Before house-hunting, it helps to know your number — the maximum home price that fits comfortably in your budget. Lenders use formulas to determine how much they'll let you borrow, but those limits aren't always the same as what's comfortable for your lifestyle and goals.
The 28/36 rule
Most conventional lenders use two ratios to assess affordability. The front-end ratio caps your housing costs (mortgage principal & interest, property taxes, insurance, and PMI) at 28% of your gross monthly income. The back-end ratio caps all your monthly debt payments — housing plus car loans, student loans, credit cards, etc. — at 36% of gross monthly income. The lower of the two limits determines your maximum housing payment, and therefore your maximum home price.
Why your other debts matter so much
Two buyers with identical incomes can qualify for very different home prices depending on their existing debt. A buyer with $800/month in car and student loan payments has much less room under the 36% cap than a buyer with no other debt — even though both have the same 28% housing cap. Paying down debt before applying can meaningfully increase your buying power.
Down payment trade-offs
A larger down payment reduces your loan amount (lowering your monthly payment), can eliminate PMI if it gets you to 20% equity, and may qualify you for a better interest rate.
But it's not always the right move to put down everything you have. Keeping an emergency fund and money for moving costs, furniture, and repairs is important — a home with no cash cushion left over can create financial stress even if the mortgage itself is affordable.
The hidden costs of homeownership
Your mortgage payment isn't the whole picture. Budget for property taxes and homeowners insurance (included in most calculators), HOA fees if applicable, ongoing maintenance (a common rule of thumb is 1–2% of the home's value per year), utilities — which are often higher for larger homes — and closing costs when you buy (typically 2–5% of the purchase price).
Affordable on paper vs. affordable for you
Lenders will often approve you for more than you may want to spend. Just because you qualify for a $450,000 home doesn't mean that payment leaves room for saving, travel, or unexpected expenses. Consider running your numbers at a payment level below your maximum approval to build in a comfort margin.
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Frequently Asked Questions
Is the 28/36 rule a hard limit?+
No — it's a guideline most lenders use as a starting point, but actual approval depends on credit score, down payment, loan type, and overall financial profile. Some loan programs allow back-end ratios as high as 43–50% with compensating factors like a high credit score or large reserves.
Should I buy at the top of my approved amount?+
Not necessarily. Lenders approve based on what you can technically afford to pay, not what fits your lifestyle and goals. Many financial planners suggest keeping housing costs comfortably below the 28% cap to leave room for saving and unexpected expenses.
How much should I save for closing costs and moving expenses?+
Plan for 2–5% of the home's purchase price in closing costs, plus a separate cushion of a few thousand dollars for moving, immediate repairs, and furnishing. These costs are in addition to your down payment.