A Comprehensive Guide to Determining Realistic Housing Affordability

Roe Luo

Roe Luo

Financial Advisor, CFA

November 21, 2025
9 min read

How Much House Can You Really Afford?

Acquiring a home is one of the largest financial undertakings for most people. While a lender might pre-approve you for a certain mortgage amount, that number doesn't always align with what you can comfortably afford without financial strain. This guide outlines the key principles for determining a realistic home budget.

Principle 1: The 28/36 Rule

A widely accepted guideline in personal finance is the 28/36 rule.

  • Front-End Ratio (28%): Your total monthly housing costs—mortgage principal and interest, property taxes, and homeowners insurance (PITI)—should not exceed 28% of your gross monthly income (GMI).
  • Back-End Ratio (36%): Your total monthly debt obligations—including your PITI plus all other recurring debts (car loans, student loans, credit card payments)—should not surpass 36% of your GMI.

While lenders may sometimes allow higher ratios, sticking to these conservative figures promotes greater financial stability.

Principle 2: Account for ALL Homeownership Costs

Your monthly payment is more than just the mortgage. A true affordability calculation includes:

  • Down Payment: Typically 3.5% to 20% of the purchase price. A down payment under 20% usually requires Private Mortgage Insurance (PMI).
  • Closing Costs: Fees for the transaction, typically 2% to 5% of the home's purchase price.
  • Property Taxes: Varies significantly by location.
  • Homeowners Insurance: Required by lenders to cover potential damages.
  • Maintenance & Repairs: Budget 1-2% of the home's value annually for upkeep and unexpected repairs.
  • HOA Fees: If applicable, these mandatory monthly fees can be substantial.

Illustrative Example

Let's consider a household with a gross annual income of $90,000 (or $7,500 GMI).

  • Maximum Recommended PITI (28% rule): $7,500 * 0.28 = $2,100 per month.
  • Maximum Total Debt (36% rule): $7,500 * 0.36 = $2,700 per month.

This household should look for a home where the total monthly PITI is at or below $2,100, assuming their other debts don't push them over the $2,700 total debt threshold. Online mortgage affordability calculators are useful starting points.

Beyond the Ratios: A Lifestyle-Based Approach

A truly affordable housing payment should not prevent you from:

  • Saving for Retirement: Consistently contributing to a 401(k) or IRA.
  • Building an Emergency Fund: Maintaining a healthy cash reserve.
  • Pursuing Other Financial Goals: Saving for travel, education, or other investments.
  • Enjoying Your Life: Having room in your budget for discretionary spending.

Conclusion

The most prudent approach is to determine your home purchase budget based on your own comprehensive financial plan, not just the maximum amount a lender offers. Prioritizing long-term financial security over acquiring the largest possible property is a hallmark of sound financial decision-making.

Disclaimer: These guidelines are for informational purposes. Consult with a qualified financial advisor and mortgage professional to assess your specific situation.

Roe Luo

Roe Luo

Roe Luo is a Chartered Financial Analyst (CFA) and former equity research analyst with over a decade of experience in the finance industry. He specializes in financial modeling, investment analysis, and making complex financial topics accessible to a broad audience. His focus is on promoting inclusive and understandable investment strategies.

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