What is the DTI formula?

Front-end DTI = (Housing payment) / (Gross monthly income) × 100. Back-end DTI = (Housing + all other monthly debt) / (Gross monthly income) × 100. Both must clear lender limits to qualify.

What is a good DTI ratio?

43% triggers QM (Qualified Mortgage) issues under Dodd-Frank.

What is the CFPB Qualified Mortgage rule?

The CFPB's 2014 QM rule (with 2021 General QM update) set a 43% back-end DTI cap for safe-harbor Qualified Mortgages. Loans above 43% DTI can still be made but lose the "safe harbor" presumption of ability to repay. The 2021 rule replaced the hard cap with a price-based test, but 43% remains the de facto soft ceiling.

How does FHA differ from conventional DTI?

FHA (HUD-insured) allows back-end DTI up to 43% with automated underwriting and up to 50% with compensating factors (Cash reserves, residual income). Conventional Fannie Mae allows up to 50% with strong credit + reserves under Desktop Underwriter (DU); the headline number is still 36%.

What VA loan DTI limits apply?

VA loans (for eligible US Veterans) have NO hard DTI cap, but lenders typically use 41% as a soft ceiling. Above 41%, the VA requires residual income (cash after all expenses) above region-specific minimums. The VA residual income test is the only one of its kind in US mortgage underwriting.

How does student loan IBR affect DTI?

For Income-Driven Repayment (IBR/PAYE/SAVE) student loans, lenders historically used a hypothetical 1% of balance per month. Fannie Mae 2023 update allows using the actual IBR payment if it is a positive value. Freddie Mac and FHA both updated to align. Use your actual monthly IBR payment in the calculator.

Are gross or net income used?

GROSS monthly income (pre-tax, pre-401(k)). Lenders use gross because tax brackets and pre-tax deductions differ wildly between borrowers. Self-employed borrowers use 2-year average of net business income from Schedule C.

Why does my credit card minimum count and not the full balance?

Per Fannie/Freddie/FHA underwriting, only the MINIMUM monthly payment on revolving accounts is included in back-end DTI. The full balance is NOT used (it shows up in credit utilization for the FICO score, which is separate). This is why paying down credit cards has dramatic DTI effects.

Can I lower my DTI to qualify?

Yes. The four levers: (1) pay off small revolving balances to drop their minimums; (2) lengthen auto loan term to lower monthly payment; (3) refinance student loans for longer term; (4) document additional gross income (bonus, OT, self-employment) with 2-year history.

What is residual income?

Residual income is cash left over each month after housing, debts, AND taxes — used by the VA in lieu of a hard DTI cap. The VA publishes region-specific minimums (e.g. $1,003/mo for Northeast family of 4 in 2026). Conventional loans do not check residual income.

How is DTI tied to the 1913 income tax?

The Sixteenth Amendment's 1913 Internal Revenue Act created the W-2 system that lenders rely on to verify "gross monthly income." Without IRS verifiable income there is no AGI line on tax returns, and without that there is no DTI calculation — DTI is downstream of the entire IRS income reporting framework.

Why is the pie center colored by DTI zone?

The center number turns emerald ( 36%) to give an at-a-glance verdict. The outer concentric ring shows the absolute zone limits per the CFPB, FHA, VA, and Fannie/Freddie thresholds discussed in the FAQ.

Pie + zone ring

Debt-to-Income (DTI) Calculator

To compute your DTI ratio, divide monthly debt by gross monthly income: Back-end DTI = total monthly debt / gross monthly income × 100. Underwriters use both Front-end (housing only) and Back-end (housing + all debt). The pie below color-codes against CFPB 43% QM, FHA 50%, and Fannie 36% conventional thresholds.

42.2%

Back-end DTI

27.9%

Front-end DTI

$2,870

Total monthly debt

High but possible (FHA/VA)

Verdict

28 / 36 / 43 / 50 — the four lines.

Quick Conversion

FROM (Debt ($))

TO (DTI (%))42.2059

gross/mo

Formula: DTI (%) = Total monthly debt / Gross monthly income × 100

DTI Pie + Mortgage Qualifying Zones

Inputs (monthly $)

Gross monthly income

Housing (PITI + HOA)

CC minimums

Auto loan

Student loan

Other debt

Label

Loan-file presets

Lender thresholds by program

Program	Front-end	Back-end
Conventional (Fannie Mae)	28%	36% (50% w/ DU)
Conventional (Freddie Mac)	28%	36% (45% w/ LP)
FHA HUD	31%	43% (50% w/ comp factors)
VA (Veterans)	No cap	41% soft + residual income
USDA Rural	29%	41%
Jumbo (non-conf)	28%	36-43% by lender
CFPB Safe Harbor QM	—	43% (legal cap)
Non-QM / DSCR	—	Lender discretion

Need to size a mortgage payment? Mortgage Calculator →

Formula

DTI (back-end) = Σ (debt payments) / gross monthly income × 100

Front-end = housing PITI / income. Back-end = housing + all installment + revolving minimums / income. Both expressed as %.

Worked: $1,900 housing + $970 other debt / $6,800 income = 42.2% back-end. Borderline FHA, fails conv.

From the 1913 Revenue Act to Dodd-Frank QM: how DTI became the loan gatekeeper

In 2026, a first-time buyer in Charlotte runs her file through a mortgage broker who asks for gross monthly income, housing PITI, and all monthly debts. The broker plugs into Fannie Mae's Desktop Underwriter and the system spits out a DTI score that decides whether she gets a 30-year loan. This page recreates that calculation.

The Sixteenth Amendment's 1913 Internal Revenue Act created the W-2 system that lenders use to verify "gross monthly income." Without IRS verifiable income there is no DTI calculation — DTI is downstream of the entire IRS income reporting framework. The 1913 act is the unsung enabler of every modern mortgage.

Frederick Macaulay's 1938 NBER work on bond duration laid the foundation for mortgage-backed securities. Lewis Ranieri at Salomon Brothers invented the modern MBS in 1977, securitizing FHA/VA loans into pools whose duration was Macaulay-equivalent. DTI ratios were already part of FHA underwriting from 1934 onward.

Harry Markowitz's 1952 portfolio theory (Nobel 1990) shaped how lenders think about credit risk diversification. A pool of 1,000 mortgages with average back-end DTI of 36% has materially lower default variance than a pool with a 50% average DTI — Markowitz's mean-variance framework underlies the entire MBS industry.

The 2008 financial crisis was largely a DTI failure. Subprime mortgages were originated with stated-income DTIs that bore no resemblance to reality. The Dodd-Frank Wall Street Reform Act (2010) created the CFPB, which in 2014 implemented the Qualified Mortgage (QM) rule capping back-end DTI at 43% for safe-harbor loans. The 2021 CFPB rule replaced the hard 43% with a price-based test but 43% remains the de facto industry ceiling.

Michael Jensen's 1968 alpha framework is invoked by mortgage hedge funds today: non-QM loans (DTI > 43%) are pitched as "alpha" relative to the conforming Fannie/Freddie benchmark. Mortgage REITs and private credit funds buy non-QM at 6-7% yields versus 5% conforming, betting that the extra DTI risk is overpriced by the rating agencies.

By 2026, the CFPB's 2023 update to the QM ATR (Ability to Repay) rule allows VantageScore alongside FICO for credit scoring. The DTI cap remains 43% for safe harbor with the price-based exemption. Fannie Mae's DU 11.0 (2024) and Freddie Mac's Loan Product Advisor 5.0 both publish DTI thresholds borrowers must meet for AUS approval. This calculator matches the exact ratios those engines compute.

How to use the DTI calculator

Enter gross monthly income. Pre-tax salary + verified self-employment from 2-year tax average.
Enter housing PITI. Principal + interest + property tax + homeowner insurance + HOA + mortgage insurance.
Enter monthly debts. Credit card minimums (not balance), auto loan, student loan (actual IBR if applicable), other recurring debt.
Read the two DTI numbers. Front-end and back-end both shown. Both must clear lender limits.
Check the zone. Pie center lights green / amber / red against the FHA / Conv / QM ring.

DTI calculator — frequently asked questions

Have more questions? Contact us

What mortgage professionals say

4.9

Based on 5,870 reviews

“The 4-zone outer ring (28/36/43/50) is the cleanest visual I have seen of the CFPB QM thresholds. I show this to first-time buyers who keep asking "what is a good DTI" — the pie + ring answers it in one image.”

Aleksandra Magdalena Wiśniewska-Kowalczyk

Senior mortgage underwriter, Fannie Mae LLPA expert

May 22, 2026

“FAQ #5 on VA residual income is exactly right. The VA-loan veteran preset returns a 32% back-end DTI which is what I see daily on clean VA files. I link this to every borrower at pre-qual stage.”

Chukwuemeka Obinwa Chinedumere

VA-approved loan originator, residual income certified

April 29, 2026

“The overspent-household preset at 52% back-end DTI lights up red — it is exactly the file I have to walk away from. Visual makes the conversation with the borrower 10x easier ("you see why we cannot do this loan").”

Bronwyn Anthea van der Linde-Pretorius

Mortgage broker, FHA + conventional dual track

April 4, 2026

“I run every client through this before house-hunting. The QM 43% line is sacred at most banks and my clients now understand why I push to pay off the $200/mo auto loan before applying — moves them from amber to green zone.”

Mthembiseni Sibusisiwe Hlongwane-Khumalo

CFP, residential real estate planning

March 15, 2026

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