How to Calculate How Much House You Can Afford

Determining how much house you can afford is one of the most critical steps in the home-buying process. The general rule is that your total monthly housing costs should not exceed 28% of your gross monthly income, though lenders may allow up to 43% when accounting for all debt. By understanding the key factors that influence affordability—including your income, down payment, credit score, and debt—you can establish a realistic budget before house hunting.

Understanding the 28/36 Rule

The 28/36 rule is the lending industry’s standard for determining how much house you can afford. Here’s how it works:

The 28% Rule: Your housing expenses (mortgage payment, property taxes, homeowners insurance, and HOA fees) should not exceed 28% of your gross monthly income.

The 36% Rule: Your total debt payments, including housing, car loans, student loans, and credit cards, should not exceed 36% of your gross monthly income.

For example, if you earn $5,000 per month gross income, your housing costs should stay below $1,400 (28%), and your total debt payments should not exceed $1,800 (36%).

While these percentages are guidelines rather than absolute rules, they’ve proven effective for decades. Some lenders offer more flexible terms for borrowers with excellent credit scores and stable income, potentially allowing housing expenses up to 43% of gross income. However, stretching beyond these guidelines increases your financial risk and could make homeownership stressful rather than enjoyable.

Key Factors That Affect Affordability

Several factors work together to determine your actual home-buying budget:

Your Down Payment: The amount of cash you can put down directly impacts your loan amount and monthly payment. A 20% down payment means you avoid private mortgage insurance (PMI), saving thousands over the loan’s life. However, many buyers successfully purchase with 3-5% down, though they’ll pay PMI costs.

Credit Score: Your credit score determines your interest rate. A score of 760+ typically qualifies for the best rates, while scores below 620 may face higher rates or limited lending options. Even a 0.5% difference in interest rate can mean $50,000+ in additional costs over a 30-year mortgage.

Debt-to-Income Ratio (DTI): Lenders examine all your monthly debt obligations relative to income. This includes car payments, student loans, credit card minimums, and child support. A lower DTI ratio improves your chances of approval and better rates.

Interest Rates: Market interest rates fluctuate and significantly impact affordability. When rates rise, your monthly payment increases for the same loan amount. A 1% rate increase on a $300,000 mortgage roughly adds $250 to your monthly payment.

Loan Type: FHA loans require lower down payments (3.5%) but include mortgage insurance. Conventional loans typically require 5-20% down. VA loans offer special benefits for military members. Each has different affordability implications.

Job Stability and Income: Lenders prefer to see 2+ years of stable employment. If you’re self-employed, expect to provide 2 years of tax returns. Income variations affect the maximum loan amount you qualify for.

Calculating Your Budget Step-by-Step

Step 1: Calculate Your Gross Monthly Income

Add all sources of income: salary, bonuses, side hustle income, rental income, and investment returns. Use average annual income divided by 12. Only include income you expect to continue for at least the next 3 years.

Step 2: Apply the 28% Rule

Multiply your gross monthly income by 0.28. This is your maximum monthly housing budget. Example: $5,000 × 0.28 = $1,400 maximum housing payment.

Step 3: Subtract Non-Mortgage Housing Costs

Property taxes, homeowners insurance, and HOA fees are included in the 28% threshold. Research average costs in your target area and subtract these from your 28% budget. This reveals your available mortgage payment budget.

Step 4: Use a Mortgage Calculator

Your mortgage payment depends on the loan amount, interest rate, and loan term. You can work backward: knowing your maximum payment, subtract property taxes and insurance to find your maximum loan amount.

Step 5: Check Your DTI Ratio

List all monthly debt payments. Divide your total monthly debt (including the new mortgage payment) by gross monthly income. This should not exceed 43% for most lenders.

Step 6: Consider Your Down Payment

If you have a 10% down payment saved, you can afford a house priced 10% higher than your maximum loan amount. A $300,000 loan with 10% down purchases a $333,333 home.

How to Use Our Affordable Home Price Calculator

Rather than working through these calculations manually, our affordable home price calculator does the heavy lifting for you. Simply enter your gross monthly income, down payment amount, current interest rate, and existing monthly debts. The calculator instantly shows your maximum affordable home price based on both the 28% and 36% rules, helping you identify a realistic budget before speaking with lenders.

Frequently Asked Questions

What if I don’t have a 20% down payment?

You can still buy a home with less. FHA loans allow 3.5% down, and many conventional loans accept 5-10% down payments. With less than 20% down, you’ll pay PMI (private mortgage insurance), which adds 0.5-1.5% annually to your loan amount. This increases your monthly payment but allows homeownership sooner. Calculate your total cost including PMI to compare affordability across different down payment scenarios.

Should I use the 28% or 36% rule?

Use both. The 28% rule is stricter and safer for your budget, as it limits housing costs alone. If you have minimal other debt, you might comfortably go higher. The 36% rule includes all debts but doesn’t guarantee lender approval. If your debts are high, focus on the 28% rule to maintain financial flexibility for emergencies and lifestyle expenses.

Can I afford a more expensive house if I get married or increase my income?

Yes, but only count stable, documented income. Marriage increases your combined income (if both partners have stable jobs), improving affordability. Promotions or raises increase your budget—but plan conservatively. Use current income as your baseline, and only upgrade your expectations if the income increase is permanent and documented. Avoid overextending based on projected future earnings.

Related: How Much House Can I Afford? The 28/36 Rule Explained