Auto Loan Calculator

How the car payment is built

Financing a vehicle happens in two steps. First the calculator works out how much you actually borrow: amount financed = price + sales tax − down payment − trade-in. Sales tax is applied to the vehicle price, then your cash down payment and any trade-in credit reduce the balance. Second, that amount is repaid with equal monthly payments using the standard amortization formula M = P × r ÷ (1 − (1 + r)⁻ⁿ), where P is the amount financed, r is the monthly interest rate (APR ÷ 12 ÷ 100) and n is the number of months in the term. At a 0% promotional rate the payment is simply the amount financed divided evenly across the term.

What raises or lowers the payment

Three levers move the monthly number most. A larger down payment or trade-in cuts the amount financed dollar for dollar, lowering both the payment and the interest you pay. A lower APR reduces the interest portion of every payment. A longer term spreads the balance over more months, which shrinks each payment but increases total interest — a 72-month loan almost always costs more overall than a 48-month loan at the same rate. Watch the total interest and total cost figures, not just the monthly payment, when you compare offers, because dealers often quote the lowest monthly number by stretching the term.

Notes and assumptions

This is a planning estimate. It assumes a simple-interest amortizing loan with no fees rolled into the balance and no add-ons such as gap insurance, extended warranties or documentation fees. Tax rules vary by location: some states tax the price after subtracting the trade-in, which lowers the taxable amount — if that applies to you, reduce the price input to match. Everything is calculated locally in your browser with no account, credit pull or live-rate lookup, so confirm the final contract figures with your lender before signing.