What Is Debt-to-Income Ratio?
Debt-to-income ratio (DTI) is the share of your gross monthly income that goes to debt payments, including the proposed mortgage payment. It is used when lenders decide how much you can borrow, and matters because a high DTI can limit or block approval even with good credit and steady income.
Debt-to-Income Ratio in plain English
DTI is the share of your monthly income before taxes that already goes to debt. If you earn $7,000 a month and owe $2,100 in payments, your DTI is 30%.
Lenders look at it because it shows how much room your budget has for a new mortgage payment.
Advanced explanation
Debt-to-income compares recurring monthly debt obligations to gross monthly income. Underwriters typically look at a front-end (housing) ratio - the proposed principal, interest, taxes, insurance and HOA dues - and a back-end ratio that adds other recurring debts such as auto, student loan and minimum card payments. Maximum allowable DTI varies by loan program and by compensating factors such as reserves or credit score.
Formula
DTI = Total Monthly Debt Payments ÷ Gross Monthly Income × 100- Total Monthly Debt Payments
- The new housing payment (principal, interest, taxes, insurance, mortgage insurance, HOA) plus minimum payments on other debts.
- Gross Monthly Income
- Income before taxes and deductions that the lender can document.
Related forms: Front-End DTI = Monthly Housing Payment ÷ Gross Monthly Income × 100.
Worked example
Front-end and back-end DTI
Illustrative example - round numbers, not current market data. Calculated with Reaixo's calculator engines.
Assumptions
- Gross monthly income
- $7,000
- New loan
- $280,000 at 6.75%, 30 years
- Property tax and homeowners insurance
- $350 and $125 a month
- Car payment
- $400 a month
- Student loan
- $250 a month
- Credit card minimums
- $75 a month
| Step | Calculation | Result |
|---|---|---|
| 1. Principal and interest | $280,000 at 6.75% over 360 months | $1,816.07 |
| 2. Housing payment (PITI) | $1,816.07 + $350 + $125 | $2,291.07 |
| 3. Front-end DTI | $2,291.07 ÷ $7,000 × 100 | 32.7% |
| 4. All monthly debts | $2,291.07 + $725 | $3,016.07 |
| 5. Back-end DTI | $3,016.07 ÷ $7,000 × 100 | 43.1% |
Back-end DTI: 43.1%. About 43% of gross income would go to debt payments. That is above the 36% Fannie Mae uses as its base limit for manually underwritten loans, though automated underwriting can approve up to 50% with strong compensating factors.
What this calculation leaves out
- Lenders use gross (pre-tax) income and the minimum required payment on each debt, not what you choose to pay.
- Utilities, groceries and childcare are not in DTI - a loan you qualify for can still strain your budget.
Try it: Debt-to-Income Ratio with your own numbers
Interactive and illustrative: change any value and the results update instantly in your browser. The figures come from the same engines as REAIXO's full calculators.
Debt-to-income: the ratio lenders check
Lenders compare your monthly debt payments, including the new housing payment, with your gross monthly income.
- Back-end DTI (all debts)
- 43.1%
- Above 36%, within 45%
- Front-end DTI (housing only)
- 32.7%
- Room under 45%
- $134
- More monthly debt before 45%
- Base limit (0%-36%)
- Needs compensating factors (36%-45%) - you are here
- Automated approval only (45%-50%)
- Over the maximum (50%+)
- 36%: Manual underwriting base limit
- 45%: Manual, with strong credit and reserves
- 50%: Automated underwriting maximum
Show the numbers as a table
| Item | Monthly | Share of income |
|---|---|---|
| Housing payment | $2,291 | 32.7% |
| Other debts | $725 | 10.4% |
| Total debts | $3,016 | 43.1% |
| Gross income | $7,000 | 100.0% |
Formula
Back-end DTI = (Housing payment + Other monthly debts) ÷ Gross monthly income × 100Front-end DTI = Housing payment ÷ Gross monthly income × 100Assumptions
- Limits are Fannie Mae Selling Guide B3-6-02 reference points; FHA, VA and other lenders differ.
- Use minimum required payments; living expenses such as utilities are not debts.
Why it matters
Most conventional lenders cap total DTI around 43-50%, so a high DTI can limit how much home a buyer qualifies for even with strong income.
DTI often decides the maximum loan. With $7,000 of monthly income and $725 of other debts, every percentage point of allowed DTI is $70 a month of payment - about $10,500 of 30-year loan at a 7% rate.
What it means for you
How does it affect my budget?
A DTI a lender approves is a ceiling, not a recommendation; it does not count groceries, childcare, savings or repairs.
What professionals should verify
Confirm the qualifying payment for each debt (for example, how student loans in deferment are counted) under the specific program.
Common mistakes
- Using take-home pay instead of gross income.
- Leaving out a co-signed loan or a deferred student loan payment the lender will count.
- Taking on a car loan or new card balance between pre-approval and closing.
Compare and common questions
Debt-to-Income Ratio: frequently asked questions
What is the maximum DTI for a mortgage?
It depends on the program. Fannie Mae allows up to 36% for manually underwritten loans, up to 45% with stronger credit and reserves, and up to 50% through its automated underwriting system.
What debts are included in DTI?
Recurring debts that appear on your credit report or are documented - the new housing payment, car loans, student loans, minimum card payments, child support and alimony. Utilities, phone and insurance premiums other than homeowners insurance usually are not.
What is the difference between front-end and back-end DTI?
Front-end DTI counts only the housing payment; back-end DTI adds all your other monthly debts. Lenders focus mostly on back-end DTI.
How can I lower my DTI quickly?
Pay off or pay down a debt with a high monthly payment, add a co-borrower with documented income, or choose a lower price or larger down payment to shrink the new payment.
Go deeper
Recommended calculators
Run Debt-to-Income Ratio with your own numbers:
Where it fits
- Buying a home, Search & Affordability: next, Credit Score.
More Financing Terms
Recommended next step
Work back from your income and debts to a price you can carry.
Mortgage payment and affordability calculator →Apply it to a specific property: Buyer decision report.
Sources and review
- What is a debt-to-income ratio?, Consumer Financial Protection Bureau. Supports: DTI is total monthly debt payments divided by gross monthly income.
- Selling Guide B3-6-02, Debt-to-Income Ratios, Fannie Mae. Supports: Fannie Mae maximum DTI: 36% manually underwritten (45% with compensating factors), 50% through Desktop Underwriter.
Where this applies: United States. Federal disclosure rules apply nationwide; loan-program limits are set by each program (Fannie Mae shown) and individual lenders may be stricter.
Last reviewed: · Updated:
Examples use illustrative figures; rules of thumb are labelled as such. Rates, limits and program rules change - confirm current figures with your lender or a qualified professional.
This definition is provided for general educational purposes and is not financial, legal, tax, or real estate advice. Verify important decisions with appropriately qualified professionals.
Understand a property's costs and risks before you make an offer
Use the free calculator for your own numbers, or analyze a specific home before you commit.
- Free calculatorMortgage Calculator →Runs in your browser; nothing to sign up for.
- Paid reportHome Buyer Decision Report →Evaluate a home before making an offer. Price shown before checkout.
Or analyze a specific property: Essential Property Analysis, $19 · Property Decision Analysis, $49 · Professional Property Analysis, $99. You choose the depth before you pay.