Your debt-to-income ratio — DTI — is one of the first numbers a lender calculates when you apply for a mortgage. It answers a simple question: what share of your gross monthly income goes to debt payments? A high DTI signals tight margins if income drops or expenses rise. A low DTI tells underwriters you have room in your budget for homeownership. This guide defines front-end and back-end DTI, explains the widely cited 28/36 rule, and walks through how limits differ by loan type — and why DTI and credit score are evaluated together, not as substitutes.
What Is Debt-to-Income Ratio?
Back-end DTI equals total monthly debt payments divided by gross monthly income (before taxes). If you earn $90,000 per year, gross monthly income is $7,500. With $650 in non-housing debt and a projected $2,100 housing payment, total obligations are $2,750. DTI = $2,750 ÷ $7,500 = 36.7%.
Front-End vs. Back-End DTI
Front-end DTI — the housing ratio — includes only your proposed total housing payment: principal, interest, property taxes, homeowners insurance, PMI if applicable, and HOA fees. Back-end DTI adds every other recurring debt obligation on your credit report and application. Both matter: you can pass back-end limits while failing front-end housing ratio guidelines if the home payment alone consumes too much income.
The 28/36 Rule
The 28/36 rule is a decades-old benchmark: spend no more than 28% of gross income on housing and no more than 36% on all debts combined. It is a planning guideline, not a law. Many borrowers qualify above 36% back-end through FHA, VA, or automated conventional approval — but targeting 28/36 leaves cushion for maintenance, savings, and life surprises. See our 28/36 rule infographic for a visual breakdown.
Try it yourself — adjust the numbers below
Your Finances
Car loans, student loans, credit cards, etc.
≈ 12.7% of home price
Your Affordability Range
You can afford homes between $286,000 and $316,000
Based on a 6.25% interest rate and 36.7% debt-to-income ratio
Range assumes PMI of approximately $120/month included in payment
Recommended Price
$286,000
$1,878.66/mo · conservative
Maximum Price
$316,000
$2,103.38/mo · upper limit
Monthly Payment Breakdown
36.7%
Your DTI is elevated. You may still qualify but with fewer lender options.
Your 12.7% down payment triggers PMI. At your credit score (Good (670–739)) and 87.3% LTV, PMI costs approximately $120/month ($1435/year).
How to eliminate PMI:
Putting down $63,200 (20%) eliminates PMI and saves $1435/year.
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Max home price
$286,000 recommended
$316,000
DTI Limits by Loan Type
Conventional Loans
Conventional loans through automated underwriting (Desktop Underwriter / Loan Product Advisor) often allow back-end DTI up to 45–50% with a strong file, and occasionally higher when compensating factors are present — substantial reserves, high credit score, large down payment, or stable long-term employment. Manual conventional underwriting is stricter and typically references the 28/36 planning benchmark more closely.
FHA Loans
FHA manual underwriting standards reference a 31% front-end ratio (housing only) and 43% back-end ratio (all debts). FHA's automated underwriting system (TOTAL Scorecard) can approve higher — up to roughly 56.9% back-end in some cases with a 620+ credit score and compensating factors. In practice, many FHA lenders apply their own overlays and cap back-end DTI at 45–50% regardless of what automated approval allows. Always confirm your lender's actual limit before you count on the AUS ceiling.
VA Loans
VA loans have no official hard DTI cap set by the Department of Veterans Affairs. Roughly 41% back-end is a common lender benchmark, especially in manual underwriting — but VA weighs residual income (money left over after housing, debts, taxes, and family maintenance expenses) more heavily than the DTI percentage alone. Borrowers with strong residual income can be approved well above 41% back-end when the full file supports it.
| Loan Type | Typical DTI Guidelines | Key Detail |
|---|---|---|
| Conventional | Back-end up to 45–50% (AUS) | Occasionally higher with compensating factors |
| FHA | 31% front / 43% back (manual) | Up to ~56.9% back via AUS; many lenders cap at 45–50% |
| VA | No official hard cap | ~41% benchmark; residual income weighed heavily |
| USDA | ~41% back-end (manual) | Income limits also apply |
These are general guidelines — not guarantees. Lender overlays, loan purpose, and your complete application determine the actual limit you face. USDA rural loans commonly reference ~41% back-end under manual guidelines, with income eligibility limits as an additional constraint.
Why DTI and Credit Score Work Together
A high credit score does not offset an unsustainable DTI, and a low DTI does not erase serious credit issues. Lenders need both capacity to pay (DTI, income stability, reserves) and willingness to pay (credit history, payment patterns). A borrower with 760 credit and 52% DTI may still decline. A borrower with 640 credit and 32% DTI may approve with FHA. Optimize both before you apply — see our guide on how to lower your DTI before buying.
Key Takeaway
Calculate your front-end and back-end DTI before house hunting. Know your loan program's typical range, but target comfortable ratios — not the absolute maximum you might squeeze through automated underwriting.
This guide is for educational purposes only and is not financial advice. DTI limits vary by lender, program, and underwriting method. Confirm your ratios with a licensed mortgage professional.