Vehicle Loan Affordability Calculator
Determine the maximum vehicle purchase price and sticker budget that aligns with your monthly household cash flow. By entering your target monthly car payment, loan term, quoted APR, down payment, trade-in credit, sales tax rate, and dealer documentation fees, this calculator provides instant purchase clarity.
Maximum comfortable monthly loan installment
Repayment period (e.g. 36, 48, 60, 72 months)
Annual interest percentage rate quoted by your lender
Upfront cash savings paid toward vehicle purchase
Net equity value offered for your current car
State or regional vehicle sales tax percentage
Dealer documentation, title, and registration charges
Highest negotiated vehicle sticker price within your monthly budget
How to Use This Calculator
- Establish your target monthly auto payment using the 20/4/10 budgeting rule.
- Enter your expected financing loan duration (e.g. 48 or 60 months).
- Input your pre-approved interest rate from your bank or credit union.
- Enter your cash down payment and vehicle trade-in allowance.
- Include state vehicle sales tax and dealer documentation charges.
- Review your maximum affordable vehicle purchase price before shopping.
Formula & Calculation Methodology
The reverse amortization formula determines maximum borrowable loan principal from your monthly budget. The vehicle purchase price is then solved algebraically after factoring down payment, trade-in tax credits, sales tax, and dealer fees.
Worked Example
Targeting a $550/mo payment over 60 months at 6.5% APR with $4,000 down, $2,500 trade-in, 7% sales tax, and $450 fees
Frequently Asked Questions
What is the popular "20/4/10 rule" for auto loan affordability?↓
Financial advisors recommend putting at least 20% down, financing for no longer than 4 years (48 months), and keeping total monthly automotive expenses (loan payment, insurance, fuel, maintenance) under 10% of gross monthly income.
How does extending my loan term to 72 or 84 months impact affordability?↓
Extending loan tenure lowers monthly payments, artificially allowing you to purchase a pricier car. However, it substantially escalates total interest paid and puts you at severe risk of "negative equity" (owing more than the car is worth).
Does trade-in credit provide sales tax savings?↓
Yes, in most US states, sales tax is calculated only on the net difference between the purchase price and trade-in allowance, effectively reducing total tax outlay.
What additional ongoing ownership expenses should I budget for besides the loan payment?↓
Auto insurance, fuel or charging, routine servicing, replacement tires, and annual state registration fees typically add another $200 to $400 per month on top of the car loan payment.
What limitation should I anticipate regarding dealer documentation fees?↓
Dealer documentation (doc) fees vary dramatically by state. Some states cap doc fees at $75–$150, while states without fee caps can feature dealer doc fees exceeding $800 to $1,000.
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Open calculator →Source Citation & Disclaimer
Informational tool only; not licensed tax, legal, or financial advice.