The 28/36 Rule: Your Mortgage Affordability Blueprint
The 28/36 rule is the most widely used mortgage affordability guideline—housing costs shouldn't exceed 28% of gross income, and total debt shouldn't exceed 36%. Used by Fannie Mae, Freddie Mac, and most conventional lenders to assess loan qualification.
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Fannie Mae and Freddie Mac adopted the 28/36 rule as standard underwriting guidelines. FHA allows 31% front-end and 43% back-end with compensating factors. Paying off $500/month in debt can improve your back-end ratio by ~3% on $60K income. A 20% down payment eliminates PMI and reduces your front-end ratio.
Ready to run the numbers?
Why: Staying within the 28/36 rule significantly reduces the risk of financial stress and mortgage default. In expensive markets, many buyers exceed these limits—but doing so increases vulnerability to rate increases, job loss, or emergencies. Knowing your ratios helps you shop within your means.
How: Enter your monthly gross income, housing costs (PITI), property tax, insurance, and other debt payments. The calculator shows your front-end and back-end ratios and whether you meet conventional guidelines. Target 2–3% below limits for a safety buffer.
Run the calculator when you are ready.
📋 Quick Examples — Click to Load
📊 Front-End vs Back-End vs Thresholds
🍩 Housing, Other Debt, Remaining Income
📊 Max Housing at Different Income Levels
📈 Income Allocation as Income Changes
For educational purposes only — not financial advice. Consult a qualified advisor before making decisions.
💡 Money Facts
Fannie Mae and Freddie Mac adopted the 28/36 rule as standard underwriting guidelines
— Fannie Mae
In 2024, the median U.S. homeowner spent ~35% of income on housing—above the 28% guideline
— NAR
FHA allows 31% front-end and 43% back-end with compensating factors
— HUD
VA loans use a 41% residual income test instead of strict front-end limits
— VA
Paying off $500/month in debt can improve your back-end ratio by ~3% on $60K income
— CFPB
A 20% down payment eliminates PMI and reduces your front-end ratio
— Freddie Mac
The 28/36 rule is the most widely used mortgage affordability guideline, employed by Fannie Mae, Freddie Mac, and most conventional lenders. It sets the maximum front-end ratio (housing costs to income) at 28% and the back-end ratio (total debt to income) at 36%. While many buyers in expensive markets exceed these limits, staying within the rule significantly reduces the risk of financial stress and mortgage default.
Sources: Fannie Mae, Freddie Mac, Consumer Financial Protection Bureau, National Association of Realtors.
Key Takeaways
- • Front-end ratio = Housing costs ÷ Gross monthly income (target ≤28%)
- • Back-end ratio = (Housing + all other debt) ÷ Gross monthly income (target ≤36%)
- • Housing includes PITI: principal, interest, taxes, insurance, PMI, HOA
- • Lenders use gross income, not take-home pay, for DTI calculations
Did You Know?
How Does the 28/36 Rule Work?
Front-End Ratio (28%)
Housing costs (PITI) should not exceed 28% of gross monthly income. Example: $6,000 income × 28% = $1,680 max housing. Lenders use this to ensure you won't become "house poor"—spending too much on shelter and leaving little for other expenses.
Back-End Ratio (36%)
Total debt (housing + car, student loans, credit cards, etc.) should not exceed 36%. Example: $6,000 × 36% = $2,160 max total debt. This captures your full debt burden and protects against over-leveraging.
Qualification
You must meet BOTH ratios. Exceeding either can result in denial or require compensating factors (reserves, credit score). Some automated underwriting systems will approve up to 50% DTI with strong compensating factors.
Expert Tips
Loan Type DTI Limits
Different loan programs have different DTI limits. Conventional loans follow the strict 28/36 rule; government-backed loans often allow higher ratios.
| Loan Type | Front-End | Back-End | Notes |
|---|---|---|---|
| Conventional | 28% | 36% | Standard guideline |
| FHA | 31% | 43% | First-time buyer friendly |
| VA | — | 41% | Residual income test |
| USDA | 29% | 41% | Rural properties |
Frequently Asked Questions
What is the 28/36 rule?
A lending guideline: housing costs (mortgage, taxes, insurance) shouldn't exceed 28% of gross monthly income (front-end ratio), and total debt payments shouldn't exceed 36% (back-end ratio). Used by most conventional mortgage lenders.
What counts as housing costs?
Front-end ratio includes: mortgage payment (principal + interest), property taxes, homeowner's insurance, HOA fees, and PMI (if applicable). These are collectively called PITI. Does NOT include utilities or maintenance.
What counts as total debt?
Back-end includes: all housing costs PLUS car loans, student loans, credit card minimum payments, personal loans, child support, and any other monthly debt obligations. Does NOT include utilities, groceries, or subscriptions.
Can I get a mortgage if I exceed the 28/36 rule?
Yes. FHA loans allow up to 31/43. VA loans focus on 41% back-end. Some conventional lenders go to 50% DTI with strong compensating factors (high credit score, large reserves, stable income).
Is the 28/36 rule realistic today?
In expensive markets (SF, NYC, LA), many homeowners exceed these ratios. The national median home price requires ~35% of median income for housing. However, exceeding the rule increases financial risk.
How do I improve my ratios?
Increase income (side job, raises), reduce debt (payoff cards, consolidate), lower housing costs (smaller home, different area), increase down payment (reduces mortgage/PMI), or extend loan term (reduces monthly payment).
Key Statistics
Official Data Sources
⚠️ Disclaimer: This calculator is for educational purposes only. Actual lender DTI limits vary. Consult a mortgage professional for qualification advice. Not financial advice.
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