How Much House Can You Afford? The 28/36 Rule and Beyond

Ask a lender how much house you can afford and you will get an answer to a different question: how much they are willing to lend you. Those numbers are not the same, and the gap between them is where overextended homeowners come from. Affordability is something you calculate for yourself — and the classic tool for the job is the 28/36 rule.

This guide works the rule from the ground up: what counts as a housing cost, how to run the two ratios on your own income, and how to translate a monthly payment budget into an actual purchase price at today’s rates. Along the way we will stress-test the result against the costs the rule ignores, because property taxes, insurance, and maintenance do not care what your ratio says.

Bring your gross monthly income and your current debt payments; that is all the raw material the math needs.

The 28/36 Rule in Plain English

The rule sets two ceilings, measured against gross monthly income (before taxes and deductions):

• Front-end ratio — 28%: total monthly housing costs should not exceed 28% of gross income. Housing costs means PITI: principal, interest, property taxes, and homeowners insurance — plus HOA dues and mortgage insurance if applicable.
• Back-end ratio — 36%: housing costs plus all other debt payments (car loans, student loans, credit card minimums, personal loans) should not exceed 36% of gross income.

You compute both, and the tighter one wins. A debt-free household is usually bound by the 28% front end; a household with a car payment and student loans is usually bound by the 36% back end.

The rule dates back to traditional underwriting standards, and it survives because it encodes something real: households above these thresholds have historically been far more likely to end up house poor — technically solvent, but with a budget so dominated by the house that saving, investing, and absorbing surprises become impossible.

Worked Example: What $96,000 a Year Buys

Take a household earning $96,000 gross ($8,000 per month) with a $450 car payment and $250 in student loan payments ($700 of monthly debt).

Step 1 — front-end limit: 0.28 × 8,000 = $2,240 maximum housing cost.

Step 2 — back-end limit: 0.36 × 8,000 = $2,880 total debt ceiling. Subtract existing debts: 2,880 − 700 = $2,180 available for housing.

Step 3 — binding constraint: $2,180 (the back end is tighter). That is the full PITI budget.

Step 4 — carve out taxes and insurance. Estimate property taxes and homeowners insurance for your target area — call it $450 and $150 per month here. That leaves 2,180 − 600 = $1,580 for principal and interest.

Step 5 — convert payment to loan amount. At 6.5% for 30 years, a mortgage costs $632.07 per month per $100,000 borrowed (the formula behind that figure is worked in full in how to calculate loan payments). So:

Loan amount = 1,580 ÷ 632.07 × 100,000 ≈ $250,000

Step 6 — add the down payment. With 10% down, price = 250,000 ÷ 0.90 ≈ $277,800. With 20% down, price = 250,000 ÷ 0.80 = $312,500 — and no private mortgage insurance, which frees up more of the budget.

Notice what the $700 of existing debt did: without it, the front-end $2,240 would bind, supporting a loan near $259,500 and a 10%-down price around $288,300. The car and student loans cost this buyer roughly $10,000 of house. Paying off a car before house shopping is often the highest-leverage move available.

A Quick Reference Table

Assuming 6.5%, 30 years, $600/month for taxes and insurance, no other debts (28% front end binds), 10% down:

Treat these as anchors, not answers — your property tax rate, insurance market, HOA situation, and debt load all move the result. Run your own numbers in the loan payment calculator with local estimates.

Rate Sensitivity: Why Half a Point Matters

Affordability is a moving target because it is leveraged to interest rates. Hold the $1,640 P&I budget fixed and vary the 30-year rate:

Each half point swings buying power by roughly $13,000–$14,000 on this budget. Two practical takeaways:

1. Your credit score is worth real money here. The spread between rate tiers can easily be half a point or more. Improving your score before applying — see how credit scores work — may buy more house than a year of extra saving.
2. Shop the rate. Multiple quotes within a short window count as one inquiry for scoring purposes, and studies cited by the Consumer Financial Protection Bureau show many borrowers leave meaningful money on the table by taking the first offer. Mortgage rates track the broader environment influenced by the Federal Reserve, so re-run your affordability math whenever rates move materially between pre-approval and offer.

The Costs the Rule Ignores

The 28/36 rule measures debt service. Owning a home costs more than debt service, and the gap is where budgets quietly fail.

Inside the payment (easy to underestimate)

• Property taxes vary enormously by state and even by school district — from well under 0.5% to over 2% of home value annually. On a $300,000 home that is a range of roughly $100 to $500+ per month. Get the actual figure for the specific property.
• Homeowners insurance has risen sharply in storm- and fire-exposed regions; quote it before you offer, not after.
• PMI typically runs about 0.3%–1.5% of the loan per year when you put down less than 20% — call it $60–$300+ per month on mid-size loans until you build enough equity to remove it.
• HOA or condo dues are contractually mandatory and belong in your front-end ratio even though some lenders display them separately.

Outside the payment (not in any ratio)

• Maintenance and repairs: a common planning figure is 1%–2% of home value per year — $3,000–$6,000 on a $300,000 house. Roofs, water heaters, and HVAC systems fail on their own schedule; a dedicated home sinking fund is the standard defense.
• Utilities usually rise when moving from an apartment to a house — more square footage, more systems.
• Closing costs of roughly 2%–5% of the loan, plus moving, furniture, and immediate fixes, all land in the first months.

A buyer at exactly 28% front-end with none of these funded is not at the edge of affordability — they are past it. This is why the down-payment phase should also build a post-closing cushion, a process mapped out in how to save for a house down payment.

Lender Limits vs. Your Limits

Here is the trap in the middle of the process: lenders routinely approve debt-to-income (DTI) ratios well above 36% — commonly up to 43%, and with strong compensating factors, sometimes toward 50% on certain programs. Your pre-approval letter reflects the lender’s risk tolerance, secured by a lien on the house. It says nothing about whether you can also fund retirement, childcare, travel, or an emergency fund.

Concretely, for the $8,000/month household: a 45% DTI approval implies $3,600 of total debt capacity — $2,900 for housing after existing debts, versus the $2,180 the 28/36 rule suggests. That $720/month gap is the difference between a budget with breathing room and one where every surprise goes on a credit card.

A sensible hierarchy:

1. Use 28/36 as your ceiling, not your target.
2. If your income is variable, or you have goals the ratios do not see (aggressive retirement saving, a child on the way, one income likely to pause), aim below it — 25% front-end is a common conservative choice.
3. Treat the pre-approval amount as the lender’s number, not yours. House-shopping 10–20% under it also strengthens your position as a buyer.

Stress-Test Before You Commit

Ratios are static; life is not. Before locking in a number, run these four checks:

1. The practice-payment test. For three months, transfer the difference between your rent and the projected full PITI + maintenance figure into savings. If it pinches, you have your answer before it costs you anything — and the transfers grow your down payment. Point the money at a target using the savings goal calculator.
2. The one-income test (for dual-income households). Can you cover PITI plus essentials on the larger income alone, even uncomfortably? If a job loss means immediate default risk, consider a smaller target.
3. The rate-bump test. If you are considering an adjustable-rate product, price the payment at the capped maximum rate, not the teaser. If the capped payment is unaffordable, so is the loan.
4. The full-budget test. Drop the projected housing cost into your actual monthly budget and confirm that saving, debt payoff, and normal life still fit. A 50/30/20 check is a fast way to see whether the house crowds out everything else in the “needs” bucket.

If the numbers survive all four, you are not just approved — you are actually ready. For the mechanics that come next (pre-approval, escrow, points, closing), continue with how mortgages work for first-time buyers, and if you want to understand why the early years of payments build so little equity, read loan amortization explained.

If the Number Comes Out Too Small: Levers That Actually Move It

When the math produces a price below what homes cost in your market, the answer is not to abandon the rule — it is to work the inputs. Ranked by typical impact:

1. Retire a debt payment. Every recurring payment you eliminate adds housing capacity dollar-for-dollar at the back end. Clearing the $450 car payment in the worked example frees $450 a month — enough to support roughly $71,000 more loan at 6.5%, almost certainly more than the payoff itself cost. Target the largest payments, not the largest balances: a snowball or avalanche plan that kills a whole payment beats one that dents a big balance without freeing any cash flow. Useful underwriting detail: lenders typically exclude installment debts with about ten or fewer payments remaining, so a modest lump sum that pushes a car loan under that line can remove it from your DTI entirely.
2. Bring a bigger down payment. Each extra $10,000 down is $10,000 of price at the same loan size — and crossing 20% deletes PMI from the front-end ratio, a double win.
3. Lower the rate. Credit repair, shopping multiple lenders, and (sometimes) paying discount points all convert into loan capacity at the $13,000-per-half-point exchange rate shown above.
4. Raise documented income. The slowest lever, with one catch worth knowing early: lenders qualify self-employed, commission, and bonus income using a two-year average from tax returns — income after business deductions, not gross revenue. If your income swings year to year, run the 28/36 math on a conservative-year figure and manage the gap with the techniques in budgeting on an irregular income; a great recent year that underwriting averages away buys you nothing.

What generally does not work: co-signing arrangements that paper over a payment problem, or loan programs that stretch DTI past 45% — those move the approval, not the affordability.

Common Affordability Mistakes

• Shopping at the top of the pre-approval. The most common and most expensive mistake; the lender’s max is not a recommendation.
• Using principal-and-interest as the whole payment. Taxes, insurance, PMI, and HOA can add 25–50% on top. Always budget full PITI.
• Ignoring existing debts. The back end binds for most buyers with car or student loans; run both ratios every time.
• Assuming today’s rent equals tomorrow’s capacity. Homes carry costs renting never showed you; the practice-payment test exposes the true delta.
• Stretching because “rates will fall and I’ll refinance.” Refinancing is possible, not promised, and it costs money. Buy the house that works at the rate you sign.

The Bottom Line

The 28/36 rule turns “how much house can I afford?” from a feeling into arithmetic: 28% of gross income for housing, 36% for all debt, whichever binds. From there it is mechanical — subtract taxes and insurance, divide by the payment-per-$100k factor at today’s rate, add your down payment — and out comes a price range grounded in your actual finances. For a $96,000 household with typical debts, that is roughly a $250,000 loan, not whatever a pre-approval letter happens to say.

Then respect what the rule cannot see: maintenance, rising insurance, one-income risk, and your other goals. Stress-test with the practice payment, keep a cushion after closing, and remember that every half point of interest moves your buying power by five figures. The best house you can afford is the one that still leaves you a functioning financial life after the boxes are unpacked.