Car Affordability Calculator
Calculate the maximum car price you can afford based on your monthly income, down payment, loan rate, and term. Use this before visiting a dealership to set a firm budget and avoid overborrowing.
About this calculator
This calculator finds the maximum vehicle purchase price by working backward from your budget. The affordable monthly payment is: maxPayment = monthlyIncome × paymentRatio / 100. That payment is then fed into the present-value loan formula to find the maximum loan principal you qualify for: loanPrincipal = maxPayment × [(1 + r)^n − 1] / [r × (1 + r)^n], where r = annual loan rate / 12 / 100 and n = loan term in months. Adding your down payment gives the total affordable car price: maxCarPrice = loanPrincipal + downPayment. Financial advisors commonly recommend keeping total vehicle expenses (payment + insurance + fuel) below 15–20% of take-home income. This calculator focuses on the payment-to-income constraint; keeping paymentRatio at or below 15% is a conservative, widely recommended starting point.
How to use
Say your monthly take-home income is $5,000, you want payments no more than 15% of income, you have $3,000 down, expect a 6% annual loan rate, and plan a 60-month term. maxPayment = 5,000 × 15 / 100 = $750/month. r = 6/100/12 = 0.005. loanPrincipal = 750 × [(1.005)^60 − 1] / [0.005 × (1.005)^60] = 750 × [0.3489 / 0.006744] ≈ 750 × 51.73 ≈ $38,794. Add down payment: $38,794 + $3,000 = $41,794 maximum car price.
Frequently asked questions
What percentage of my monthly income should I spend on a car payment?
The most widely cited guideline is the 15% rule: keep your car payment at or below 15% of your monthly take-home pay. Some sources stretch this to 20%, but that leaves less room for insurance, fuel, and maintenance, which together can easily add another 5–10% of income. If you are also carrying student loans, credit card debt, or saving for a home, erring closer to 10% gives you financial breathing room. The right percentage depends on your total debt load and savings goals, not just the car payment in isolation.
How does loan term length affect how much car I can afford?
A longer loan term (e.g., 72 or 84 months vs. 48 months) lowers your monthly payment, which means the calculator will show a higher affordable car price for the same income. However, longer terms mean you pay significantly more interest over the life of the loan and spend more time "underwater" — owing more than the car is worth. A 60-month term is generally considered the sweet spot between manageable payments and reasonable total interest cost. Extending to 72+ months is often a sign the vehicle is simply unaffordable at your income level.
Should I include my down payment when calculating car affordability?
Yes — the down payment directly reduces the amount you need to borrow, which lowers either your monthly payment or allows you to afford a more expensive vehicle for the same payment. A larger down payment also reduces the risk of negative equity (being upside-down on the loan) and can help you qualify for better interest rates. Aim for at least 10–20% of the vehicle's purchase price as a down payment; on a $30,000 car, that is $3,000–$6,000. If you cannot meet that threshold, consider a less expensive vehicle or waiting until you've saved more.