The bank will tell you how much they're willing to lend you. That number is almost always higher than how much you should actually borrow. Understanding the difference could save you years of financial stress — or free up thousands of dollars a month you'd otherwise be sending to a mortgage servicer.
Why Lender Pre-Approval Isn't the Same as "Affordable"
Lenders use your gross income, debts, and credit score to calculate the maximum loan they'll offer. Their job is to make loans. Your job is to protect your lifestyle, your emergency fund, your retirement contributions, and your ability to handle life's surprises. These are not the same objective.
Getting pre-approved for $600,000 doesn't mean a $600,000 home fits your budget. It means the lender believes you can make the payments — at least at the start.
The Two Rules Lenders Use (And Their Limits)
The 28% Front-End Rule
Lenders typically want your total monthly housing cost (principal, interest, taxes, insurance — PITI) to be no more than 28% of your gross monthly income.
Example: If your gross household income is $8,000/month, the 28% rule says your housing payment should be ≤ $2,240/month.
The 36% Back-End Rule (Debt-to-Income)
Your total monthly debt payments — housing plus car loans, student loans, credit cards — should be ≤ 36% of gross income. Some lenders allow up to 43–45% for conventional loans, and even higher for FHA loans. But just because they allow it doesn't mean it's wise.
Example: Same $8,000/month income. 36% = $2,880 total debt payments. If you have a $500 car payment and $300 in student loans, you have $2,080 left for housing.
Why These Rules Can Mislead You
Both rules use gross income — before taxes. After a 25% effective tax rate, that $8,000 gross is $6,000 in take-home pay. Your 28% housing payment ($2,240) is suddenly 37% of what actually hits your bank account. Add groceries, childcare, utilities, and retirement savings and it gets tight fast.
A more conservative rule: keep total housing under 25% of your net (take-home) pay.
A Better Way to Calculate Your Number
Work backwards from what you can realistically spend, not forward from what a lender offers.
Step 1: Find Your True Monthly Budget
Add up your current monthly non-housing expenses:
- Food and groceries
- Transportation (car payment, insurance, gas)
- Utilities (currently — homeownership utilities often run higher)
- Health insurance and out-of-pocket medical
- Childcare or school expenses
- Student loans and other debt payments
- Subscriptions, entertainment, dining out
- Retirement contributions (don't cut these)
- Emergency fund savings (target 3–6 months of expenses)
Subtract that total from your net monthly income. The remainder is your maximum housing budget — but leave a buffer. Life is not a spreadsheet.
Step 2: Convert Your Payment Budget to a Loan Amount
Use our free mortgage calculator in reverse: enter different home prices and find the one where the total monthly payment (including taxes and insurance) hits your budget number.
Don't forget: your monthly payment includes more than principal and interest. Budget for:
- Property taxes: typically 1–1.5% of home value per year
- Homeowners insurance: roughly $1,000–2,000/year on average
- PMI (if less than 20% down): 0.5–1.5% of the loan per year
- HOA fees (if applicable): varies widely, $0–$1,000+/month
For a complete view of what you'll actually pay, read our guide on the true cost of homeownership beyond your monthly payment.
Step 3: Factor in the Down Payment and Closing Costs
Closing costs typically run 2–5% of the purchase price on top of your down payment. On a $400,000 home, that's $8,000–$20,000 in cash needed at closing, separate from your down payment.
If you're putting 5% down ($20,000), you need $28,000–$40,000 in cash ready to go — plus you want to preserve your emergency fund afterward. Run this math early so you're not scrambling at closing.
The Affordability Gap: What the Numbers Don't Capture
Affordability isn't just a math problem. It's also about life stability. Before committing to a mortgage, honestly answer these questions:
- Job security: How stable is your income? Would one layoff make the payment unmanageable?
- Two-income dependency: If you're buying on two incomes, can you cover the mortgage on one if needed?
- Maintenance buffer: Homes require ongoing repair. Budget 1–2% of home value per year. A $400,000 home = $4,000–$8,000/year in maintenance costs on average.
- Plans to stay: If you sell in 2–3 years, transaction costs (5–6% agent commission + closing costs) can easily wipe out any equity gain. Homeownership generally makes more financial sense when you stay at least 5–7 years.
Price-to-Income Ratios: A Quick Sanity Check
A simple rule of thumb: home price should be no more than 3–4x your annual gross household income. At 7% interest, a home at 4x income will be right at or above the 28% front-end limit. At 5–6x income, the monthly payments will strain most budgets.
| Household Income | Conservative (3x) | Moderate (4x) | Stretching (5x) |
|---|---|---|---|
| $60,000 | $180,000 | $240,000 | $300,000 |
| $80,000 | $240,000 | $320,000 | $400,000 |
| $100,000 | $300,000 | $400,000 | $500,000 |
| $120,000 | $360,000 | $480,000 | $600,000 |
| $150,000 | $450,000 | $600,000 | $750,000 |
These are rough guides at current rates — the actual monthly payment also depends heavily on your interest rate. Understanding whether to choose a fixed or adjustable rate mortgage can meaningfully change what you qualify for and what your payment looks like over time.
How to Increase Your Buying Power
If the numbers aren't working out for the home you want, you have several levers:
- Save a larger down payment. More down = smaller loan = lower payment. It also eliminates PMI at 20%.
- Pay down existing debt. Reducing car loans and credit card balances improves your debt-to-income ratio, which can get you a better rate and higher approval amount.
- Improve your credit score. The difference between a 680 and 760 credit score can be 0.5–1% on your rate, which translates to tens of thousands of dollars over the loan life.
- Shop for a lower rate. Getting quotes from 3–5 lenders is one of the most impactful things you can do. Small rate differences compound enormously. Learn more about how mortgage interest is calculated to understand why rate shopping matters so much.
- Look at different loan structures. A 15-year loan has a lower interest rate but higher payment. An ARM might offer a lower initial rate. Each option has trade-offs — learn them in our guide on using a mortgage calculator to compare loan options.
The Bottom Line
The right amount of house is the amount that keeps your finances strong even when things go wrong — a job loss, a medical bill, a roof replacement. A lender approval is not a budget. Your budget is your budget.
Start with our free mortgage calculator to find the monthly payment range that works for your real take-home pay, then work backwards to the purchase price that fits. That's how you buy a home you can comfortably keep.