How to Calculate DTI (And Why 43% Isn't a Hard Cutoff Anymore)
2026-07-31
Debt-to-income ratio, or DTI, is the single number most U.S. mortgage lenders look at first. It is not a credit score, it does not appear on your credit report, and it changes every time your income or minimum payments change — which is exactly why a spreadsheet you control is more useful than a number someone quoted you at an open house.
What Debt-to-Income Ratio Actually Measures
DTI compares your monthly debt obligations to your gross (pre-tax) monthly income. The Consumer Financial Protection Bureau defines it as “how much you owe each month compared to how much you earn,” and it is used as one signal — alongside credit score, assets, and employment history — of whether you can keep up with a new payment. It is not a promise of approval, and a low DTI does not override a weak credit file or thin cash reserves.
Front-End vs. Back-End: The Two Numbers Lenders Check
- Front-end DTI = proposed housing payment (principal, interest, taxes, insurance, HOA) ÷ gross monthly income
- Back-end DTI = every recurring debt payment, including the new housing payment, ÷ gross monthly income
Most conventional lenders quote a single back-end number, but FHA underwriting explicitly separates the two, which is why the guides below name both.
What Counts as Debt (and What Doesn’t)
Underwriters generally include the minimum payment on every account that reports to a credit bureau: credit cards, auto loans, student loans, personal loans, child support, and co-signed debt you’re still liable for. They generally exclude utilities, insurance premiums (outside of housing insurance), subscriptions, groceries, and debts someone else has assumed and can document paying. A common error is entering a full credit card balance instead of the minimum payment shown on the statement — that alone can overstate DTI by a wide margin.
Step-by-Step: Calculating Your Own DTI
- Pull your most recent pay stub or, if self-employed, your last two years of tax returns averaged monthly.
- List every recurring debt payment and its exact minimum from the current statement — not an estimate.
- Add the payments and divide by gross monthly income for back-end DTI.
- Add only the proposed or current housing payment and divide separately for front-end DTI.
- Recalculate after removing one debt to see how much room a payoff would create — this is the number a calculator is genuinely useful for, versus a static formula.
Worked Example: An $8,000-a-Month Household
A household with $8,000 gross monthly income, a $2,000 housing payment, and $400 in other required minimums has a 25% front-end ratio ($2,000 ÷ $8,000) and a 30% back-end ratio ($2,400 ÷ $8,000). If that household pays off a $150 auto loan payment entirely, back-end DTI drops to roughly 28.1% — a change worth modeling before, not after, a lender pulls the number.
Why 43% Stopped Being a Hard Cutoff in 2021
Many borrowers still hear “43% is the limit,” and it used to function that way under the original Ability-to-Repay/Qualified Mortgage rule. In 2021 the CFPB replaced the hard 43% cap for the General QM category with a price-based test tied to the Average Prime Offer Rate: a loan can qualify even above 43% DTI if its APR stays within a set margin of that benchmark. In practice, 43% survives as an industry rule of thumb rather than a legal wall, and Federal Reserve Bank of St. Louis research on more than 30 million mortgage applications found the sharpest jump in denial rates actually sits closer to 50% DTI, not 43%.
DTI Limits by Loan Type
- FHA: HUD’s standard benchmark is 31% front-end / 43% back-end, but manually underwritten files with documented compensating factors — cash reserves, residual income, minimal payment shock — can be approved up to roughly 50% back-end.
- VA: There is no statutory hard cap; lenders commonly use 41% as a guideline but frequently approve higher ratios when residual income (money left after debts and living costs) is strong.
- Conventional: Automated underwriting commonly allows back-end DTI up to about 45%, stretching toward 50% with strong credit, a larger down payment, or significant reserves.
These figures move with program updates, so treat them as the shape of the rule, not a substitute for your loan officer’s current guideline sheet.
Three Ways to Lower Your DTI Before You Apply
- Pay off or pay down the smallest installment loan entirely — a $0 balance removes the payment from the ratio completely, unlike a partial paydown on a card.
- Ask a lender whether a debt paid by someone else (a co-signed student loan the other borrower services) can be excluded with 12 months of documented payment history.
- Raise income the lender can count — a documented raise, a second job with a two-year history, or averaged bonus/commission income — rather than relying on future or projected pay.
Where These Numbers Come From
- Consumer Financial Protection Bureau — “What is a debt-to-income ratio?”, reviewed 2026-07-31
- CFPB — General QM loan definition (Regulation Z), reviewed 2026-07-31
- Federal Reserve Bank of St. Louis — “What 30 Million Applications Reveal about Mortgage Denial Thresholds,” June 2026, reviewed 2026-07-31
- FHA front-end/back-end benchmarks and compensating-factor exceptions come from HUD Handbook 4000.1, Section II.A.5; confirm current figures with your loan officer since manual-underwrite exceptions vary by lender overlay.
This guide is general education, not individualized financial, tax, legal, or lending advice, and it does not predict whether any specific application will be approved. Do not enter account numbers or other identifying information into a shareable URL.
Frequently Asked Questions
Is DTI the same as my credit score?
No. DTI is a cash-flow ratio; your credit score reflects payment history and credit usage. Lenders weigh both, along with assets and employment, separately.
Why did my lender’s DTI differ from what I calculated?
Lenders may use a different income averaging method (especially for bonuses, overtime, or self-employment), include or exclude different debts, or round differently. Ask which debts and income sources were used.
Does a lower DTI guarantee approval?
No. Credit history, appraisal, assets, and program-specific rules all factor into an underwriting decision; DTI is one input, not the whole decision.
Should I use gross or take-home income?
Use gross monthly income for any comparison against a lender’s published DTI limit — that is the standard those thresholds are built on.
When should I recalculate my DTI?
Recalculate after paying off a loan, taking on new debt, a documented income change, or before applying for any new financing, since even a small shift can move you across a program’s threshold.
Use the calculator
Open the related calculator, reproduce the worked example above, and then replace each value with your own verified statement figures.