What's the honest starting point?
Start from a monthly payment you'd be comfortable living with, not from a purchase price. Price is what you negotiate; the payment is what you live with for years.
Working payment-first inverts the usual house-hunt and protects you from the classic first-timer trap: falling for a price tag, then discovering what taxes, insurance, and mortgage insurance do to it. Play with the inputs in my affordability calculator, it's built for exactly this, and treat its output the way this page treats every number: an estimate to plan around, pending your real file.
What is the 28/36 guideline?
Housing costs near 28% of gross monthly income, total debt payments near 36%: the classic budgeting guardrail, echoed in CFPB's affordability guidance.
Illustration with round numbers (an example, not an offer or your scenario): on a $6,000 gross monthly income, 28% puts the housing budget near $1,680 a month, and 36% caps all debt payments, housing plus cars, cards, and student loans, near $2,160. Notice what the example doesn't contain: a rate, a loan amount, or a promise. It's a budget frame. Underwriting uses different, program-specific math, and your comfortable number might sit below both.
What does a monthly payment actually include?
PITI: principal, interest, property taxes, and homeowners insurance, plus mortgage insurance on most low-down loans and HOA dues where they exist.
The two parts first-time buyers underestimate are taxes and insurance, which vary enormously by state and property: the same purchase price can carry payments hundreds of dollars apart in different counties. Mortgage insurance depends on the loan type, the program comparison covers how, and on some loans it's the third-biggest line. Budgeting on principal-and-interest alone is how "affordable" houses surprise their owners.
What do lenders actually use?
Debt-to-income ratios: your monthly debt payments divided by gross monthly income, measured against each program's own limits, alongside credit, assets, and the property.
Program DTI math is more generous than the 28/36 guideline more often than not, which is exactly why the guideline exists: it protects your budget where underwriting only protects the lender. The program-level DTI rules belong to the loan guides, and your actual numbers come from a pre-approval, which replaces every estimate on this page with your file's real answer.
Approved-for vs comfortable-with: which number wins?
Comfortable wins, every time someone asks me honestly. Underwriting measures repayment risk; it has no opinion about your daycare costs, travel, savings rate, or sleep.
The gap between the approval ceiling and the comfortable payment can be substantial, and spending to the ceiling is the most common regret I hear from buyers a year in. My practice is to show you both numbers and recommend shopping from the comfortable one, with the ceiling held in reserve for the right house rather than spent on the first one. A mortgage you barely notice is the goal; a mortgage you can technically afford is just a stress subscription.