The 28/36 Rule Explained: How Lenders Decide What You Can Afford

What the two numbers mean

The 28% (front-end ratio)

Total monthly housing cost shouldn't exceed 28% of gross monthly income. Housing includes principal, interest, property taxes, homeowner's insurance, HOA dues, and (when applicable) private mortgage insurance — collectively known as PITI (or PITIA when HOA is included). The formula: front-end DTI = (monthly PITI ÷ gross monthly income) × 100.

The 36% (back-end ratio)

Total monthly debt — the housing payment plus every other recurring obligation that reports to credit (auto loans, student loans, minimum credit-card payments, personal loans, child support, co-signed loans) — shouldn't exceed 36% of gross monthly income. This is the limit underwriters care most about because it captures your full obligation load, not just the mortgage.

Worked examples for 5 income levels

These figures use the strict 28/36 ceilings against gross monthly income. Assume the buyer has no other significant debt unless noted.

Want your exact number? Run your income, down payment, and rate through the affordability calculator — it applies the 28/36 ceilings automatically.

$50K salary ($4,167/mo gross)

• Max housing (PITI): $1,167/mo.
• Max total debt: $1,500/mo.
• At a 6.5% 30-year rate with 10% down and ~$300/mo for taxes + insurance, this supports a home around $135K–$150K.

$75K salary ($6,250/mo gross)

• Max housing (PITI): $1,750/mo.
• Max total debt: $2,250/mo.
• Supports roughly a $215K–$240K home with 10% down at ~6.5%. A $400 student-loan payment cuts the comfortable price by about $60K.

$100K salary ($8,333/mo gross)

• Max housing (PITI): $2,333/mo.
• Max total debt: $3,000/mo.
• Supports roughly a $310K–$345K home with 10% down at ~6.5%. This is the income band where the 28% front-end usually binds first — the back-end has slack.

$125K salary ($10,417/mo gross)

• Max housing (PITI): $2,917/mo.
• Max total debt: $3,750/mo.
• Supports roughly a $400K–$440K home with 10% down at ~6.5%. Closely aligned with the $400K mortgage payment math used by most lenders.

$150K salary ($12,500/mo gross)

• Max housing (PITI): $3,500/mo.
• Max total debt: $4,500/mo.
• Supports roughly a $490K–$540K home with 10% down at ~6.5%. With a $700 car payment and $300 in student loans, the back-end ratio binds before the front-end does.

Front-end vs back-end DTI: which one actually decides your approval?

In modern underwriting, the back-end (total DTI) is the binding number 80–90% of the time. Most conventional lenders quietly drop the front-end check entirely if your back-end is in range — Fannie Mae and Freddie Mac's automated underwriting (DU and LPA) prioritize the back-end ratio plus residual income. FHA still publishes both, with default maxes of 31% front-end and 43% back-end, and VA emphasizes residual income over either ratio.

The practical implication: if you have meaningful non-housing debt (car loan, student loans, credit cards), the back-end ratio is what's going to limit you. If you have almost no other debt, you'll usually hit the 28% front-end first because housing costs alone eat the budget. Either way, the 28/36 rule gives you a single sanity check before talking to a loan officer.

What lenders actually use in 2026 (program by program)

• Conventional (Fannie/Freddie): typically up to 45% back-end via automated underwriting; can stretch to 50% with strong compensating factors (reserves, high credit score, big down payment).
• FHA: 31% front-end and 43% back-end as baseline; up to 56.9% back-end with compensating factors and AUS approval.
• VA: no hard DTI cap, but lenders flag 41%+ for residual-income scrutiny. The VA's residual-income table is often more binding than DTI.
• USDA: 29% front-end, 41% back-end, with limited flexibility.
• Jumbo (non-QM and bank-portfolio): tighter — usually 38–43% back-end with 6–12 months of reserves required.

Even when a program permits 50%+ back-end DTI, those loans price worse: higher rates, larger reserve requirements, and stricter documentation. Staying near the classic 36% keeps both your approval odds and your loan pricing healthy.

FHA's 31/43 rule vs the conventional 28/36

FHA uses its own DTI ceilings — 31% on housing and 43% on total debt — that look more generous than the 28/36 rule but carry trade-offs. FHA is designed for buyers with lower down payments (as little as 3.5%) and credit scores starting at 580, so the higher DTI room is paired with mandatory mortgage insurance and tighter property condition rules.

Side-by-side comparison

• Front-end DTI ceiling: Conventional 28% (soft) vs FHA 31% (hard baseline, 40%+ with AUS).
• Back-end DTI ceiling: Conventional 36% (soft) / 45–50% (AUS) vs FHA 43% (baseline) / 56.9% (with compensating factors).
• Mortgage insurance: Conventional PMI drops at 78–80% LTV; FHA MIP usually lasts the life of the loan unless you put 10%+ down.
• Minimum credit score: Conventional ~620, FHA 580 (or 500 with 10% down).
• Down payment: Conventional 3–20%, FHA 3.5% minimum.

Practical takeaway: the FHA 31/43 ceilings often let buyers qualify for a similar-sized home with less cash up front, but the lifetime cost is higher because of MIP. If your DTI fits inside 28/36 and you have 5%+ down with a credit score above 680, conventional is almost always cheaper over the life of the loan.

VA loans, residual income, and why DTI alone doesn't apply

VA loans technically have no hard DTI cap, but underwriters flag any file above 41% back-end for extra residual-income scrutiny. Residual income is the dollar amount you have left each month after taxes, the new mortgage payment, all recurring debts, estimated utilities ($0.14 per square foot is the VA default), childcare, and federal income tax. The VA publishes minimum residual income tables by region and family size — if you clear them, DTI matters far less.

VA residual income minimums (Northeast, family of 4, illustrative)

• Loans under $79,999: ~$1,025/month residual minimum.
• Loans of $80,000+: ~$1,158/month residual minimum.
• Add ~$80/month for each additional dependent.
• Other regions (South, Midwest, West): lower minimums by 5–15%.

If your DTI is 47% but your residual income clears the table by 20%+, a VA file can still be approved without compensating factors. That's why the 28/36 rule, while still a useful comfort benchmark, is not the binding test for active-duty service members and veterans. For VA borrowers, the better question is: 'After the mortgage and every other obligation, do I clear the residual minimum by a comfortable margin?'

Why use 28/36 instead of the bank's maximum?

The maximum a lender will approve and the maximum you should sign for are different numbers. Lenders don't see your retirement goals, your childcare bills, your medical premiums, or the lifestyle you actually want. They see W-2s and credit reports.

• At 43% back-end DTI (a common ceiling), almost half of every paycheck is already promised before taxes, retirement, healthcare, or savings.
• Most CFP-style planners now recommend a tighter 25/35 — 25% housing, 35% total — to leave room for a 15% retirement contribution and a 3–6 month emergency fund.
• Buyers in high-cost-of-living metros (NYC, SF, Boston) often stretch to 35%+ on housing alone. It works in the short term but slows wealth-building dramatically.

Common mistakes borrowers make with the 28/36 rule

• Using P&I instead of full PITI — leaves out taxes, insurance, PMI and HOA, which can add 25–35% to the true payment.
• Calculating against take-home pay by accident — gross income is the lender-aligned baseline; mixing in net income inflates the apparent ceiling.
• Forgetting deferred student loans — lenders impute a payment (typically 0.5–1% of balance) even when the borrower is paying $0.
• Counting bonus or overtime income that lacks a 2-year history — most underwriters require two consecutive years of receipt to include it.
• Ignoring HOA and special assessments — condos and planned communities can add $200–$800/month that crushes the front-end ratio.
• Using today's rate quote with last year's pre-approval payment — even a 0.5% rate move changes the affordable price by ~6%.
• Treating approval as comfort — banks underwrite for default risk, not lifestyle. The 28/36 ceiling is where comfort and approval roughly coincide.
• Forgetting closing costs and cash reserves — even if DTI fits, an underfunded reserve account is a leading cause of last-minute conditional approvals.

How to apply the 28/36 rule in 60 seconds

1. Write down your gross monthly income (annual salary ÷ 12; add steady side income if it shows on tax returns).
2. Multiply by 0.28 — that's your max PITI.
3. Multiply by 0.36 — that's your max total monthly debt.
4. Subtract your existing minimum debt payments (auto, student, credit card minimums) from the 36% number. What's left is the realistic ceiling for your housing payment, even if it's below the 28% number.
5. Run that housing number through a mortgage calculator at today's rate to see the home price it supports.

How to use the 28/36 rule with our mortgage calculators

The 28/36 rule gives you ceiling numbers; our calculators turn those numbers into a real home price, a real monthly payment, and a real amortization schedule. Use them in this order for the fastest, most accurate read on your situation.

1. Start with the Affordability Calculator

The /how-much-house-can-i-afford calculator applies 28/36 directly to your income, debts, down payment and target rate. It returns a maximum home price along with the implied monthly PITI — the easiest place to start.

2. Stress-test the payment with the Mortgage Calculator

Drop the home price from step 1 into the /mortgage-calculator and add realistic property tax (1–1.5% of value), homeowners insurance ($1,200–$2,000/year), and PMI if your down payment is under 20%. Make sure the full PITI is still ≤ 28% of your gross monthly income.

3. Size your down payment

Use the /down-payment-calculator to weigh 5%, 10%, 15% and 20% scenarios. A larger down payment lowers PITI (and may eliminate PMI), which directly improves your front-end ratio and creates room for other debt.

4. Refinance check (existing homeowners)

If you already own a home, use the /refinance-calculator to recompute your DTI at a new rate. Refinancing into a lower payment can pull a stressed back-end ratio back inside 36% — the same math that helps a buyer also helps a homeowner.

5. Cross-check at a target home price

Worked examples like /mortgage-payment-on-a-400k-house and /how-much-income-do-you-need-for-a-300k-house run the 28/36 math at fixed price points so you can sanity-check the affordability calculator's output.

Use the calculator