Home Affordability Calculator

A home affordability calculator answers the single most important question in any home search: how much house can you actually afford? Not what a lender will approve — that number is often higher than what's comfortable. We're talking about the price range where you can cover the mortgage, keep saving for retirement, and still eat out once in a while. This guide breaks down the math behind the 28/36 rule, walks through a real scenario with specific dollar amounts, and shows where most buyers miscalculate.

What Does "Home Affordability" Actually Mean?

Affordability isn't a single number. It's a range defined by two constraints: what a lender will let you borrow (based on your debt-to-income ratio) and what you can sustain month after month without draining savings. A bank might approve you for $450,000, but if that mortgage plus taxes and insurance eats 35% of your gross pay, you're one car repair away from stress.

The Consumer Financial Protection Bureau (CFPB) recommends working backward from your monthly budget, not forward from a listing price. Start with how much you earn, subtract what you owe, and the remainder tells you the price range worth browsing.

The 28/36 Rule Explained

Lenders didn't invent the 28/36 rule out of thin air. Decades of loan-performance data show that borrowers who stay within these thresholds default far less often:

• 28% front-end ratio: Your total housing cost (principal, interest, taxes, insurance — the PITI payment) should stay at or below 28% of your gross monthly income.
• 36% back-end ratio: Your PITI payment plus all other monthly debt obligations (car loans, student loans, credit card minimums) should stay under 36% of gross income.

The binding constraint is whichever limit gives you the lower number. If you earn $6,250/month gross and have $600 in existing debts, the 28% rule caps housing at $1,750, while the 36% rule caps total debt at $2,250 — leaving $1,650 for housing. Your existing debts made the back-end rule the tighter constraint, trimming $100 off your budget.

FHA loans stretch the back-end limit to 43%, and some lenders go higher with strong credit and cash reserves. But qualifying for more doesn't mean affording more — those relaxed limits don't change how much groceries cost.

Worked Example: $75K Salary, $400/Month in Debt

Here's a scenario that matches what a large number of first-time buyers look like:

• Annual gross income: $75,000 ($6,250/month)
• Monthly debts: $400 (car payment + student loan minimum)
• Down payment: 10%
• Interest rate: 6.5%
• Property tax rate: 1.1%
• Homeowners insurance: $1,800/year

Step 1 — front-end limit: $6,250 × 0.28 = $1,750/month for housing.

Step 2 — back-end limit: $6,250 × 0.36 = $2,250 total. Subtract $400 in debts = $1,850 available for housing.

Step 3 — binding constraint:The front-end rule ($1,750) is stricter, so that's our ceiling.

Step 4 — solve for price: Working backward from a $1,750 PITI limit, after subtracting insurance ($150/month) and accounting for property taxes and principal-and-interest at 6.5% on a 90% loan, the maximum home price comes to approximately $283,000. That means a $28,300 down payment and a loan of about $254,700. Use our mortgage calculator to double-check the payment at any price point.

The conservative target — 25% of estimated take-home pay — drops that to around $225,000. The gap between the two numbers is your comfort zone to negotiate within.

Five Factors That Shift Your Price Range

Small changes in inputs move the needle more than most buyers expect:

• Interest rate (±0.5%): On a $250,000 loan, half a point changes the monthly payment by about $80 and shifts your affordable price by $12,000-$15,000. According to Freddie Mac's weekly rate survey, the 30-year average has swung over 400 basis points in the last three years.
• Property tax rate: The national average sits around 1.1%, but New Jersey runs 2.2% while Hawaii is under 0.3%. That difference alone can swing affordable price by $50,000+ at the same income.
• Existing debts: Every $100/month in existing debt reduces your back-end housing budget by $100/month — which translates to roughly $15,000 less home.
• Down payment size:A bigger down payment doesn't increase your monthly budget (the DTI formula ignores it), but it reduces the loan amount at a given price. Going from 5% to 20% down on a $300,000 home cuts the loan by $45,000 and eliminates PMI.
• Loan term: Switching from a 30-year to a 15-year term raises the payment by roughly 45% but saves over $100,000 in interest on a typical loan.

Common Affordability Mistakes That Cost Buyers

• Ignoring closing costs. Buyers budget for the down payment and forget the 2-5% closing costs due at signing. On a $300,000 home, that's $6,000-$15,000 in appraisal fees, title insurance, and lender charges you need on top of the down payment. Our closing costs calculator breaks down every fee so you can budget the full cash-at-closing amount.
• Using net income instead of gross. The 28/36 rule uses your pre-tax income. Plugging in take-home pay accidentally cuts your calculated budget by 20-30%.
• Forgetting ongoing maintenance costs. Budget 1-2% of the home's value per year for repairs and upkeep. A $350,000 home costs $3,500-$7,000 annually — that's $300-$580/month the DTI formula never accounts for. If you're unsure whether the listing price reflects fair market value, run a quick check with our home value calculator using comparable sales before committing.
• Maxing out the lender-approved amount.The bank qualifies you based on debt ratios alone. It doesn't know about your daycare bills, grocery budget, or retirement contributions. Buy at 90-95% of your approved max and you'll feel the squeeze within months.

What You Can Afford vs. What You Should Buy

The lender-approved maximum and the number you should target are almost never the same. Financial planners at firms like Vanguard and Fidelity generally recommend spending no more than 25% of take-homepay on housing — not 28% of gross. On a $75,000 salary, that's roughly $1,170/month versus $1,750. The difference is $580/month, or $6,960/year, that stays available for retirement, emergency savings, and life.

A useful mental model: the 28/36 rule tells you the ceiling. The 25% of take-home rule tells you the target. The range between them is where you decide how much cushion matters for your situation. Dual-income households with stable jobs can lean closer to the ceiling. Single earners or variable-income workers should stay closer to the floor. Once you've found your comfortable price range, our home buying calculator shows the full purchase cost — down payment, closing costs, monthly PITI, and total cash needed at closing — so you know exactly what that price range actually requires. And if you're considering new construction instead of buying existing, our cost to build a house calculator breaks down the full construction budget by category so you can compare apples to apples.

Down Payment Scenarios: 5%, 10%, and 20% Compared

The down payment doesn't change your DTI ceiling, but it reshapes the total cost dramatically. Here's how different down payments play out on a $300,000 home at 6.5% over 30 years:

The jump from 5% to 20% down saves $284/month in P&I alone, plus eliminates $140/month in PMI — a total monthly savings of about $424. Over 30 years, the 20% down option saves roughly $57,000 in interest. But you need $45,000 more cash upfront. If that cash would take you five extra years to save, there's a strong case for buying sooner at 10% down and refinancing once you hit 20% equity. Use our savings calculatorto map out how long it'll take to hit each target.

Tips to Stretch Your Home Buying Budget

• Pay down high-interest debt first. Every $200/month in debt you eliminate adds roughly $30,000 to your affordable home price. Credit card debt is the first target — it carries the highest rate and the largest monthly minimum per dollar owed.
• Shop rates from 3-5 lenders on the same day. Rate spreads of 0.25-0.5% between lenders are normal. On a $270,000 loan, that gap is $40-$80/month — which translates to $10,000-$20,000 in additional purchasing power.
• Consider a less expensive neighborhood. Property tax rates vary sharply even within the same metro area. A neighboring county with a 0.5% lower tax rate saves $1,500/year on a $300,000 home.
• Look into first-time buyer programs.Many states offer down payment assistance, below-market rates, or closing cost grants. These programs don't show up in generic rate comparisons — check your state's housing finance agency directly.
• Boost income before applying. A $5,000 raise pushes your 28% ceiling up by $117/month. If you're within 6 months of a promotion or review, it may be worth waiting to lock in a higher income on your application. Growing your savings in the meantime with a compound interest strategy makes the wait productive.

When to Use This Calculator

• Before your first conversation with a lender — walk in knowing your realistic range instead of letting them define it for you
• When you get a raise, pay off a debt, or your financial picture changes — recalculate to see how much more (or less) you can now afford
• Comparing neighborhoods with different property tax rates — plug in each area's rate to see the true price difference
• Deciding between a larger down payment vs. buying sooner with less cash — the scenario table shows the trade-off
• Selling your current home and buying the next one — run the home sale calculator first to estimate your net proceeds, then plug that amount in here as your down payment to see what you can afford