One of the most important questions you will face as a homebuyer is deceptively simple: how much house can you actually afford? The answer goes far beyond the maximum loan amount a lender will approve. It requires understanding the guidelines lenders use, accounting for costs that never appear on a listing page, and honestly assessing your own financial comfort zone.

Getting this number right protects you from becoming “house poor” — a situation where your mortgage consumes so much income that you struggle to save, invest, or enjoy life. This guide walks you through the formulas, the hidden expenses, and the practical steps to arrive at a budget you can sustain for the long term. You can also run your own scenarios with our mortgage calculator.

The 28/36 Rule

The 28/36 rule is the most widely used guideline in the mortgage industry for determining how much a borrower can comfortably afford. It consists of two separate thresholds:

• The 28% rule (front-end ratio): Your total monthly housing costs — including principal, interest, property taxes, and homeowners insurance (often abbreviated as PITI) — should not exceed 28% of your gross monthly income.
• The 36% rule (back-end ratio): Your total monthly debt payments, which include housing costs plus all other recurring debts such as car loans, student loans, credit card minimums, and personal loans, should not exceed 36% of your gross monthly income.

To put this into concrete numbers, consider a household earning $6,000 per month in gross income (before taxes). Under the 28/36 rule:

• Maximum housing payment: $6,000 x 0.28 = $1,680 per month. This is the ceiling for your mortgage principal, interest, taxes, and insurance combined.
• Maximum total debt: $6,000 x 0.36 = $2,160 per month. If you already pay $400 per month toward a car loan and $200 toward student loans, only $1,560 is available for housing — less than the $1,680 the front-end ratio allows.

The lower of the two numbers is your effective ceiling. In this example, your existing debts reduce your maximum housing payment from $1,680 to $1,560. This is exactly why understanding both ratios matters, and why paying down existing debt before buying a home can dramatically increase your purchasing power.

Keep in mind that some loan programs allow higher ratios. FHA loans, for instance, may approve borrowers with back-end ratios up to 43% or even 50% with compensating factors. However, just because a lender will approve a higher amount does not mean you should borrow it. The 28/36 rule exists to give you breathing room for savings, emergencies, and everyday living expenses.

Understanding Debt-to-Income Ratio

Your debt-to-income ratio (DTI) is the single most important number lenders use to assess whether you can handle a mortgage payment. It compares your total monthly debt obligations to your gross monthly income, expressed as a percentage.

There are two types of DTI that lenders evaluate:

• Front-end DTI: Includes only housing-related costs (mortgage payment, property taxes, homeowners insurance, and HOA fees if applicable). Lenders typically want this below 28%.
• Back-end DTI: Includes all monthly debt obligations — housing costs plus car payments, student loans, credit card minimums, child support, and any other recurring debts. Most conventional lenders prefer this below 36%, though some will go up to 43% or 45%.

To calculate your back-end DTI, add up every monthly debt payment you are required to make and divide by your gross monthly income. For example, if your monthly debts total $1,800 and your gross income is $6,000, your back-end DTI is 30% ($1,800 / $6,000 = 0.30).

A lower DTI gives you several advantages beyond just qualifying for a loan. Borrowers with a DTI below 36% typically receive better interest rates, have more lender options to choose from, and face a smoother approval process. If your DTI is too high, consider strategies such as paying off a car loan, consolidating credit card balances, or increasing your income before applying. Even small improvements to your DTI can expand your affordable price range by tens of thousands of dollars.

If you are a first-time homebuyer, calculating your DTI early in the process gives you a realistic starting point and time to improve it if needed.

Hidden Costs of Homeownership

Many buyers focus exclusively on the mortgage payment and overlook the additional costs that come with owning a home. These expenses can add hundreds or even thousands of dollars to your monthly budget. Failing to account for them is one of the most common reasons new homeowners feel financially stretched.

• Property taxes: Rates vary widely by location, typically ranging from 0.5% to 2.5% of the home’s assessed value per year. On a $350,000 home in an area with a 1.5% tax rate, that is $5,250 per year, or about $438 per month added to your housing cost. Property taxes can also increase over time as assessed values rise.
• Homeowners insurance: Required by virtually all lenders, this typically costs between $1,000 and $3,000 per year depending on location, coverage level, and the home’s characteristics. Homes in areas prone to natural disasters may cost significantly more to insure.
• HOA fees: If you buy in a community with a homeowners association, expect monthly dues ranging from $100 to $500 or more. These fees cover shared amenities, landscaping, exterior maintenance, and sometimes utilities. Be sure to review the HOA financial statements, as special assessments for major repairs can add unexpected costs.
• Maintenance and repairs: A widely used rule of thumb is to budget 1% of your home’s value per year for maintenance. On a $350,000 home, that is $3,500 per year or about $292 per month. This covers routine upkeep like HVAC servicing, plumbing, roof repairs, appliance replacement, and landscaping. Older homes or properties with deferred maintenance may require even more.
• Utilities: Homeowners typically pay more in utilities than renters, especially if moving from an apartment to a larger house. Budget for electricity, gas, water, sewer, trash collection, and internet. Depending on the home’s size and energy efficiency, utilities can range from $200 to $500 per month.
• Private mortgage insurance (PMI): If your down payment is less than 20%, your lender will require PMI, which typically costs 0.5% to 1.5% of the loan amount per year. On a $300,000 loan, that is $1,500 to $4,500 annually, or $125 to $375 per month.
• Closing costs: While not a recurring expense, these one-time fees of 2% to 5% of the purchase price must be factored into your upfront budget. On a $350,000 home, that is $7,000 to $17,500. Read our closing costs guide for a detailed breakdown.

When you add these costs together, the true monthly expense of owning a $350,000 home can be $500 to $1,500 more than the mortgage payment alone. Always factor these in when determining your affordable price range.

How Your Down Payment Affects Affordability

The size of your down payment has a cascading effect on nearly every aspect of your mortgage. It determines your loan amount, your monthly payment, your interest rate, and whether you pay PMI. Understanding these connections helps you decide how much to put down.

Consider a home priced at $400,000 with a 30-year fixed-rate mortgage at 6.5% interest:

• 5% down ($20,000): Loan amount of $380,000. Monthly principal and interest of approximately $2,402. PMI required, adding roughly $190 to $475 per month until you reach 20% equity.
• 10% down ($40,000): Loan amount of $360,000. Monthly principal and interest of approximately $2,275. PMI still required but at a lower rate due to more equity.
• 20% down ($80,000): Loan amount of $320,000. Monthly principal and interest of approximately $2,023. No PMI required, saving you $150 to $400 per month compared to the 5% down scenario.

A larger down payment also often qualifies you for a lower interest rate, since lenders view borrowers with more equity as less risky. Even a quarter-point reduction in your rate on a $320,000 loan saves approximately $17,000 over 30 years.

That said, draining your savings for a larger down payment carries its own risks. Financial advisors generally recommend keeping an emergency fund of three to six months of expenses after closing. If putting 20% down would leave you with no cash reserves, a smaller down payment with PMI may be the safer choice. PMI is a temporary cost that goes away once you build enough equity, while having no emergency fund leaves you vulnerable to unexpected expenses.

Setting a Realistic Budget

Lender approval amounts and personal comfort levels are two very different things. A lender might approve you for $450,000 based on your income and credit, but that does not mean buying at that level is wise. Here is a step-by-step process for setting a budget that works for your actual life:

• Step 1 — Track your current spending: Before shopping for homes, spend two to three months tracking every dollar. Understand where your money goes so you can realistically assess how much you can redirect toward housing.
• Step 2 — Apply the 28/36 rule: Calculate your maximum housing payment using the formula described above. Then subtract estimated property taxes, insurance, and HOA fees to find the actual mortgage payment you can support.
• Step 3 — Account for lifestyle costs: Do not forget childcare, retirement contributions, travel, and discretionary spending. If your budget after housing leaves no room for these, you are probably overextending.
• Step 4 — Build in a safety margin: Target a housing payment that is 5% to 10% below your calculated maximum. This cushion protects you against property tax increases, insurance hikes, unexpected repairs, or temporary income disruptions.
• Step 5 — Run the numbers: Use our mortgage calculator to test different scenarios. Adjust the home price, down payment, and interest rate to see how each variable affects your monthly payment and total cost over the life of the loan.
• Step 6 — Stress test your budget: Ask yourself what happens if interest rates are half a point higher at closing, if property taxes increase next year, or if one earner in your household loses income for a few months. If your budget cannot handle these scenarios, consider a lower price range.

The goal is not to find the maximum amount you can borrow. It is to find the price range where you can own a home comfortably, continue building savings, and handle the inevitable surprises that come with homeownership.

Key Takeaways

• The 28/36 rule sets a practical ceiling: housing costs should not exceed 28% of gross income, and total debts should not exceed 36%.
• Your debt-to-income ratio is the key metric lenders use. A lower DTI earns better rates and smoother approvals.
• Hidden costs — property taxes, insurance, HOA fees, maintenance (budget 1% of home value per year), utilities, and PMI — can add $500 to $1,500 per month beyond your mortgage payment.
• A 20% down payment eliminates PMI and often secures a better interest rate, but do not sacrifice your emergency fund to reach it.
• Always set your budget 5% to 10% below your calculated maximum to create a safety margin for unexpected expenses.
• Use our mortgage calculator to model different scenarios before you start shopping for homes.

Frequently Asked Questions

How much income do I need to buy a $400,000 house?

Using the 28% rule with a 20% down payment ($80,000), your $320,000 loan at 6.5% results in a principal and interest payment of about $2,023. Adding estimated property taxes ($400/month) and insurance ($150/month) brings total housing costs to roughly $2,573. Dividing that by 0.28 means you would need a gross monthly income of approximately $9,190, or about $110,000 per year. With a smaller down payment, the required income increases because the loan amount and PMI add to your monthly costs.

Should I buy at the maximum amount a lender approves me for?

Generally, no. Lender approval amounts reflect the maximum risk the lender is willing to take, not necessarily what is comfortable for your lifestyle. Lenders do not factor in groceries, childcare, retirement savings, or entertainment. Most financial advisors recommend spending well below your approved maximum — ideally targeting a monthly payment that leaves at least 20% of your take-home pay available for savings and discretionary spending.

What if my debt-to-income ratio is too high?

There are several strategies to lower your DTI before applying for a mortgage. Pay off smaller debts like credit cards or personal loans to remove those monthly obligations. Avoid taking on new debt such as car loans or financing furniture. If possible, look for ways to increase your income, such as a side job or negotiating a raise. Even reducing your DTI by a few percentage points can significantly expand the loan amount you qualify for and improve the interest rate you receive.

How do property taxes and insurance affect how much house I can afford?

Property taxes and insurance are included in lender calculations as part of your total housing cost. In high-tax areas, these expenses can consume a large portion of your 28% front-end ratio, leaving less room for the mortgage itself. For example, if $600 per month goes to taxes and insurance, and your maximum housing budget is $1,680, only $1,080 remains for principal and interest — which supports a significantly smaller loan than if taxes and insurance were half that amount. Always research local tax rates and insurance costs for the specific areas where you plan to buy.