Debt-to-Income Ratio: The Number That Decides How Much House You Can Buy
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How lenders calculate DTI, front-end vs. back-end ratios, worked examples at today's rates, and practical ways to improve your ratio before you apply.
When you apply for a mortgage, lenders look closely at three things: your credit, your cash, and your debt-to-income ratio, or DTI. Of the three, DTI is often the one that decides how big a loan you can get. It's also one of the least understood.
This guide explains how DTI is calculated, what lenders look for, and how to improve yours, with worked examples at this week's mortgage rates.
What DTI is
Your debt-to-income ratio is your total monthly debt payments divided by your gross (before-tax) monthly income. The CFPB defines it and explains why lenders use it: it's a measure of how much of your income is already committed, and so how much room you have for a new payment.
Included in DTI (typically):
- Your proposed housing payment: principal, interest, property taxes, homeowners insurance, mortgage insurance and HOA dues
- Minimum credit card payments
- Car loans, student loans and personal loans
- Child support or alimony you pay
Not usually included: utilities, groceries, phone bills, insurance other than homeowners, and other everyday living expenses.
Front-end vs. back-end DTI
Lenders often look at two versions:
- Front-end ratio: housing payment only ÷ gross monthly income.
- Back-end ratio: housing payment plus all other monthly debts ÷ gross monthly income.
When people say "DTI," they usually mean the back-end ratio. A long-standing rule of thumb is 28% for housing and 36% for total debt, but that's a guideline, not a rule. Actual limits depend on the loan program, your credit score, cash reserves and the lender's own standards, and can be higher in many cases.
Worked example: from DTI to home price
Let's walk through a buyer with $7,500 a month in gross income ($90,000 a year) and $500 a month in other debt payments (a car loan and a card minimum).
If the lender's back-end limit for this borrower were 43% (an illustrative figure), the most they could have in total monthly debts would be $3,225. Subtract the $500 in other debt and the maximum housing payment would be $2,725.
That housing payment has to cover more than the loan. Suppose property taxes, insurance and mortgage insurance come to $650 a month. That leaves about $2,075 for principal and interest. At this week's 30-year average of 7.32% (October 22, 2026), $2,075 a month supports a loan of about $302,068.
Now pay off the car loan, cutting other debts to $100 a month. The maximum housing payment rises to $3,125, leaving about $2,475 for principal and interest, which supports a loan of about $360,298. Clearing one debt raised the borrowing ceiling by roughly $58,230.
These numbers are illustrations, not approval amounts. Taxes and insurance vary a lot by location; check your state page for property tax rates, then run your own numbers in the affordability calculator.
Why "maximum" isn't the same as "comfortable"
Lenders tell you the most you can borrow, not the most you should. A DTI that fits a lender's limit can still leave a thin budget once you add utilities, maintenance, childcare, savings and everything else that doesn't count in DTI. Many buyers choose a payment well below their approval ceiling so they can keep saving and handle surprises.
A practical check: build a monthly budget that includes the new housing payment, about 1% of the home's value per year for maintenance as a planning figure, and your existing savings goals. If it doesn't work comfortably on paper, it'll be harder in real life.
How to improve your DTI
There are only two levers: lower debt payments or raise income.
Lowering debt payments
- Pay off small balances entirely, which removes the whole minimum payment from your DTI.
- Target debts with high minimum payments relative to their balance.
- Avoid taking on any new debt (car loans, financed furniture, new cards) before and during the mortgage process.
- Be cautious about refinancing or consolidating right before applying; new accounts can affect your credit score. See our debt payoff guide.
Raising documented income
- Lenders generally need income they can verify and expect to continue. New side income may need a track record, often two years for self-employment, before it counts.
- A co-borrower's income can count, but so do their debts.
Changing the loan
- A larger down payment lowers the loan amount and the payment.
- A lower rate, through shopping or points, lowers the payment. See how to compare mortgage rates.
- A cheaper area or lower property taxes can change the math significantly.
Student loans and DTI
Student loans count toward DTI. If you're on an income-driven repayment plan, the lender may use your documented monthly payment, but rules differ by loan program, especially for $0 payments or loans in deferment. Ask lenders how they'll treat your loans before you apply.
Common questions
Do lenders use gross or net income? Gross (before-tax) income is standard for DTI calculations. Since your budget runs on take-home pay, a payment that fits a lender's DTI limit can feel tighter in practice.
Does a co-signer help? A co-borrower's income can raise the income side, but their debts are added too, and they become responsible for the loan. Make sure everyone understands the obligation.
How do lenders treat self-employment income? Typically using tax returns, often averaging the last two years of net income after business expenses. Large write-offs can lower your qualifying income, so plan ahead if you're self-employed.
Tracking debts and income in one place
Improving DTI is mostly paying down debts and raising documented income. A household budget planner that lists every monthly obligation next to gross income makes the ratio easier to watch while you prepare to apply.
household budget planners on Amazon (Affiliate link. We may earn a commission.)
Practical takeaways
- DTI is your monthly debt payments divided by gross monthly income, including the new housing payment.
- Limits vary by program and lender; treat rules of thumb as starting points.
- Paying off a single small debt can raise your borrowing capacity noticeably.
- Your comfortable payment may be well below your maximum. Budget for maintenance and savings too.
- Get a preapproval to see how a lender views your DTI; see our preapproval guide.
When you are ready to shop, Compare first-time buyer loan options with a lender (Affiliate link. We may earn a commission.).
Sources
Rates are as of the dates noted and will change. Examples are illustrations, not loan approvals. This article is for education only and is not financial advice.
