at 6% for 60 months, an extra $100/month can save over $500 in interest and finish the loan 10 months early.
Statutory Warning: Use these calculations for informational purposes only. Do not make financial, legal, or planning decisions based solely on the results of this calculator. Actual lender calculations may vary based on compounding frequency and fee structures.