HowAffordable’s car baseline sizes the starting payment at 10% of monthly take-home income on a 60-month loan. That is a modeling default, not a law. Many banks still quote payment or DTI caps on gross income. Either way, the payment is only one line.
A labeled hypothetical
Imagine $3,800 take-home, $1,600 rent already in expenses, $280 in other debts, and $900 of remaining bills (food, insurance, phones). Ten percent of $3,800 is a $380 modeled car payment.
Leftover cash is $3,800 − $280 − $1,600 − $900 − $380 = $640. Stretch the car to 15% of take-home ($570) and leftover falls to about $450. The “can I get approved?” question and the “can I still live?” question diverged in two steps.
What else the report card looks at
- Down payment of 20% scores strongest in this app’s car grades, because a thinner down payment usually means a larger loan and more interest.
- Emergency savings of three to six months of expenses is graded separately. A car that fits the payment but zeros the savings account is a weaker overall picture. See the CFPB emergency-fund guide.
- Total DTI still matters to lenders. The CFPB DTI explainer is a better description of that overlay than any car-lot payment quote.
Insurance, fuel, and maintenance are easy to under-count. If you already listed them in expenses, the leftover figure is more honest than payment-to-income alone.
Full scoring bands are on the methodology page. Run the car calculator with your take-home and bills rather than copying this example.