Car Affordability Calculator
Calculate the maximum car price you can afford based on your income, existing expenses, insurance costs, and loan terms. Use this before visiting a dealership to set a firm budget grounded in your actual cash flow.
Last updated: September 2026
Formula below · 2 sources (CFPB, Wikipedia) · Updated Sep 2026
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About this calculator
This calculator determines the maximum affordable car price by first setting a safe monthly car payment. The payment is the smaller of two limits: (1) the 20/4/10 guideline that total car costs (payment plus insurance) stay within 10% of gross monthly income, i.e. 10% of income − insurance; and (2) 80% of your monthly surplus (income − fixed expenses − insurance), so the payment never eats all your spare cash. That payment is then converted into a maximum loan amount using the present value of an annuity: Loan = PMT × [1 − (1 + r)^−n] / r, where r is the monthly interest rate and n is the loan term in months. Finally, your down payment is added: MaxCarPrice = downPayment + Loan. The 10% cap is usually the binding limit; fuel and maintenance still come on top, so treat the result as a ceiling.
How to use
Assume monthly gross income $6,000, monthly fixed expenses $3,000, monthly insurance $150, $3,000 down payment, a 5-year (60-month) loan and a 7% interest rate. Limit 1 (10% of income): $6,000 × 0.10 − $150 = $450. Limit 2 (80% of surplus): ($6,000 − $3,000 − $150) × 0.80 = $2,280. The safe payment is the smaller, $450. Monthly rate r = 0.07/12 ≈ 0.005833. Loan = $450 × [1 − (1.005833)^−60] / 0.005833 = $450 × 50.50 ≈ $22,726. MaxCarPrice = $3,000 + $22,726 ≈ $25,726.
Frequently asked questions
What percentage of monthly income should I spend on a car payment?
A widely recommended guideline is to keep your total car expenses — including loan payment, insurance, fuel, and maintenance — under 15–20% of your monthly take-home pay. The car payment alone should ideally stay below 10–15% of net income. For example, on a $5,000/month take-home salary, your loan payment should be no more than $500–$750. Going above 20% total for transportation significantly strains your budget and leaves little room for savings or unexpected expenses. This calculator caps the payment at 10% of gross income minus insurance (the 20/4/10 guideline), or 80% of your monthly surplus if that is lower.
How does the loan term length affect the car I can afford?
A longer loan term (e.g., 72 or 84 months) lowers your monthly payment for the same loan amount, which mathematically allows you to afford a more expensive car. However, longer terms mean you pay significantly more total interest and spend more years underwater (owing more than the car is worth). A 60-month loan is generally considered the maximum advisable term for a new car; 48 months or less is better for used vehicles. Choosing the shortest loan term you can comfortably afford saves thousands in interest and builds equity in the vehicle faster.
Should I include insurance costs in my car affordability calculation?
Yes — insurance is a significant and unavoidable monthly expense that must be factored into affordability before you commit to a purchase price. Full coverage insurance on a new car can range from $100 to $300+ per month depending on your age, driving record, location, and the specific vehicle. Sports cars, luxury vehicles, and EVs often carry higher insurance premiums. By including insurance in this calculator, you avoid the common mistake of buying a car that fits your loan budget but leaves you cash-strapped once real-world monthly costs are added up. Always get insurance quotes for your target vehicle before finalizing your purchase decision.