The 28/36 Rule: How Much House You Can Actually Afford

The Rule That Survived Decades of Housing Markets

Spend no more than 28% of your gross income on housing, and no more than 36% on all debts combined. That's the 28/36 rule, and it's been the backbone of mortgage affordability advice since the 1980s. It survives because it works: at those ratios, most borrowers can actually make their payments, save for repairs, and survive a rough year.

But the rule is a rule of thumb, not a law — and the difference between the two has never mattered more. At 2026 rates near 6.625%, the same $90,000 income buys a meaningfully smaller house than it did at 3% in 2021, and property taxes and insurance now consume a bigger share of the housing budget than they used to. So let's do the math properly: what 28/36 means, how lenders actually use it, where it breaks, and how to run your own version.

What the Two Numbers Mean

The rule has two ratios, and confusing them is where budgets go wrong.

Front-end ratio: 28%

Your housing expense ratio. Total monthly housing costs — principal, interest, property taxes, homeowners insurance, PMI, and HOA dues — divided by gross monthly income. Note what's included: taxes and insurance are in the 28%, not optional extras. Lenders count them, and so should you.

Back-end ratio: 36%

Your debt-to-income ratio. Everything in the front-end, plus all other monthly debt payments: credit card minimums, car loans, student loans, personal loans, alimony and child support. Divide by gross monthly income. This is the number underwriters actually care most about, because it measures total monthly obligations against income.

Gross income means pre-tax. A $90,000 salary is $7,500 a month gross — but after federal and state taxes, Social Security, Medicare, and health insurance, most households take home $5,300 to $5,800 of that. The rule uses the bigger number. That's why the ratios feel comfortable on paper and tight in practice, and it's one of the strongest arguments for budgeting below the cap rather than at it.

The Worked Example: $90,000 a Year

Let's build the full picture for a $90,000 household. Gross monthly income: $7,500.

Gross monthly income: $90,000 ÷ 12 = $7,500. Caps are pre-tax figures per the standard rule.

Now the part most affordability articles skip: $2,100 isn't your mortgage payment. It's your mortgage payment plus taxes and insurance. In a median-tax county — roughly 1% of home value in property tax plus $150 a month in insurance — taxes and insurance run about $500 a month on a $400,000 home. That leaves $1,600 for principal and interest. At 6.625% over 30 years, $1,600 of P&I supports a loan of about $250,000 — which, with 20% down, prices at roughly $312,000.

So the 28/36 answer for a $90,000 income at today's rates is around $312,000 with 20% down, or less with a smaller down payment once PMI is added. Raise the rate to 7.5% and the same $1,600 buys only $286,000. Lower it to 6.25% and it buys $325,000. Rates are doing real work in that range.

How Debt Changes the Answer

The 36% back-end cap is the real constraint for most buyers, because few people carry zero other debt. Here's the same $90,000 income with different debt loads — $2,700 total debt cap, minus debts, minus $500 for taxes and insurance, all at 6.625% with 20% down:

Assumes $500/month combined property tax and insurance, 6.625% 30-year fixed, 20% down, no PMI. Figures rounded. Your county's tax rate shifts every row.

Read that table twice, because it's the single most useful output of the 28/36 rule. A $1,000 monthly debt load — one car payment plus student loans — cuts your affordable home price from $429,000 to $234,000. That's a $195,000 difference in house, driven entirely by obligations you already have. Paying down debt before house hunting is worth more than any down payment strategy you'll read about, and it's exactly what our DTI calculator is built to show.

Run your own income and debts through the affordability calculator to get the price range for your specific situation — then check it against the full PITI payment math so the taxes-and-insurance line doesn't ambush you.

What Lenders Actually Underwrite

The 28/36 rule is a personal-finance guideline. The lending system runs on related but different numbers, and knowing both keeps you from being surprised at the pre-approval stage.

• Qualified Mortgage (QM) limit: 43% back-end DTI. The CFPB's ability-to-repay rule gives a loan special legal protections if the borrower's DTI stays at or below 43% at closing. Above that, lenders must document compensating factors.
• Fannie Mae and Freddie Mac: up to 45–50%. The agencies' automated underwriting systems routinely approve back-end DTIs of 45%, and up to 50% with compensating factors like large cash reserves, high credit scores, or a big down payment.
• FHA: 43% for most borrowers (57% with strong compensating factors, though that's rare in practice). FHA's front-end limit is 31%, not 28%.
• VA: no hard DTI cap, but 41% is the practical guideline most lenders apply before requiring a manual underwrite.
• USDA: 41% is the standard ceiling for the guaranteed loan program.

Translation: you can often qualify with a 40–45% back-end ratio. Qualifying and thriving are different things. At 43% DTI, a $90,000 household has $3,225 of its $7,500 gross income committed to debt every month — before groceries, gas, utilities, and health care. That's the gap between what a lender approves and what a budget can survive, and it's why this guide treats 28/36 as the sane target even when 43% is available.

Where the Rule Breaks Down

The 28/36 rule is a blunt instrument, and it misfires in five situations worth knowing about.

1. High-tax states

The rule assumes taxes and insurance are a modest slice of housing costs. In New Jersey (2.23% effective rate), Texas (1.6%), or Illinois (1.95%), the tax line eats the P&I budget. On a $400,000 home in New Jersey, property tax alone runs about $743 a month — versus $93 in Hawaii. A household that fits the rule in Tennessee is priced out in New Jersey with identical income. Our state-by-state cost guide shows how wide that spread is.

2. High-income households

At very high incomes, the 28% cap understates what's safe. A household earning $300,000 can spend 35% on housing — $8,750 a month — and still have more leftover than a $90,000 household has in total. Conversely, low-income households often find even 28% too aggressive, because fixed costs (food, transport, utilities) don't scale down with income. The ratio works best in the middle of the income distribution.

3. Childcare and other fixed costs

Daycare in many metros runs $1,200 to $2,000 a month — more than the entire housing allocation for a median-income family, and it doesn't count in the 36% back-end ratio. Lenders don't see it; your budget absolutely does. If you have dependent care costs, subtract them from your debt capacity before applying 28/36, not after.

4. Rate environments

The rule was popularized when mortgage rates ran 7–10% and property values were lower. In the 3% era (2020–2021), 28% of income bought an enormous house relative to history. At 6.625% in 2026, the same ratio buys much less — the rule doesn't adapt, but you should: check current rates and re-run your numbers whenever rates move a half point.

5. The "rich house, poor cash" trap

Buying at exactly 28/36 leaves almost no slack for the two expenses that actually break homeowners: repairs and unemployment. Budgeting 24–26% instead of 28% buys a slightly smaller house and a much larger safety margin. The difference between $2,100 and $1,950 a month is the difference between an HVAC replacement being an annoyance and a crisis.

How to Run Your Own Version

You don't need to memorize the rule — you need to apply it with your real numbers. Here's the sequence:

1. Write down gross monthly income. Salary, bonuses you can count on, investment income, alimony received. Lenders use the same figure.
2. List every minimum debt payment. Cards, car, student loans, personal loans, child support. Minimums, not what you pay extra.
3. Compute your caps: income × 28% (housing) and income × 36% (all debts).
4. Subtract real taxes and insurance. Look up your county's effective property tax rate and get an insurance quote. Don't guess at 1% if your county is 2%.
5. Back into the price. The remaining P&I budget, at today's rate, tells you the loan you can carry — and with your down payment, the price. The affordability calculator does this in one pass.
6. Stress-test at +1%. Rates moved more than a point in 2025. If your house only works at today's exact rate, it doesn't work.

Then, before you get serious: get pre-approved. A pre-approval letter gives you the lender's actual underwriting limits, not just the rule's estimate — and in a competitive market, sellers want to see it.

The 28/36 Rule Across the Country

Because taxes and insurance are baked into the front-end ratio, the same income buys wildly different homes in different states. Take the $90,000 household with $500 in other debts — a $2,200 housing budget. Here's what that budget supports in four states with very different cost structures (all at 6.625%, 20% down):

Assumes $150/month insurance (higher in coastal and storm states), $2,200 housing budget, 6.625% 30-year fixed, 20% down. Effective tax rates from Tax Foundation data; your county rate will differ. Rounded.

The same family, same income, same rule: Hawaii supports $382,000, New Jersey supports $255,000 — a $127,000 gap driven entirely by property tax structure. This is why national "how much house" calculators mislead and why the affordability calculator asks for your actual tax rate. If you're comparing two metros, run the 28/36 math in both before the lifestyle comparison even starts. And check the affordability by city data to see where your income goes furthest.

Renting vs. Buying Under the Rule

The 28/36 rule has a sibling that applies to renters: the 30% rent guideline. And the two interact in a way worth noticing — the 28% housing cap is almost always higher than what renters are spending, because a mortgage payment bundles principal (savings) with the interest-and-tax costs that renting also covers. If you're currently paying $1,400 in rent on the same $7,500 gross income — 19% — the jump to a $2,100 mortgage payment is a 50% increase in housing cost, not a 6-point ratio move. The ratio hides the cash-flow shock.

That's the strongest argument for the rent-versus-buy decision being about timeline, not ratios. Buy when you'll stay long enough for the transaction costs — typically 5 to 7 years at today's rates — to amortize away. Sell in three years and the equity you built with your early principal payments (remember: only 16% of your first five years of payments is principal at 6.625%) won't cover the closing costs you paid to buy. The 2026 rent vs. buy analysis runs the full comparison for several markets, and the TruePITI calculator shows the payment side of the ledger.

How to Improve Your Ratios Before You Buy

The 28/36 rule is a snapshot — and you control both sides of the fraction. Every dollar of debt paid down or income added moves the number. Ranked by speed and impact:

1. Pay off the smallest credit card balances first. A $5,000 card at a $150 minimum is a $150 monthly obligation; eliminating it raises your back-end capacity by $150 — about $29,000 of home at 6.625%. The credit score guide covers the utilization strategy that speeds this up.
2. Refinance or extend high car payments. A $650 car payment that becomes $450 through a longer term frees $200 of monthly debt capacity — worth about $39,000 of home. This only makes sense if the car outlives the loan, so do the math before extending.
3. Wait for income to catch up. A raise from $90,000 to $100,000 adds $833 of gross monthly income — $233 of front-end capacity at 28%, worth roughly $45,000 of house. One promotion can move your price range more than a year of aggressive saving.
4. Reduce the housing side instead. A larger down payment shrinks the loan and kills PMI, and a lower rate from a better credit score shrinks the payment. Both lower the front-end ratio without touching income. Check what rate your score actually commands on today's rate table.

The order matters: debt elimination beats income waiting beats down payment stretching, because debt is the only lever with a guaranteed monthly effect. Run the before-and-after through the DTI calculator and watch your affordable price move.

The 43% Question: Testing the Upper Bound

The rule says 36%. Lenders routinely approve 43–45%. The difference between those numbers isn't academic — it's thousands of dollars of house. Here's what the upper bound actually costs.

On the $90,000 income, a 43% back-end ratio allows $3,225 of total monthly debt — $525 more than the 36% cap. With $500 of other debts and $500 of taxes and insurance, that's $2,225 of principal and interest: a loan of about $347,000, or a $434,000 home at 20% down. Compare that to the $332,000 the 36% rule supports, and the "extra" $102,000 of house is entirely financed by the tighter margin between your income and your obligations.

What does that margin buy or cost? Run the cash flow: at 43% DTI, $3,225 of the $7,500 gross goes to debt. Take-home is roughly $5,600. That leaves about $2,375 a month for everything else — groceries, utilities, gas, health care, savings, and the 1%-of-value maintenance budget we covered earlier. In most metros, that's a thin envelope with no room for a job loss, a medical bill, or a rate environment that pushes escrow payments up. Lenders underwrite the payment, not the life around it, which is exactly why the 28/36 guideline survives: it's the ratio at which the life around the payment still works.

If you're going to stretch toward 40%+, the compensating factors need to be real: a six-month emergency fund, stable employment, low other debts, and a payment you've actually lived on for a few months before closing. And run the stress test — the affordability calculator lets you set the ratio yourself, so you can see what 36% versus 43% buys before you commit to the risk.

Frequently Asked Questions

The Rule Is a Floor, Not a Ceiling

The 28/36 rule earns its reputation because it keeps people out of trouble. But it answers a lender's question — "can you make this payment?" — with a ratio that ignores your actual life. Your answer should be built from your real income, your real debts, your county's real tax rate, and a rate that's 1% higher than today's. If the house still works at 29/37, buy it. If it only works at exactly 28/36, keep looking.

Start with the affordability calculator, verify the payment with the full PITI calculator, and check your real debt picture in the DTI calculator. Then get pre-approved and shop with numbers a seller can't argue with.