How Much Home Can I Actually Afford?
Key Findings
The 28/36 Rule and Why It’s Incomplete
The most cited affordability rule says housing costs should stay below 28% of gross income (front-end ratio) and total debt payments below 36% (back-end ratio). On $100K gross income, that’s $2,333/mo for housing. At 6.1% with 20% down, that supports roughly a $350K–$380K home. But this rule was designed for underwriting, not financial optimization. It tells you what the bank will approve—not what you can comfortably sustain while still investing, building an emergency fund, and living your life.
What Lenders Actually Approve
FHA allows up to 43% back-end DTI (and sometimes 50% with compensating factors). Conventional loans cap at 45–50% DTI. At $100K income with no other debts, an aggressive lender might approve $500K+—roughly 35% above what the 28/36 rule suggests. Getting approved for a mortgage and being able to afford the home are very different things. The gap between lender-approved and financially sustainable is where most first-time buyers make expensive mistakes.
The True Monthly Cost
A $450K home at 20% down and 6.1% generates roughly $2,840/mo in PITI (principal, interest, taxes at 1.2%, insurance at $150/mo). But actual monthly carrying cost includes maintenance ($375–$750/mo at 1–2%), potential HOA ($200–$600/mo), utilities above rental baseline ($100–$250/mo), and opportunity cost on the down payment (~$525/mo on $90K at 7%). Total true cost: $3,500–$4,600/mo. The listing price is the beginning of the conversation.
The Reverse Budget Method
Instead of asking ‘how much home can I afford?’ start with ‘how much do I need for everything else?’ Take your net monthly income, subtract: retirement contributions (15%+), emergency fund (until you have 6 months), insurance, food, transportation, debt minimums, and discretionary spending. What remains is your true housing budget. For many households, this number is 20–40% below what a lender approves. It’s also the number that lets you sleep at night.
Income Multiples by Market
The traditional guideline of 3–4x annual income produces different outcomes depending on where you live. In Phoenix ($455K median, $113K needed at 4x), the math works for dual-income tech households. In San Francisco ($1.2M median, $300K needed at 4x), it excludes roughly 85% of households. In Houston ($335K median, $84K needed at 4x), it’s accessible to most professional couples. National data shows first-time buyers are averaging 4.2x income—above the traditional comfort zone—because entry prices have outpaced wage growth in most metros since 2020.
How DwellQ Approaches Affordability
DwellQ doesn’t tell you what you can afford—it shows you the net worth outcome of buying at a specific price point vs. renting. This is more useful than an affordability calculator because it quantifies the financial tradeoff. If buying a $500K home produces lower net worth than renting for 8 years, it doesn’t matter that you ‘qualify’—the math says wait, save more, or look at a lower price point. Run your actual numbers and see where the crossover falls.
Frequently Asked Questions
- Consumer Financial Protection Bureau. Debt-to-Income Ratio Guidelines.[consumerfinance.gov]
- Federal Housing Administration. FHA Loan Limits and DTI Requirements.[hud.gov]
- Fannie Mae. Desktop Underwriter Eligibility Matrix: DTI Ratios.[fanniemae.com]
- National Association of Realtors. Profile of Home Buyers and Sellers, 2024.[nar.realtor]
- Joint Center for Housing Studies, Harvard. The State of the Nation’s Housing, 2024.[jchs.harvard.edu]
- Federal Reserve Bank of St. Louis. FRED: Median Household Income and Home Price Index.[fred.stlouisfed.org]
- Bureau of Labor Statistics. Consumer Expenditure Survey: Housing Costs.[bls.gov]
- Mian, A. and Sufi, A. ‘House Prices, Home Equity-Based Borrowing, and the US Household Leverage Crisis.’ AER, 101(5), 2011.