Estimate your monthly car payment, total interest, and overall loan cost based on price, down payment, trade-in, tax, and interest rate.
Enter the vehicle's price, any down payment or trade-in value, your local sales tax rate, the loan term in months, and the annual interest rate offered by your lender. Click "Calculate Payment" to see your estimated monthly payment, total interest, and overall loan cost.
The calculator first finds the amount financed: vehicle price, plus sales tax on the price after trade-in, minus your down payment and trade-in value. It then applies the standard installment loan formula: M = P × [r(1+r)^n] / [(1+r)^n - 1], where P is the amount financed, r is the monthly interest rate (annual rate divided by 12), and n is the number of monthly payments.
A $28,000 car with a $3,000 down payment, no trade-in, 6.5% sales tax, financed over 60 months at 5.9% interest results in an amount financed of roughly $26,625, giving a monthly payment near $514, with total interest of about $4,825 over the life of the loan.
Does the calculator include sales tax? Yes, tax is applied to the price after subtracting your trade-in, then added to the financed amount, matching how most dealerships structure the deal.
Can I use this for a used car loan? Yes, the same formula applies to new or used vehicle loans; just enter the agreed purchase price and your loan terms.
It uses the standard loan amortization formula based on the loan amount (price minus down payment/trade-in), interest rate, and loan term in months.
Only if you add them to the loan amount or enter them separately — sales tax, registration, and dealer fees can significantly affect the true amount financed.
A larger down payment reduces the amount financed, which lowers both your monthly payment and the total interest paid over the loan.