How Much House Can You Afford? The 28/36 Rule Explained

Buying a home is the largest financial transaction in most people’s lives. Yet, millions of first-time buyers fall into the trap of asking: “How much will the bank lend me?” instead of asking: “How much can I comfortably afford without becoming house-poor?”

Lenders are in the business of selling loans. Their automated underwriting software determines the maximum risk threshold they can legally approve—not whether you will have enough disposable income left to afford family vacations, emergency car repairs, or retirement contributions.

Here is how to calculate your true home affordability using established mortgage guidelines and real cash flow numbers.

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The Gold Standard: The 28/36 Rule

Mortgage underwriters evaluate home affordability using two critical ratios known as the Front-End DTI and Back-End DTI.

1. Front-End Ratio (Housing Costs ≤ 28% of Gross Income)

Your total monthly housing payment (Principal, Interest, Property Taxes, Homeowners Insurance, and HOA fees) should not exceed 28% of your gross monthly income.

2. Back-End Ratio (All Debt Obligations ≤ 36% of Gross Income)

Your total monthly debt obligations—including your housing payment PLUS student loans, auto payments, personal loans, and minimum credit card payments—should not exceed 36% of your gross monthly income.

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Affordability Breakdown by Household Income Tier

The table below illustrates maximum recommended monthly payments and home purchase price estimates under the 28% front-end rule at a 6.5% interest rate with 10% down:

Annual Household Income	Gross Monthly Income	Max Housing Payment (28%)	Estimated Max Home Price
$60,000 / year	$5,000 / mo	$1,400 / mo	$185,000 – $210,000
$85,000 / year	$7,083 / mo	$1,983 / mo	$265,000 – $295,000
$110,000 / year	$9,167 / mo	$2,566 / mo	$345,000 – $385,000
$150,000 / year	$12,500 / mo	$3,500 / mo	$470,000 – $525,000
$200,000 / year	$16,667 / mo	$4,667 / mo	$625,000 – $700,000

Assumptions: 30-year fixed loan at 6.5%, 10% down payment, 1.2% property tax rate, and standard homeowners insurance.

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The Hidden Costs of Homeownership: The 1% Rule

When you rent an apartment, your rent payment is the maximum you will pay for housing that month. If the air conditioner dies or a pipe bursts, the landlord pays.

When you own a home, your mortgage payment is the minimum you will pay.

To avoid financial catastrophe, apply the 1% Maintenance Rule: Budget at least 1% of your home’s purchase price each year for routine maintenance and long-term capital replacements (roof, HVAC, appliances, exterior painting).

• On a $350,000 home, you must budget roughly $3,500/year ($290/month) into a dedicated home maintenance sinking fund.

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How to Test-Drive Your Future Mortgage Before Buying

Before submitting offers on houses, conduct a 3-month Mortgage Stress Test:

1. Calculate the difference between your current rent and your estimated future mortgage payment (including taxes and HOA).
2. If your current rent is $1,600 and your future mortgage will be $2,400, the difference is $800 per month.
3. For the next three months, automatically transfer that exact $800 into a separate savings account on the first day of every month.
4. If living on the remaining cash feels easy and comfortable, you can confidently afford the home. If you feel stressed, you have identified your affordability ceiling before signing a 30-year contract.