Determining Exactly How Much House You Can Truly Afford
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Review boardFiguring out how much house you can afford is the most important step before you start browsing Zillow or attending open houses. Lenders look at specific mathematical ratios to determine your borrowing limit, but what the bank says you can afford and what your budget can actually handle are often two different numbers.
The 28/36 Rule of Thumb
The golden rule of home affordability is the 28/36 Rule. Most traditional lenders and financial advisors recommend staying within these boundaries to avoid becoming "house poor."
The Front-End Ratio (28%)
Your total housing costs should not exceed 28% of your gross monthly income (your income before taxes are taken out). Housing costs include:
- Mortgage principal and interest
- Property taxes
- Homeowners insurance
- HOA fees (if applicable)
- Private Mortgage Insurance (PMI)
The Back-End Ratio (36%)
Your total debt payments should not exceed 36% of your gross monthly income. This is also known as your Debt-to-Income (DTI) ratio. This includes the housing costs mentioned above, plus:
- Auto loan payments
- Student loan payments
- Minimum credit card payments
- Personal loan payments
Example Calculation
If your household earns $120,000 per year, your gross monthly income is $10,000. Under the 28/36 rule:
- Max Housing Cost (28%): $2,800 per month
- Max Total Debt (36%): $3,600 per month
If you already pay $1,000/month for a car and student loans, your total debt is already at 10%. This means you only have 26% left for housing, lowering your maximum affordable mortgage payment to $2,600.
How Your Down Payment Affects Affordability
Your down payment dictates two critical aspects of affordability: your loan amount and your PMI requirements.
While a 20% down payment is the gold standard because it eliminates Private Mortgage Insurance (PMI), many first-time homebuyers purchase with 3% to 5% down using conventional loans, or 3.5% using FHA loans. Just remember that a smaller down payment increases your monthly mortgage payment and adds PMI costs, which directly cuts into your 28% maximum housing budget.
Don't Forget the Hidden Costs
When calculating affordability, many buyers only look at the Zillow "Estimated Payment." But homeownership comes with hidden carrying costs that renters don't face:
- Closing Costs: Usually 2% to 5% of the total loan amount, paid upfront.
- Maintenance and Repairs: Budget 1% to 2% of the home's value per year. For a $400,000 home, that's $4,000 to $8,000 annually.
- Utilities: Houses generally cost significantly more to heat, cool, and light than apartments.
Next Steps: Crunching Your Own Numbers
Now that you understand the mechanics of the 28/36 rule and DTI, you should run your exact income and debts through a calculator to get a precise number.
Use our Home Affordability Calculator →
Use our Standard Mortgage Calculator →