Lenders and personal budgets don't always agree on how much house is "affordable" — being approved for a certain mortgage amount is not the same as being comfortable paying it every month.
The lender's math: the 28/36 rule
Most conventional lenders use a version of the 28/36 rule as a guideline: your total housing costs (principal, interest, taxes, insurance) shouldn't exceed roughly 28% of gross monthly income, and your total debt payments (housing plus all other debt) shouldn't exceed roughly 36%. Some programs allow higher ratios — up to 43-50% total debt-to-income for well-qualified borrowers — but higher ratios generally mean less financial breathing room.
Why "approved for" isn't "comfortable at"
Lenders calculate affordability based on gross income and existing debt, but they don't know your other expenses — childcare, healthcare costs, how much you want to save, or your risk tolerance for income disruption. Two households approved for the exact same mortgage amount can have very different actual financial comfort at that payment level.
The full cost of homeownership
The mortgage payment itself is only part of the real monthly cost. Property tax, homeowners insurance, and (if your down payment is under 20%) private mortgage insurance (PMI) all add to the required payment beyond principal and interest. Maintenance and repairs — often estimated at 1-2% of home value annually — aren't part of any mortgage calculation but are a real ongoing cost.
A practical approach
Start with your current comfortable spending, not your maximum approved amount. Calculate what a given price and rate combination actually costs monthly with the Mortgage Calculator, then check that figure against your real budget — including savings goals and other financial priorities — rather than just the maximum a lender is willing to approve.
Check your DTI before house-hunting
Since debt-to-income ratio is central to what you'll qualify for, checking your own DTI before shopping gives a realistic sense of your range. Use the Debt-to-Income Calculator to see where you currently stand, including how a new mortgage payment would change that ratio.