Enter the vehicle price, down payment, trade-in, sales tax, term and APR to see your monthly car payment and the total interest you'll pay — updated live as you type.
Financing a car comes down to one number: the amount financed. We take the vehicle price, add sales tax, then subtract your down payment and any trade-in value. Whatever is left is what you borrow, and it is repaid through amortization — equal monthly payments split between interest and principal.
The monthly payment uses the standard formula:
M = P · r / (1 − (1 + r)−n)
where P is the amount financed, r is the monthly rate (your APR divided by 12), and n is the term in months. A larger down payment or trade-in lowers P, which lowers both your monthly payment and the total interest you pay.
A note on sales tax: car sales tax rules vary by state. Some states tax the full purchase price, while others tax the price minus your trade-in, and local rates may be added on top. This tool applies your rate to the price after trade-in, so treat the tax and payment as an estimate and confirm the exact figure with your dealer or state.
How is my monthly car payment calculated?
We find the amount financed — price plus tax, minus down payment and trade-in — then apply the amortization formula using your APR divided by 12 and your term in months.
How does a trade-in affect the loan?
A trade-in acts like extra money down: its value is subtracted from what you finance, lowering the payment and total interest. In many states it also reduces the taxable amount.
Is the sales tax figure exact?
Treat it as an estimate. States tax cars differently — some on the full price, some on price minus trade-in — and local rates vary. Confirm the exact amount with your dealer or state.