Before you fall in love with a listing, there's one number worth knowing: the most house you can comfortably afford. That's not the most a lender will approve you for (those are two very different figures), but the amount that fits your life without making every month a squeeze.
The quickest way to estimate it is a decades-old guideline called the 28/36 rule. It says your housing payment should stay under 28% of your gross monthly income, and your total debt payments should stay under 36%. That's it. Those two percentages do most of the work.
This guide explains where those numbers come from, walks through a real example from income to home price, and shows the costs buyers routinely forget. To put your own income and debts in, the Mortgage Calculator on QuickFix.tools will turn a target payment into an estimated home price, including taxes, insurance, and PMI, in a few seconds.
The 28/36 rule in plain language
Lenders need a fast way to judge whether you can handle a mortgage. The 28/36 rule is the rule of thumb that underpins most of their thinking, and it splits into two tests.
The front-end ratio (28%). Your monthly housing payment shouldn't exceed 28% of your gross monthly income, meaning income before taxes. "Housing payment" here means the full thing lenders call PITI: Principal, Interest, property Taxes, and homeowners Insurance, rolled into one monthly figure.
The back-end ratio (36%). All your monthly debt payments combined (the housing payment plus car loans, student loans, credit card minimums, and any other recurring debt) shouldn't exceed 36% of gross monthly income.
The reason there are two tests is that they catch different problems. The 28% test asks "can you afford the house?" The 36% test asks "can you afford the house on top of everything else you already owe?" Whichever limit is lower is the one that constrains you, and for buyers carrying other debt, it's usually the 36% back-end ratio that bites first.
A worked example: from paycheck to price tag
Let's make it concrete. Say you earn $90,000 a year, which is $7,500 a month before taxes.
Step 1: Apply the 28% front-end test. 28% of $7,500 is $2,100. That's the most you'd put toward a total monthly housing payment.
Step 2: Apply the 36% back-end test. 36% of $7,500 is $2,700 for all debt combined. Suppose you already pay $400 a month toward a car loan and student loans. That leaves $2,700 − $400 = $2,300 for housing.
Step 3: Take the lower of the two. The front-end test allows $2,100; the back-end test allows $2,300. The binding limit is the smaller one: $2,100 a month for housing. Your existing debt didn't end up as the constraint here. But if it were $700/month instead of $400, the back-end test would have dropped your housing budget below $2,100, and it would govern.
Step 4: Turn the payment into a home price. This is the step people find hardest, because a $2,100 payment is not $2,100 of loan repayment. A chunk of it goes to property taxes, homeowners insurance, and possibly PMI, often around 20 to 25% of the total payment. That leaves roughly $1,640 for actual principal and interest.
At a 6.5% interest rate on a 30-year loan, $1,640 a month supports a loan of about $259,000. Add a down payment and you get your home price:
| Down payment | Home price you can afford | Cash needed for down payment |
|---|---|---|
| 10% down | ~$288,000 | ~$28,800 |
| 20% down | ~$324,000 | ~$64,800 |
So a $90,000 earner with modest existing debt is realistically shopping in the high-$280,000s to low-$320,000s, depending on how much cash they bring to closing. Notice that a larger down payment doesn't just reduce your loan; it raises the price you can afford for the same monthly payment, and at 20% down it also eliminates PMI.
Your numbers will differ with your income, debts, rate, and down payment. The Mortgage Calculator handles all four at once so you don't have to do this arithmetic by hand.
The costs buyers forget (and why "affordable" can still hurt)
The 28/36 rule covers PITI, but homeownership has expenses that never show up in a mortgage quote. Budgeting only for the payment is how people end up "house poor": technically approved, perpetually stretched.
- Maintenance and repairs. A common planning figure is 1% of the home's value per year, about $3,000 annually on a $300,000 home. Roofs, water heaters, and HVAC systems don't care about your budget.
- HOA fees. If the home is in an association, monthly dues can run anywhere from modest to several hundred dollars, and they're on top of PITI.
- Higher utilities. A house usually costs more to heat, cool, and power than the apartment you're leaving.
- PMI. If you put down less than 20%, expect private mortgage insurance added to your payment until you build enough equity, typically a few hundred dollars a month on a mid-priced home.
- Closing costs. Usually 2 to 5% of the loan amount, due at closing, separate from your down payment.
A good habit: take the maximum the 28/36 rule allows, then deliberately shop below it. The gap is your breathing room.
Why the bank may approve you for more than you should spend
Buyers are often surprised when a lender pre-approves them for a number well above what the 28/36 rule suggests. That's not a mistake. Lenders can and do stretch the back-end ratio higher, sometimes to 43% or beyond, especially for borrowers with strong credit.
But "approved for" is a ceiling, not a recommendation. The bank is assessing the risk that you'll default, not whether you'll have money left for retirement savings, travel, or an unexpected job change. The 28/36 rule is intentionally conservative because it's built around your financial comfort, not the lender's risk tolerance. When the two disagree, the lower number is the safer one to trust.
How to stretch your budget the right way
If the number you're landing on feels low, there are legitimate levers, and one trap to avoid.
- Pay down existing debt first. Every $100/month of debt you eliminate frees up roughly $100/month of back-end room for housing. Clearing a car loan can meaningfully raise your price ceiling.
- Increase your down payment. More cash down means a smaller loan and a lower payment, and crossing the 20% threshold removes PMI entirely.
- Improve your credit score before applying. A better score earns a lower interest rate, and even half a percentage point changes how much home a fixed payment can buy.
- The trap: a longer loan term. Stretching to a 40-year mortgage lowers the monthly payment but balloons the total interest you pay over the life of the loan. It makes the house look affordable while quietly costing you far more.
Frequently asked questions
Does the 28/36 rule use gross or net income? Gross: your income before taxes and deductions. This trips people up, because your take-home pay is meaningfully lower, which is part of why shopping below the maximum is wise.
What if I have no other debt at all? Then the back-end test rarely binds, and the 28% front-end test alone governs your budget. Being debt-free is one of the most powerful ways to maximize how much home you can afford.
Is 28/36 still realistic with today's home prices? In expensive markets, many buyers exceed it out of necessity, and lenders allow higher ratios. The rule remains a useful comfort benchmark even where it's hard to hit. The further above it you stretch, the tighter your monthly finances will feel.
How much should I save for a down payment? 20% avoids PMI and is the traditional target, but many loan programs allow far less down. The trade-off: a smaller down payment means a larger loan, a higher payment, and usually PMI, so you can afford less house for the same monthly budget.
Should I get pre-approved before I start looking? Yes. Pre-approval tells you the lender's ceiling and makes your offers competitive, but pair it with your own 28/36 estimate so you shop by your comfort number, not the bank's.
Estimate your own number
The example here is one income and one set of assumptions. Yours will move with your debts, your down payment, your interest rate, and your local property taxes, and small changes to any of those shift the answer by tens of thousands of dollars.
The free Mortgage Calculator on QuickFix.tools lets you enter your income, down payment, rate, and term, then estimates your monthly PITI and a realistic home-price range, including taxes, insurance, PMI, and HOA. No signup, no data collected; it all runs in your browser.
Start with the 28/36 number, then shop a little under it. The house you can comfortably afford is almost always the one you'll be glad you bought.
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This article is for general educational purposes and isn't personalized financial advice. Interest rates, tax rates, and loan terms vary; for guidance specific to your situation, consider speaking with a qualified mortgage professional or financial advisor.