What Is the Car Payment Affordability Calculator?
This calculator works backward from your monthly budget to tell you the maximum car price you can afford. Instead of starting with a sticker price, you enter how much you can comfortably pay each month, your down payment, the loan's annual interest rate (APR), and the term in months. It then computes the largest loan you can support and adds your down payment to reveal the total vehicle price within reach.
How to Use It
Enter your monthly payment budget, the cash you plan to put down, the APR your lender quotes, and the loan term in months. The result shows the maximum car price, the financed loan amount, and the total interest you would pay over the life of the loan. Adjust the inputs to see how a larger down payment or shorter term changes what you can afford.
The Formula Explained
The financed loan amount is the present value of an annuity:
$$\text{loan} = M \cdot \frac{1 - (1+r)^{-n}}{r}$$where M is the monthly payment, r is the monthly interest rate (\(\text{APR} \div 12 \div 100\)), and n is the number of months. The maximum car price is that loan amount plus your down payment. Total interest equals total payments (\(M \times n\)) minus the financed loan amount.
Worked Example
With a $400 monthly budget, $3,000 down, 6% APR, and a 60-month term: \(r = 0.005\), \(n = 60\). The financed loan \(\approx \$20{,}690.22\), so the maximum car price \(\approx \$23{,}690.22\). Total payments \(= \$400 \times 60 = \$24{,}000\), so total interest \(\approx \$24{,}000 - \$20{,}690.22 = \$3{,}309.78\).
FAQ
Does this include taxes and fees? No — the result is the vehicle price your loan and down payment can cover. Budget extra for sales tax, registration, and dealer fees.
What if my APR is 0%? With a promotional 0% rate, the loan amount is simply your monthly payment times the number of months.
Should I spend my entire budget? Leave room for insurance, fuel, and maintenance. Many advisors suggest keeping total car costs under 15–20% of take-home pay.
