Auto Loan Calculator
Your real car payment for a new or used vehicle — monthly payment, total interest, and total cost, with down payment, trade-in, and sales tax built in. Runs in your browser; nothing is stored.
How the math works
Your monthly payment comes from the standard amortization formula: P × r ÷ (1 − (1 + r)−n) — that is, P times r, divided by one minus (1 + r) raised to the power of negative n — where P is the amount financed, r the monthly interest rate (APR ÷ 12), and n the number of months. The amount financed is the vehicle price plus sales tax, minus your down payment and trade-in. A bigger down payment or trade-in — and a shorter term — cut the interest you pay. Used-car rates run higher than new, so the New/Used toggle starts each at a typical rate you can adjust.
Frequently asked questions
How is a car payment calculated?
The amortization formula above, on the amount financed (price + sales tax − down payment − trade-in). Try your numbers above.
Do new and used cars have different rates?
Yes — used-car APRs are almost always higher. As a rough 2026 guide, new is around 6–7% and used often 10–12%. The toggle sets a typical starting rate; enter your own for an exact figure.
How does a trade-in help?
It lowers the amount you finance like a down payment, and in most states it also cuts your sales tax, since tax is charged after the trade-in credit. This calculator applies that credit by default.
Is a longer term cheaper?
It lowers the monthly payment but raises total interest and the risk of owing more than the car is worth. A 72- or 84-month loan can cost thousands more than a 48- or 60-month loan on the same car.
Estimates for information only — not financial or lending advice. Sales-tax treatment of trade-ins varies by state.