The 28/36 Rule: What Debt-to-Income Ratio Do You Need for a Mortgage?

Before a lender looks at the house, they look at your income and your debts — and reduce the whole question of “can this person afford the payment?” to a single percentage. That percentage is your debt-to-income ratio, and the shorthand lenders have used for decades to judge it is the 28/36 rule. Knowing your number before you apply tells you what you can realistically borrow, and — more usefully — which debt to attack first if you fall short. You can run your own figure with our debt-to-income ratio calculator; this guide explains what the number means and what lenders actually do with it.

Two ratios, not one: front-end vs back-end

The 28/36 rule is really two limits, and confusing them is the most common mistake.

The front-end ratio (the “28”) covers only your housing cost as a share of gross (pre-tax) monthly income. For a mortgage, “housing cost” is not just principal and interest — it is PITI: principal, interest, property taxes, and homeowners insurance, plus any HOA dues and mortgage insurance. The rule of thumb says keep this under 28% of gross monthly income.

The back-end ratio (the “36”) is the one that matters most. It adds every required monthly debt payment on top of housing: car loans, student loans, personal loans, and the minimum payments on your credit cards. The classic guideline caps this at 36% of gross income. Things that are not debt — groceries, utilities, phone bills, insurance you pay monthly — are deliberately left out, because they are not fixed obligations a court could enforce.

A quick worked example. On a $6,000 gross monthly income, the 28/36 rule points to about $1,680 for housing (28%) and $2,160 for all debt combined (36%). If you already pay $500 a month on a car and $150 on student loans, that $650 eats into the back-end room, leaving roughly $1,510 for the mortgage payment before you hit 36% — less than the front-end limit would suggest. That gap between the two ratios is why the back-end number is the binding one for most buyers.

What lenders actually accept in 2026

Here is the part the rule of thumb hides: 28/36 is a guideline, not a cutoff. It describes the comfortable zone, but real approvals routinely go past it.

• Conventional loans run through automated underwriting (Fannie Mae’s and Freddie Mac’s systems), which regularly approve back-end DTIs into the mid-40s — and up to around 50% when you have compensating strengths: a high credit score, meaningful cash reserves, or a large down payment.
• FHA loans are more flexible still, sometimes stretching past 50% back-end with strong compensating factors, because the loan is government-insured.
• The Consumer Financial Protection Bureau has long pointed to a 43% DTI as an important threshold — historically the ceiling for a “Qualified Mortgage” — and, more to the point, as the level above which borrowers are statistically more likely to struggle. You can generally borrow above it, but 43% is a sensible line to think hard before crossing. (See the CFPB’s guidance on debt-to-income ratio for the details.)

The practical takeaway: treat 28/36 as the “comfortable” answer and ~43% as the “still possible but getting tight” answer. A lender may approve you at 45%; whether you should borrow that much is a separate question, and one a payment that consumes nearly half your income tends to answer for you a few months in.

How to calculate yours

The math is simple enough to do on the back of an envelope:

1. Add up your required monthly debt payments — the future mortgage payment (PITI), plus car, student, and personal loans, plus your credit cards’ minimum payments.
2. Divide by your gross (pre-tax) monthly income.
3. Multiply by 100. That is your back-end DTI.

Two details trip people up. Use gross, not take-home, income — lenders always work from pre-tax. And use the minimum payment on revolving debt like credit cards, not what you actually pay, because the minimum is the only amount the lender can count on as a fixed obligation. Our debt-to-income ratio calculator handles both correctly and shows which approval band you land in; if you are working backward from an income to a payment you can carry, the affordability calculator applies the same lender math in reverse.

If your DTI is too high, fix the numerator first

When your back-end ratio comes in over the line, you have two levers: raise income or cut debt payments. Income is slow to move, so debt is usually where the fast wins are — and which debt you attack matters.

The most effective target is a debt with a high monthly payment relative to its balance, not necessarily the one with the highest rate. Paying off a car loan with a $500 payment and a $6,000 balance removes $500 from your back-end ratio for $6,000; paying off a credit card with a $60 minimum and a $4,000 balance removes only $60. For qualifying, the car loan is the better target even though the card charges more interest — a rare case where the DTI goal and the “kill-the-highest-rate” goal point in different directions. If a card is close to paid off, clearing it removes its minimum from the ratio entirely, which can nudge you under a threshold.

A word of caution on one popular move: rolling several card balances into a single personal loan can lower your monthly payments and therefore your DTI, but only if the new payment is genuinely smaller — and it converts flexible minimums into a fixed obligation. Model it honestly before you count on it; our debt consolidation calculator shows the real payment and total cost side by side.

Why the number is worth knowing before you apply

A mortgage pre-approval is partly a DTI check, and finding out you are over the line after you have picked a house is a bad time to learn it. Running the ratio first tells you three things: the payment you can realistically carry, the price range that implies, and the single debt whose payoff would move you the most. None of that requires a lender, a credit pull, or handing your details to anyone — our DTI calculator runs entirely in your browser, and nothing you enter is stored or sent anywhere.

Disclaimer: This article is for educational purposes only and is not financial advice. Figures are computed with the models described on our methodology page; actual loan terms depend on your lender and circumstances.