Auto Loan Calculator
Work out your monthly car payment from price, down payment, trade-in, sales tax, rate and term.
Updated 20 Jun 2026 · Free · No sign-up
Sales tax is applied to the price minus trade-in (typical in most US states). Adjust if your state taxes differently.
Car dealers love to talk in monthly payments because a small monthly number can hide a large total cost. This auto loan calculator shows you the real picture: your monthly payment and the total interest you’ll pay, factoring in your down payment, trade-in, and sales tax. Know your number before you walk onto the lot, and you’ll negotiate from a much stronger position.
How the auto loan calculator works
The amount you actually finance is the vehicle price plus sales tax, minus your down payment and any trade-in value. In most US states, sales tax is charged on the price after the trade-in is deducted, which can save you a meaningful amount. The calculator then applies the standard loan-payment formula to that financed amount using your APR and term to find the monthly payment, and multiplies it out to show total interest.
The formula
The monthly payment uses M = P × r × (1 + r)n ÷ ((1 + r)n − 1), where P is the amount financed, r is the monthly rate (APR ÷ 12 ÷ 100), and n is the number of months. Total interest is simply the sum of all payments minus the amount you financed.
A worked example
On a $32,000 car with $4,000 down, no trade-in, 7% sales tax, a 7.5% APR and a 60-month term, you finance about $30,240 (including roughly $2,240 in tax), giving a monthly payment near $606 and total interest of about $6,100 over five years. Stretching to a 72- or 84-month loan would lower the monthly payment but pile on hundreds more in interest — a trade-off worth seeing clearly.
Tips for a cheaper car loan
Shop your rate before visiting the dealer — a pre-approval from your bank or credit union gives you leverage and a benchmark. Put more down if you can, to finance less. Keep the term as short as your budget allows. And negotiate the price of the car itself, not the monthly payment, so the dealer can’t hide a longer term or higher rate inside a “comfortable” monthly figure. For other loans, try our personal loan calculator.
Frequently asked questions
How is my car loan payment calculated?
The calculator finds the amount financed (price plus sales tax, minus down payment and trade-in), then applies the standard loan formula using your APR and term in months. It shows the monthly payment along with total interest and total of all payments.
Is sales tax charged before or after my trade-in?
In most US states, sales tax is calculated on the vehicle price after subtracting your trade-in value, which lowers the tax you pay. A few states tax the full price. This calculator deducts the trade-in first; adjust the tax rate if your state works differently.
Should I choose a longer loan term for a lower payment?
A longer term lowers your monthly payment but increases total interest and keeps you owing more than the car is worth for longer. Generally, pick the shortest term you can comfortably afford. If a car only fits on a very long loan, it may be too expensive for your budget.
Does this include taxes and fees exactly?
It includes estimated sales tax but not every dealer fee, registration cost, or add-on. Treat the result as a close estimate for planning and negotiating, and confirm the exact figures in your loan paperwork. This is for education only, not financial advice.