How Much House Can I Afford? A Simple Rule-Based Guide

Before you fall in love with a listing, it helps to know roughly what price range actually fits your budget. Lenders and financial planners lean on a handful of simple rules of thumb to answer this — none of them perfect, but together they give a realistic starting range before you talk to a lender. This guide walks through the two most commonly used rules, a full worked example, the other costs that affect the final number, and how your down payment and interest rate change what you can actually afford.

The 28/36 rule

This is the rule most mortgage lenders actually use when qualifying you for a loan:

• 28% rule: your monthly housing costs (mortgage principal + interest + property tax + insurance, often called PITI) shouldn't exceed 28% of your gross (pre-tax) monthly income.
• 36% rule: your total monthly debt payments — housing plus car loans, student loans, credit cards, and other debt — shouldn't exceed 36% of gross monthly income.

Lenders call this your debt-to-income ratio (DTI), and it's one of the biggest factors in what loan amount you'll actually qualify for. Some loan programs allow a higher DTI than 36% — certain conventional and government-backed loans permit ratios up to 43-50% under specific conditions — but 28/36 remains the traditional benchmark for what's considered comfortably affordable rather than merely approvable.

The 3–5x income rule

A rougher, older rule of thumb: your total home price shouldn't exceed roughly 3 to 5 times your gross annual household income, depending on your down payment, interest rates, and other debt. It's less precise than the 28/36 rule but useful as a quick sanity check — if you earn $80,000 a year, this rule suggests a home price somewhere between $240,000 and $400,000, a wide range that narrows considerably once you factor in your actual down payment and current interest rates.

This rule was more reliable when interest rates stayed within a narrower historical band. Because monthly payment size depends heavily on the interest rate at the time you borrow, the same income-multiple can translate to very different actual monthly payments depending on where rates sit — which is why the 28/36 rule, tied directly to your actual monthly payment rather than a multiple of income, tends to be the more dependable of the two.

A worked example

Say your household earns $90,000 a year, or $7,500 a month, before taxes.

• 28% rule: $7,500 × 0.28 = $2,100 max monthly housing payment (PITI).
• 36% rule: $7,500 × 0.36 = $2,700 max total monthly debt, including that housing payment.

If you already pay $400/month toward a car loan and student loan, that leaves $2,700 − $400 = $2,300 for housing under the 36% rule — but the 28% rule still caps you at $2,100, so $2,100 is your binding limit. From there, a mortgage calculator can translate that monthly payment cap into an approximate home price, once you factor in your down payment, interest rate, property tax rate, and insurance estimate.

Using a 20% down payment, a 30-year term, and a representative interest rate, a $2,100 monthly PITI budget (after setting aside roughly $300–350 for estimated property tax and insurance, leaving about $1,750–1,800 for principal and interest) typically supports financing in the rough neighborhood of $300,000–330,000, which combined with the 20% down payment puts the total affordable home price in the ballpark of $375,000–410,000. The exact number shifts meaningfully with the interest rate available to you, so this range is a starting point for a real mortgage calculation, not a substitute for one.

Other factors that matter

• Down payment size — a larger down payment lowers your loan amount and monthly payment, and can help you avoid private mortgage insurance (PMI) below 20% down.
• Interest rate — even a 1-point difference in rate meaningfully changes what monthly payment a given loan amount produces.
• Credit score — directly affects the interest rate you're offered, and therefore your affordable price range.
• Property tax and insurance rates — vary significantly by location and are easy to underestimate.

How down payment size changes the math

The down payment does more than just reduce your loan amount — it changes several things at once. Below 20% down on a conventional loan, lenders typically require private mortgage insurance (PMI), an added monthly cost (often roughly 0.5–1.5% of the loan amount annually) that protects the lender, not you, and that generally disappears once you've built enough equity. A larger down payment also often qualifies you for a somewhat better interest rate, since it represents a smaller loan relative to the home's value and therefore less risk to the lender.

That's why comparing two buyers with the same income can produce very different affordable price ranges: one with a 20% down payment avoids PMI and may access a better rate, stretching their affordable price higher, while one with a 5% down payment carries PMI and possibly a higher rate, which eats into the housing budget even at the same target monthly payment.

What lenders look at beyond the ratios

The 28/36 rule is a useful planning tool, but actual mortgage approval depends on a fuller underwriting picture: your credit score and credit history, employment stability and income verification, cash reserves after closing, and the specific loan program you're applying for (conventional, FHA, VA, and other programs each have their own DTI limits and down payment requirements). Two households with identical income and debt can qualify for different amounts based on these other factors, which is why the numbers above are a realistic planning range rather than a guaranteed pre-approval figure.

Renting vs. buying at your price range

Affordability calculations often stop at "what can I qualify for," but it's worth separately asking "what should I actually spend." Housing costs that sit right at the edge of the 28/36 limits leave little room for savings, emergencies, or lifestyle flexibility. Many financial planners suggest treating the 28/36 rule as a hard ceiling rather than a target — aiming somewhat below it, particularly in markets with high property taxes or homeowners insurance costs, or if your income has any variability (commission, self-employment, bonus-heavy compensation).

The true cost of homeownership beyond the mortgage payment

The 28/36 rule focuses on PITI (principal, interest, property tax, and insurance), but that's not the full cost of owning a home. A realistic affordability picture also accounts for: maintenance and repairs — a commonly cited rule of thumb budgets 1–2% of the home's value annually for upkeep, meaning a $400,000 home might reasonably need $4,000–8,000 a year set aside; HOA fees, if applicable, which can range from under $50 to several hundred dollars a month depending on the property and amenities; utilities, which are often higher for a house than a comparably sized rental, especially with an older heating or cooling system; and closing costs at purchase, typically 2–5% of the loan amount, covering lender fees, title insurance, appraisal, and other one-time costs due at signing, separate from the down payment itself.

None of these show up in a standard mortgage calculator's monthly payment estimate, but skipping them in your planning is one of the most common ways buyers end up "house poor" — technically able to make the mortgage payment, but with little room left for anything else once the full cost of ownership is accounted for.

Regional differences that shift the math

The same income and the same 28/36 calculation can lead to very different actual home-buying experiences depending on location. Property tax rates alone vary enormously — some states average under 0.5% of home value annually, while others average well above 2%, which on a $400,000 home is the difference between roughly $2,000 and $8,000 a year, a gap that meaningfully changes how much loan amount fits within a given PITI budget. Homeowners insurance costs vary just as widely based on regional risk factors like flood, wildfire, or hurricane exposure. This is part of why the "3–5x income" rule of thumb breaks down across different markets: the same income multiple buys a very different level of house — and a very different total cost of ownership — in a low-tax, low-insurance-risk area versus a high-tax, high-risk one.

Common affordability-estimating mistakes

• Using pre-approval amount as a spending target. A lender's maximum pre-approval reflects what you qualify for under their underwriting rules, not necessarily what's comfortable for your actual budget and goals — the two numbers are often meaningfully different.
• Ignoring how a variable-rate loan could change payments. An adjustable-rate mortgage can offer a lower initial payment, but affordability calculations based on the introductory rate can understate the real long-term cost once the rate adjusts.
• Forgetting to budget for the immediate post-purchase costs — appliances, furniture, and repairs that often come up in the first year of owning a new home, on top of the closing costs already paid at signing.
• Anchoring too heavily on monthly payment alone without considering total interest paid over the life of the loan, which can differ substantially between a 15-year and 30-year term even at a similar monthly payment level once a larger down payment is factored in.

Why pre-approval matters before you start house hunting

A mortgage pre-qualification is a quick, informal estimate based on self-reported income and debt, usually without a credit check — useful for a rough early sense of your range, but not something a seller will treat as a serious offer signal. A pre-approval is a more formal process where a lender verifies your income, assets, and credit, and issues a conditional commitment for a specific loan amount. In competitive housing markets, sellers frequently expect a pre-approval letter (not just pre-qualification) before taking an offer seriously, since it demonstrates you've actually been vetted by a lender rather than just estimated your own budget.

Getting pre-approved before house hunting also has a practical benefit beyond credibility with sellers: it surfaces your real, lender-verified number — which sometimes differs meaningfully from a DIY 28/36 calculation, in either direction, once your specific credit profile, debt details, and the lender's own guidelines are factored in — before you've emotionally attached to homes outside that range.

This article is for general educational purposes and isn't financial advice. Actual affordability depends on your full financial picture and lender's specific underwriting criteria — consider speaking with a qualified mortgage professional.