The 28/36 rule says you can afford a mortgage when your monthly housing costs stay below 28% of your gross monthly income and your total monthly debt stays below 36%. It’s the most widely used affordability benchmark in U. S. mortgage lending, and it gives you a more honest number than your lender’s pre-approval letter will.

Here’s the uncomfortable truth: getting pre-approved for $500,000 doesn’t mean you should borrow $500,000. Banks approve loans based on what they think you can repay, not what lets you sleep at night, fund your retirement, and still afford a blown water heater. The 28/36 rule exists to close that gap.

You already know buying a home is one of the biggest financial decisions of your life. You feel the pull to “get into the market” before rates shift or prices climb. This guide gives you a clear, math-based answer to how much mortgage you can actually afford, along with what to do if the numbers don’t work yet.

Key Takeaways
– The 28% front-end ratio covers PITI: principal, interest, property taxes, and homeowners insurance
– The 36% back-end ratio covers all monthly debt, including your mortgage plus car loans, student loans, and credit cards
– Getting pre-approved for more than the 28/36 limits is common; it doesn’t mean you should borrow that much
– On an $80,000 household income, the rule caps housing at roughly $1,867/month and total debt at $2,400/month
– Your back-end debt-to-income ratio is the single most important number lenders use to approve or deny your application

What Is the 28/36 Rule?

The 28/36 rule is a debt-to-income (DTI) framework that lenders and financial planners use to evaluate whether a mortgage payment is manageable. The Consumer Financial Protection Bureau defines DTI as one of the key factors lenders use in mortgage decisions. The 28/36 rule has two distinct parts, and both matter.

The Front-End Ratio: 28%

This compares your monthly housing costs to your gross monthly income. “Housing costs” means your full PITI payment:

• Principal: The portion that reduces your loan balance each month
• Interest: The cost of borrowing from the lender
• Taxes: Property taxes, typically escrowed into your monthly payment
• Insurance: Homeowners insurance, plus private mortgage insurance (PMI) if your down payment is under 20%

If your gross monthly income is $7,000, your maximum housing payment under the 28% rule is $1,960.

The Back-End Ratio: 36%

This compares all of your monthly debt obligations to your gross monthly income. It includes your housing payment plus:

• Car loans
• Student loans
• Credit card minimum payments
• Personal loans
• Child support or alimony

Same $7,000/month income: your total monthly debt ceiling is $2,520. If your mortgage payment is $1,960, you have $560 left for all other debt payments combined.

Why You Need Both Numbers

The front-end ratio makes sure your home is affordable on its own. The back-end ratio makes sure it’s affordable given everything else you owe. Most conventional lenders require a back-end DTI below 43-45%. The 36% target is more conservative and leaves genuine financial breathing room, which matters when your roof needs replacing.

How to Calculate Your Mortgage Affordability Using the 28/36 Rule

Follow these four steps to run the numbers for your situation.

Step 1: Determine Your Gross Monthly Income

Use your pre-tax income. If you’re salaried, divide your annual salary by 12. If you’re self-employed or work variable hours, use the average of your last two years of income. Lenders will do the same.

Include all consistent income: salary, freelance income, rental income, investment income. Exclude bonuses and overtime unless they’ve been consistent for at least two years.

Step 2: Apply the 28% Front-End Limit

Multiply your gross monthly income by 0.28. That’s your maximum monthly housing payment (PITI).

Step 3: Subtract Your Existing Monthly Debt

Take your 36% back-end limit and subtract all non-mortgage monthly debt payments. The remaining amount is what you can apply to housing under the back-end rule.

Example: Gross monthly income is $6,667. Back-end limit is $2,400. You have a $380/month car loan and $195/month in student loan payments. That leaves $1,825 for housing under the back-end rule, which is actually lower than the $1,867 front-end cap.

Your real affordability limit is the lower number: $1,825/month.

Step 4: Convert Your Payment Budget to a Loan Amount

At a 7% interest rate on a 30-year fixed mortgage, every $100,000 borrowed costs roughly $665/month in principal and interest alone, before taxes and insurance.

If your payment budget is $1,825/month and you estimate $380/month for taxes and insurance, you have $1,445 left for principal and interest. That translates to roughly a $217,000 loan at current rates.

The 28/36 Rule in Practice: Jamie’s Story

Jamie earned $95,000 a year as a registered nurse in Charlotte, North Carolina. When she started house hunting in early 2025, her lender pre-approved her for a $380,000 mortgage. The agent congratulated her. The number felt validating.

Before signing anything, she ran the 28/36 calculation herself.

Gross monthly income: $7,917. Front-end limit (28%): $2,217. Back-end limit (36%): $2,850. She had $315/month in student loan payments and no car payment. That left $2,535 for housing under the back-end rule.

The $380,000 mortgage at 7% would have cost $2,528 in principal and interest alone. Once she added $275/month in estimated property taxes and $115/month for homeowners insurance, her actual PITI would be $2,918, clearing both thresholds by hundreds of dollars.

Jamie bought a $292,000 home instead. Her PITI came to $2,175/month, comfortably under her front-end cap. She kept $342/month in flexibility. Four months later, her HVAC system failed. The $4,400 repair didn’t go on a credit card because her budget had room for unexpected costs.

The lender would have approved her for significantly more. The 28/36 rule told her the truth.

Your debt picture directly affects how much house you can afford. If your back-end ratio is too high, paying down existing balances before applying can make a significant difference. Compare debt payoff strategies to find the fastest path to a lower DTI.

When the 28/36 Rule Gets Complicated

Like any general rule, the 28/36 framework doesn’t fit every situation perfectly. Here’s where it breaks down and what to do instead.

High Cost-of-Living Cities

In San Francisco, New York, Seattle, or Miami, housing costs routinely push past the 28% threshold even for high earners. A $900,000 home with 20% down at 7% costs roughly $4,790/month in principal and interest alone. For that payment to fit within 28%, you’d need a gross monthly income of $17,100, or about $205,000 per year.

In these markets, many buyers accept front-end ratios of 30-35% as the practical reality of local housing costs. That’s a tradeoff worth acknowledging openly, not rationalizing away. The question becomes: can you handle this payment if your income drops 15%? Do you still have retirement contributions and an emergency fund? If yes, a slightly elevated ratio may be acceptable.

Variable or Self-Employment Income

Freelancers, commission-based earners, and business owners don’t have stable monthly income. Using your best month to calculate the 28/36 ratio is a mistake. Use a 24-month average, then stress-test it at 15-20% below that figure. If the mortgage still fits, you can absorb a slow stretch.

Heavy Student Loan Debt

David and Priya had a combined income of $148,000. By the front-end rule, they could theoretically afford $3,453/month in housing. But between them, they had $1,080/month in student loan payments. After the back-end rule, their actual housing ceiling dropped to $2,340/month, not $3,453.

They didn’t catch this before going under contract on a $430,000 home. The PITI came to $3,150/month. For two years, they made no retirement contributions. When they eventually downsized, the transaction costs alone cost them $22,000. The 28/36 rule would have identified the problem before they signed.

PMI Changes the Equation

If you put down less than 20%, PMI gets added to your housing payment. PMI typically runs 0.5-1.5% of the loan amount annually, which is $83-$250/month on a $200,000 loan. That entire amount counts toward your 28% front-end ratio and can meaningfully shift what you can afford.

Other Factors Lenders Use to Set Your Loan Amount

The 28/36 rule is your personal benchmark. Lenders look at additional criteria that may move your approval higher or lower.

Credit Score and Interest Rate

Your credit score determines your interest rate. A borrower with a 760 score might get a 6.9% rate; a borrower with a 640 score might get 7.9% on the same loan. On a $300,000 mortgage, that one-point difference adds about $180/month to your payment and roughly $65,000 in total interest over 30 years.

Before you apply, know where your credit stands. If your score is below 740, improving it before applying could meaningfully lower your monthly payment. Understand what affects your credit score and the fastest ways to improve it before you house hunt.

Down Payment Size

A larger down payment does three things simultaneously: it lowers your loan amount, eliminates or reduces PMI, and signals financial stability to the lender. The difference between 10% and 20% down on a $350,000 home is $35,000 upfront. But it eliminates roughly $175/month in PMI and reduces your loan principal by that same $35,000.

Loan Type

Conventional, FHA, VA, and USDA loans carry different DTI requirements. FHA loans allow back-end DTIs up to 50% in some cases. VA loans don’t have a stated maximum DTI, though individual lenders apply their own limits. Government-backed loans can open doors for buyers who don’t fit conventional guidelines, but each comes with its own costs and conditions.

Employment Consistency

Lenders want two years of consistent employment history, ideally in the same field. A job change right before applying, even at higher pay, can trigger additional documentation requirements and underwriting scrutiny.

How to Improve Your Mortgage Affordability Before Applying

If your 28/36 numbers don’t work today, these moves can change that before you apply.

Pay down high monthly-payment debts first. Eliminating a $400/month car payment raises your back-end ceiling by $400/month, which can unlock $60,000 or more in additional home-buying power at current rates. Target the debt with the highest payment relative to its balance for the fastest DTI impact.

Improve your credit score by 40-60 points. The biggest levers: pay credit card balances below 30% utilization, dispute inaccurate items on your credit report, and avoid opening new credit lines for the 12 months before you apply. Understanding what moves your credit score makes this process systematic rather than guesswork.

Save a larger down payment. Every additional dollar down is a dollar less borrowed. If you can cross the 20% threshold, you eliminate PMI entirely. Even $10,000 extra on a $300,000 loan removes about $55/month in PMI and reduces your base payment.

Track your current spending with intention. Before committing to a 30-year payment obligation, spend 60-90 days understanding where your money actually goes. Mapping out your housing budget in detail, including utilities, maintenance, and HOA costs alongside the mortgage payment, often reveals a more accurate number than the 28% rule alone. A good expense tracking app makes the math of what you can sustain much more concrete than guessing.

Build your emergency fund before closing, not after. Homeownership guarantees unexpected costs. An HVAC replacement, a roof repair, a plumbing emergency: these will happen. Closing on a home without a funded emergency fund means the first major repair goes on a credit card, which starts compounding against your financial progress immediately.

Most homebuyers underestimate the cost of ownership beyond the mortgage payment. Budget an additional 1-2% of your home’s value per year for maintenance and repairs. On a $300,000 home, that’s $3,000-$6,000 annually, or $250-$500/month you should factor in beyond your PITI.

Frequently Asked Questions About Mortgage Affordability

What exactly counts toward the 28% housing ratio?

The 28% front-end ratio covers PITI: principal, interest, property taxes, and homeowners insurance. PMI also counts if your down payment is under 20%. HOA dues are included by most lenders as well.

Can I get a mortgage if my DTI is over 36%?

Yes. Most conventional lenders approve mortgages with back-end DTIs up to 43-45%, and FHA loans allow even higher ratios in some cases. Fannie Mae’s guidelines allow DTIs up to 45% for standard loans and up to 50% with compensating factors. But qualifying for a loan and affording it comfortably are different things. A 43% back-end DTI leaves little room for anything going wrong.

How much house can I afford on a $60,000 salary?

On $60,000 per year ($5,000/month gross), the 28% front-end cap is $1,400/month for housing. The 36% back-end cap is $1,800/month total debt. After accounting for taxes, insurance, and any existing debt obligations, most buyers at this income level can comfortably afford homes in the $175,000-$215,000 range at current rates, depending on their specific debt load and down payment.

Does the 28/36 rule use gross or net income?

Always gross income, meaning pre-tax. Lenders calculate DTI ratios from gross income, and the 28/36 benchmarks are calibrated accordingly. Using your take-home pay will make your affordability look worse than the standard calculation.

What if my rent is already more than 28% of my income?

Many renters, especially in major cities, already spend 30-40% of gross income on housing. If that’s your situation, the 28/36 rule suggests buying a home at a payment similar to or lower than your current rent rather than stretching because ownership feels different. The math doesn’t change just because you’re buying.

How does the 28/36 rule work with a variable-rate mortgage?

Run the calculation at the highest possible rate, not the teaser rate. Adjustable-rate mortgages (ARMs) often start lower but can reset significantly. If the worst-case payment still fits within 28%, the product may make sense. If it only works at the initial rate, you’re taking on rate risk that the 28/36 rule is specifically designed to prevent.

The Bottom Line: How Much Mortgage Can You Afford?

The 28/36 rule gives you something your pre-approval letter won’t: an honest look at how much mortgage you can afford without sacrificing everything else in your financial life.

Rachel, a 35-year-old teacher in Denver, got pre-approved for $415,000 in late 2025. She ran the 28/36 calculation, factored in her car payment and student loans, and found her real ceiling was $290,000. She bought at $278,000. Two years later, she’s maxing out her 403(b), has a fully-funded emergency fund, and recently opened a brokerage account. Her colleagues who borrowed to the top of their pre-approval limits are still waiting to do any of that.

Here’s your action plan:

1. Calculate your gross monthly income and multiply by 0.28 for your housing ceiling
2. Subtract non-mortgage debt from 36% of gross income to find your back-end limit
3. Use the lower number as your true affordability ceiling
4. Add taxes, insurance, and PMI before comparing to any home’s actual payment
5. If the numbers don’t work today, use the months before applying to pay down debt, build your credit score, and save more down payment

You can afford a home. The goal is finding the one that keeps your entire financial picture healthy for the next 30 years, not just the one that gets approved.

For more on building a strong financial foundation before buying, see our guides on how the 50/30/20 budgeting rule can help you save for a down payment and how to start investing with $100 once you’re in your home.