Auto Loan Calculator
Calculate your monthly car payment, total interest, and see a complete amortization schedule. Adjust the inputs to see how different loan terms, down payments, and interest rates affect what you'll pay.
Loan Details
Montana has no statewide vehicle sales tax. Use the optional rate below only for an applicable county option tax.
Loan Summary
Bigger Down Payment Saves More
A 20% down payment instead of 10% can save you thousands in interest and reduce your monthly payment significantly.
Shorter Terms Cost Less Overall
A 60-month loan typically costs $2,000-$4,000 less in interest than a 72-month loan on the same vehicle.
APR Matters More Than You Think
Dropping your APR from 8% to 5% on a $25,000 loan saves over $2,000 in interest across 60 months.
Frequently Asked Questions
How is my monthly auto loan payment calculated?
Your monthly payment uses the standard amortization formula: P × (r(1+r)^n) / ((1+r)^n − 1), where P is the loan principal, r is the monthly interest rate (APR ÷ 12), and n is the number of monthly payments.
Does a longer loan term lower my monthly payment?
Yes — but at a cost. A 72 or 84 month term reduces your monthly payment, but you'll pay significantly more total interest. Shorter terms cost more per month but save money overall.
How much down payment should I put on a car?
A down payment of 10–20% of the vehicle price is generally recommended. A larger down payment reduces your loan principal, lowers your monthly payment, decreases total interest paid, and lowers the risk of being upside-down on the loan.
Is this calculator accurate?
This calculator uses the same amortization formula banks and lenders use. Your actual payment may vary slightly based on fees, insurance products, and the specific terms your lender offers. Use this as a close estimate to plan your budget.