Last updated: March 2026
How to Calculate Your Car Payment
Buying a car is one of the biggest financial decisions most people make regularly, and understanding your monthly payment before visiting the dealership puts you in a much stronger negotiating position. Your car payment depends on three main factors: the loan amount, interest rate, and loan term.
The loan amount is the vehicle price minus your down payment and trade-in value, plus applicable sales tax. If you're buying a $35,000 car with $5,000 down and a $7,000 trade-in, you're financing around $23,000 plus tax. Fees and dealer add-ons can increase this number, so factor those into your calculations.
Your interest rate depends primarily on your credit score, but also on the loan term and whether the car is new or used. New cars typically qualify for lower rates because they hold value better as collateral. Rates can vary by 5% or more between excellent and poor credit, which translates to thousands of dollars over the loan's life.
Loan term has a huge impact on both your monthly payment and total cost. A 36-month term means higher monthly payments but far less interest overall. A 72-month term lowers the payment but can cost you thousands more in interest — and you risk owing more than the car is worth (negative equity) if the vehicle depreciates faster than you pay it down.
To get the best deal, get pre-approved before shopping. Check rates from your bank, credit union, and online lenders. Knowing your rate ahead of time prevents dealers from inflating it. And keep total cost — not just monthly payment — as your primary decision metric.
Understanding Auto Loan Interest
Auto loans use simple interest amortization, meaning interest is calculated on the remaining principal balance each month. In the early months, a larger portion of your payment goes toward interest. As the balance decreases, more goes toward paying down the principal.
This is why extra payments are so powerful early in the loan. An extra $100/month on a $30,000 auto loan at 6.5% saves over $1,000 in interest and pays off the loan nearly a year early. Every dollar of extra payment reduces the balance that accrues interest for every remaining month.
The total interest you pay can be shocking. On a $35,000 vehicle financed at 7% for 72 months, you'll pay over $8,000 in interest alone. That's money that could have gone toward your next car, an emergency fund, or investments. Use this calculator to see exactly how much interest you'll pay under different scenarios.
This calculator provides estimates for educational purposes only. Actual loan terms depend on your credit profile, lender, and vehicle. Consult a financial professional for personalized advice.
Frequently Asked Questions
What is a good interest rate for a car loan?
Interest rates vary by credit score, loan term, and whether the vehicle is new or used. In general, rates for new cars range from 4% to 7% for borrowers with good credit. Used car rates are typically 1-2% higher. Excellent credit (750+) can qualify for rates below 4%, while subprime borrowers may see rates above 10%.
How does a down payment affect my car loan?
A larger down payment reduces the amount you finance, which lowers both your monthly payment and total interest paid. Putting 20% down also helps avoid being "upside down" on the loan (owing more than the car is worth). Even 10% down significantly reduces your financing costs.
Should I choose a longer loan term for lower payments?
Longer terms (60-84 months) lower your monthly payment but increase total interest paid substantially. A $30,000 loan at 6.5% costs $2,613 in interest over 36 months but $6,368 over 72 months. Choose the shortest term you can comfortably afford to minimize total cost.
How does a trade-in affect my auto loan?
Your trade-in value is subtracted from the purchase price before financing. If you buy a $35,000 car with a $10,000 trade-in, you finance $25,000. This reduces your monthly payment and total interest. If you owe money on the trade-in, only the equity (value minus payoff) reduces your new loan.
Is it better to finance through a dealer or bank?
Compare both options. Dealers sometimes offer promotional rates (like 0% APR for qualified buyers), but their standard rates may be higher than your bank or credit union. Get pre-approved by your bank first, then see if the dealer can beat that rate. Credit unions often offer the most competitive auto loan rates.
What fees should I watch for in auto financing?
Common fees include documentation fees ($100-800), dealer markup on the interest rate (ask for the "buy rate"), and unnecessary add-ons like extended warranties, gap insurance, and paint protection. Always negotiate these separately from the vehicle price and financing terms.