The 28/36 Rule Explained: How Lenders Decide What You Can Afford
When you apply for a mortgage, the lender does not just look at your income and say "sure, that's enough." They run your finances through a set of ratio-based guidelines to determine how much debt you can safely carry. The most widely used guideline is the 28/36 rule -- and understanding how it works gives you a clear picture of what lenders will (and will not) approve.
What Is the 28/36 Rule?
The 28/36 rule sets two limits on your debt relative to your gross (pre-tax) monthly income:
- Front-end ratio (28%): Your monthly housing costs -- including mortgage principal, interest, property taxes, homeowner's insurance, and any HOA fees -- should not exceed 28% of your gross monthly income.
- Back-end ratio (36%): Your total monthly debt payments -- housing costs plus car loans, student loans, credit card minimums, and any other recurring debt -- should not exceed 36% of your gross monthly income.
These are also called debt-to-income (DTI) ratios. The front-end ratio measures housing debt alone, while the back-end ratio measures all debt combined.
How to Calculate Your DTI Ratios
The calculation is straightforward. Take your gross monthly income (your annual salary divided by 12, before taxes) and multiply by the ratio:
Max Total Debt = Gross Monthly Income × 0.36
Example: $75,000 Annual Salary
Gross monthly income: $75,000 / 12 = $6,250
- Max housing payment (28%): $6,250 × 0.28 = $1,750/month
- Max total debt (36%): $6,250 × 0.36 = $2,250/month
If you have a $400/month car payment and $200/month in student loans, your existing debt is $600/month. Under the back-end rule, you can carry up to $2,250 total, so your maximum housing payment would be $2,250 - $600 = $1,650/month. In this case, the back-end ratio is the binding constraint, not the front-end.
Example: $100,000 Annual Salary
Gross monthly income: $100,000 / 12 = $8,333
- Max housing payment (28%): $8,333 × 0.28 = $2,333/month
- Max total debt (36%): $8,333 × 0.36 = $3,000/month
With $500/month in existing debt, the back-end limit gives you a max housing payment of $2,500. Since the front-end limit is $2,333, the front-end ratio is the binding constraint here.
What Home Price Can You Afford?
The table below shows approximate affordable home prices at different income levels, assuming a 6.5% interest rate, 30-year term, 10% down payment, and $300/month for taxes and insurance. Existing non-housing debt is assumed to be $500/month.
| Annual Income | Max Housing (28%) | Max After Debt (36%) | Approx. Home Price |
|---|---|---|---|
| $50,000 | $1,167 | $1,000 | $125,000 |
| $75,000 | $1,750 | $1,650 | $240,000 |
| $100,000 | $2,333 | $2,500 | $360,000 |
| $125,000 | $2,917 | $3,250 | $465,000 |
| $150,000 | $3,500 | $4,000 | $570,000 |
| $200,000 | $4,667 | $5,500 | $775,000 |
The "Approx. Home Price" column uses whichever ratio is the binding constraint (lower number). Notice that at lower incomes, existing debt has a bigger impact because the $500 in monthly obligations eats a larger share of the 36% allowance. To get a personalized number, try our home affordability calculator.
Why Lenders Use These Ratios
The 28/36 rule exists because decades of lending data show that borrowers who spend more than these thresholds on debt are significantly more likely to default. The ratios are not arbitrary -- they represent the point where financial stress begins to cause missed payments, especially when unexpected expenses arise.
That said, the 28/36 rule is a guideline, not a hard law. Different loan programs have different limits, and lenders consider the full picture of your finances, not just two numbers.
When Lenders Make Exceptions
Many borrowers get approved with DTI ratios above 36%. Here are the main scenarios where lenders are willing to stretch:
Conventional Loans
Most conventional lenders will go up to 43-45% back-end DTI for borrowers with compensating factors. These include:
- Credit score above 740
- Down payment of 20% or more
- Significant cash reserves (6 or more months of mortgage payments in savings)
- Stable, verifiable income with a long employment history
FHA Loans
FHA-insured loans allow a front-end ratio up to 31% and a back-end ratio up to 43%. With strong compensating factors, some FHA lenders will approve DTIs up to 50%. FHA loans are popular with first-time buyers because they also allow down payments as low as 3.5%.
VA Loans
VA loans for military service members do not have a formal front-end ratio limit. The back-end DTI guideline is 41%, but VA lenders frequently approve higher ratios because VA loans have very low default rates due to the VA's residual income requirements.
Non-QM Loans
Non-qualified mortgages exist outside standard guidelines and may approve borrowers with DTIs of 50% or higher. These typically come with higher interest rates and are designed for self-employed borrowers or those with non-traditional income.
The 28/36 Rule vs. What You Should Actually Spend
Just because a lender will approve you at 36% DTI does not mean you should borrow that much. The 28/36 rule is a maximum, not a target. Here is why:
- It uses gross income, not take-home pay. If your gross monthly income is $8,333, your take-home might be $6,000 after taxes and benefits. A $2,333 housing payment is 28% of gross but 39% of your actual take-home pay.
- It does not account for savings goals. Retirement contributions, emergency funds, and other savings are not part of the formula. Maxing out your DTI can leave little room for saving.
- It ignores variable expenses. Childcare, medical costs, and other large but non-debt expenses are not factored in.
Many financial planners recommend keeping your housing costs at 25% or less of your gross income, and your total debt at 30% or less, to maintain a comfortable financial cushion.
Find Out What You Can Afford
Enter your income, debts, and down payment to get a personalized home price estimate based on the 28/36 rule.
Calculate AffordabilityHow to Improve Your DTI Before Applying
If your DTI is too high, you have two levers: reduce debt or increase income. Here are the most effective strategies:
- Pay off a car loan or credit card. Eliminating a $400/month car payment immediately adds $400 to your available housing budget under the back-end ratio.
- Avoid taking on new debt. Do not finance furniture, open new credit cards, or co-sign loans in the months before applying for a mortgage.
- Pay down credit card balances. Even if you pay in full each month, the minimum payment reported on your credit report counts toward your DTI.
- Increase your documented income. A raise, bonus, or documented side income can improve your ratios. Lenders typically need to see at least two years of history for self-employment income.
To see how different debt levels change what you can afford, experiment with our affordability calculator. You can also use our mortgage calculator to model different loan amounts and see exact monthly payment breakdowns.
The Bottom Line
The 28/36 rule is the standard framework lenders use to assess how much house you can afford. Your housing costs should stay at or below 28% of gross income, and your total debt payments at or below 36%. Lenders will sometimes approve higher ratios, but just because you can borrow more does not mean you should. Use the rule as a starting point, then adjust based on your take-home pay, savings goals, and other expenses to find a monthly payment that fits comfortably into your real-life budget.