There are two very different answers to this question. There's what a lender will approve, and there's what will feel comfortable at month twelve of ownership. Great buyers understand both — and buy inside the smaller of the two.
The approval side is mostly math: your debt-to-income ratio (DTI). Most conventional programs allow up to 45–50% DTI, meaning total monthly debt payments (including your new mortgage) can't exceed roughly half your gross monthly income. That's the ceiling, not the target.
The comfort side is different. Start with net income, not gross. Subtract retirement contributions, health insurance, and taxes you haven't yet paid. What's left is what actually funds your life. A mortgage payment north of 35% of net income tends to feel tight; under 28% tends to feel comfortable.
In Texas, don't forget property taxes. A $500,000 home in a 2.2% county carries roughly $917/month in property tax alone — before principal, interest, or insurance. Some suburbs approach 3%. Run the real number, not the base loan payment.
The best exercise: use our calculator with your target price, real Texas taxes, and current rates. If the total monthly is under 30% of your net income and still leaves room for savings, that's your comfortable ceiling. Shop below it, not at it.