You typed your income into a mortgage calculator, it gave you a number, and the number felt great.
Then someone quoted you a real payment on a real house, and it was several hundred dollars higher. The calculator wasn't broken. It just answered a different question than the one you were asking.
What the calculator gave you
Almost every free calculator returns principal and interest. That's the loan. It is genuinely useful and it is not your payment.
Your actual monthly cost is principal and interest, plus property taxes, plus homeowners insurance, plus mortgage insurance if your down payment calls for it, plus HOA dues, plus any MUD or PID obligations attached to the property. In Texas, the stuff after "plus" is not a rounding error. It is frequently the difference between a house you can afford and one you can't.
Texas has no state income tax and leans on property tax instead, and it is one of the more expensive states to insure a home in — hail is a real actuarial category here. Both land in your monthly payment.
The four things that actually set your number
Your income — but the version underwriting recognizes
Not what you earn. What can be documented and averaged in a way that satisfies a lender. For a salaried W-2 employee those are usually the same number. For anyone self-employed, commissioned, or newly bonused, they can be very different — and if that's you, this is the article you want.
Your existing monthly debts
Car payments, student loans, credit card minimums, child support. Underwriting compares your total monthly obligations to your gross income, and every existing payment displaces mortgage you could otherwise qualify for. Paying off a car before you buy sometimes moves your number more than saving another few thousand dollars does.
Your down payment
It changes three things at once: the loan size, whether mortgage insurance applies, and how a lender prices your risk. Larger is not automatically better — money that goes into the house is money that isn't in your account the day after closing, and reserves matter more than most buyers expect.
The property itself
This is the one that gets skipped, and in DFW it's decisive. Two homes at the same price in different tax districts carry different monthly costs, permanently. A one-point difference in the combined tax rate on a $500,000 home is roughly $417 a month. Add a MUD or PID and it moves again.
Which is why an affordability number that isn't tied to an actual address is a rough draft. Here's how the district math works.
Rates move your number more than you think
I'm not going to quote you a rate — anything I printed here would be wrong by the time you read it, and a number on a webpage isn't your rate anyway.
What's worth internalizing is the shape of it: rate movements that sound trivial change your buying power by tens of thousands of dollars, and they do it quietly. This cuts both ways. It is why a pre-approval from four months ago is a historical document, and it is why "waiting for rates" is a strategy with a cost that nobody puts on the page.
The right response isn't to guess. It's to know your number under current conditions and re-check it when conditions change.
Find your real number in three steps
- Start with the payment, not the price. Decide what you're comfortable sending out every month. That's the constraint that actually binds.
- Work backward with real property data. Take the payment, subtract a realistic tax and insurance estimate for the specific area you're shopping, and what's left is what can service a loan.
- Leave room after closing. A home that empties your accounts on closing day is affordable on paper and stressful in practice. Water heaters break.
Our affordability calculator will get you a working estimate, and it's honest about being an estimate.
One more thing about the 20% myth
You don't need 20% down. Conventional financing starts at 3% for many first-time buyers, FHA at 3.5%, and eligible VA and USDA borrowers can put nothing down at all. The 2026 conforming limit is $832,750 for a one-unit home, and the FHA limit across Dallas, Collin, Denton and Tarrant counties is $563,500.
Twenty percent avoids mortgage insurance. That's the whole benefit. It is a real benefit and it is not a requirement, and treating it as one has kept a lot of people renting for years longer than they needed to.
Want the real number for your situation instead of a range? That conversation is free and takes about fifteen minutes.