What is my debt-to-income ratio?

Both ratios divide monthly debt service by gross monthly income, which is annual income over twelve. At the example inputs, $100,000 a year is $8,333 a month before tax. The $2,000 housing payment alone is 24.0% of it: the front-end ratio. Adding $500 of other minimums makes $2,500 of total debt service, 30.0% of income: the back-end ratio.

Every program rules on the back-end number. They part company on the front-end one. Fannie Mae's Selling Guide limits the total ratio only, so on a conventional loan the housing figure is informational: a clean read on how much of the load is the roof rather than the loans. FHA and USDA publish a housing ceiling of their own, and it binds independently, which is why the calculator shows both numbers against both lines.

While you rent, the rent is the housing payment. When a lender qualifies you for a mortgage, it swaps the rent out for the proposed full house payment, principal, interest, tax, insurance, and dues, and recomputes the same two fractions.

There is no single maximum debt-to-income ratio, which is the part most pages skip. Each loan program publishes its own lines, and they do not agree with one another. This table is the one the calculator runs on: change the program in the calculator above and the band, the headroom, and the JSON all switch to the matching rows.

Conventional from Fannie Mae Selling Guide B3-6-02, Debt-to-Income Ratios (2025-04-02); FHA from HUD Handbook 4000.1 II.A.5, Approvable Ratio Requirements (Manual) (2026-08-12); VA from 38 CFR 36.4340, VA underwriting standards (2026-08-20); USDA from 7 CFR 3555.151(h), Rural Development guaranteed loan repayment ability (2026-08-20).

Three things the table cannot hold. FHA also allows 40/40 when the borrower carries no discretionary debt, and stretches to 33/45 on an Energy Efficient Home. VA's 41% is a standard rather than a cap: above it the lender must fully justify the approval in writing and the underwriter's supervisor must sign that statement, and the second-level review is not required at all when residual income exceeds the guidelines by at least 20 percent. USDA can exceed both of its ratios when the file documents compensating factors.

The practical consequence is that the same borrower gets different answers. Take $100,000 of income carrying a $2,800 housing payment and only $150 of other minimums: a 33.6% front-end ratio and a 35.4% back-end ratio. Conventional takes it inside the 36% line with $50 a month to spare. VA takes it inside 41%. FHA lands on the 47% line instead of 43%, because housing alone is $217 a month past the 31% ceiling, so the file needs a documented compensating factor. USDA refuses it on the housing test: $383 a month past 29%. One borrower, one set of numbers, four verdicts.

The 28/36 rule is a rule of thumb, not a limit any of the four programs publish. The FDIC's consumer material (FDIC Money Smart, Loans and Mortgages: How Much Mortgage Can I Afford?, last revised 2019-03-15) states it as a range rather than a pair of hard numbers: lenders usually require housing expenses at 25% to 28% of monthly gross income, which it calls the front-end ratio, and housing expenses plus long-term debt at 33% or 36%, the back-end ratio. The 36 half coincides with Fannie Mae's manual-underwriting line, which is most of why the rule stuck.

It is still a useful sanity check, because nothing on this page is tighter than it: no program here publishes a total line below 36% or a housing ceiling below 29%, so a borrower inside 28/36 is inside every line in the table above. At the example inputs, housing is 24.0% of gross income and total debt service is 30.0%, so this borrower clears both halves. If you want the rule as a dollar target rather than a percentage, the calculator's arithmetic panel prints the largest housing payment that still meets each line at your income and your other debts.

Search for a maximum DTI and something will tell you 43%, usually attached to the phrase qualified mortgage. That was true and is not. The CFPB's final rule at 85 FR 86308, published 2020-12-29, removes the General QM loan definition's 43 percent DTI limit and replaces it with price-based thresholds, which turn on the loan's rate against the average prime offer rate rather than on the borrower's ratio. It took effect 2021-03-01. Its mandatory compliance date was first 2021-07-01, and a second final rule at 86 FR 22844, published 2021-04-30, pushed that to 2022-10-01. Both dates are years behind us, so the 43% qualified-mortgage limit is not a live rule for any loan being written today.

FHA's 43% is a different 43. It comes from HUD Handbook 4000.1's manual-underwriting matrix, it is paired with a 31% housing ceiling, and it is current. If a page quotes 43% without saying which rulebook it is reading, that is the tell.

The default program's limits come from one primary source, Fannie Mae Selling Guide B3-6-02, Debt-to-Income Ratios, as of 2025-04-02: a maximum total ratio of 36% for manually underwritten loans, up to 45% with credit score and reserve requirements, and 50% as the Desktop Underwriter maximum. They are ceilings on the back-end ratio, not targets. Freddie Mac buys conventional loans too and publishes its own Seller/Servicer Guide; the conventional lines here are Fannie Mae's.

The useful translation is dollars, not points. At the example inputs, $2,500 of debt service on $8,333 of monthly income leaves $500 a month of room under the 36% line, $1,250 under 45%, and $1,667 under 50%. That is the car payment or card minimum you could add before crossing each line, and the calculator recomputes it for your numbers as you type.

Cross the top line and the dollars run the other way. The same income carrying $4,300 of debt service sits at 51.6%, $133 a month past even the 50% line; conventional approval at that ratio is unlikely, and the page says so rather than rounding the verdict off.

The ratio has one numerator and one denominator, so there are exactly two moves. On the numerator, paying off $100 of monthly minimums takes 1.2 points off the back-end ratio at the example income; clearing all $500 of minimums drops it to 24.0% and raises the headroom at the 36% line to $1,000 a month. Paying off a loan entirely removes its minimum; paying it down usually does not, which is why the last payment on a car loan moves the ratio and a big extra payment in the middle does not.

On the denominator, earning $5,000 more a year takes 1.43 points off at the example inputs, against 1.2 for the $100 of minimums above. Those two steps are the sizes people actually act in, not equal amounts of money, so which one wins depends on your numbers; the drivers list under the result ranks them for the ones you entered. What a raise does that debt repayment cannot is move every line at once: each line is a percentage of income, so all of them widen in dollars together.

The third move is not arithmetic at all: change the rulebook. A borrower who is over the line on one program and inside it on another has not changed a single number, and the program cards under the result price that swap directly.

Everything else underwriting looks at. Residual income, what is actually left after the bills, can sink an approval that the ratio alone would pass, and VA rules on it explicitly. Credit score and reserves decide whether the higher lines are available at all. The compensating factors that unlock FHA's 47% and 50% rows have to be documented in the file, not merely true. Individual lenders overlay stricter limits than any of the four rulebooks, and the automated systems, Desktop Underwriter, Loan Product Advisor, TOTAL, and GUS, return their own findings that can differ from the manual matrix in either direction.

The model also uses one income figure where the programs use several: FHA underwrites effective income, USDA uses repayment income for the ratios and adjusted annual income for eligibility, and every program verifies from documents, averages variable pay, and reads minimums off your credit report, which may not match what you type here. The ratio is arithmetic; the approval is a judgment this page does not make.

This calculator is built to be used without a browser. Every input is a query parameter on this page, and the same parameters on the JSON twin return the complete answer as a document.

GET /tools/dti.json?income=150000&housing=2500&debts=400&program=fha

The response carries inputs after parsing and clamping, result with both ratios as fractions, the band named after the program's own lines, each line with its allowed debt, its paired housing ceiling, your dollar headroom or overage, and the largest housing payment that still meets it, plus sensitivity.byProgram, which prices the same borrower against conventional, FHA, VA, and USDA in one call, drivers ranked by effect with a plain sentence each, assumptions that say for every field whether you supplied it and name the source when the default came from one, sources with a URL and an as-of date for each source the tool cites, which is an empty list on the calculators whose every default is an example input rather than a published figure, warnings, a disclaimer, and in tool the canonicalUrl and jsonUrl that carry only your non-default parameters. The canonical URL is the answer's permanent address; use it when you cite the number.

Parameters, all optional, in any order:

• income ($ per year), default $100,000 per year.
• housing ($ per month), default $2,000 per month.
• debts ($ per month), default $500 per month.
• program (one of conventional, fha, va, usda), default conventional.

Values accept plain numbers and loose human formats such as 100k, $100,000, or 6.5%. Unknown parameters are ignored, values outside a field's range are clamped and reported in warnings, and the endpoint never fails on bad input. Responses are cacheable for a day; the defaults change when their sources publish, and tool.version changes when the method does.

• Fannie Mae Selling Guide B3-6-02, Debt-to-Income Ratios, as of 2025-04-02. Manually underwritten loans: maximum total DTI 36%, up to 45% with credit score and reserve requirements. Desktop Underwriter: maximum 50%. The guide limits the total ratio only and sets no housing-only line.
• HUD Handbook 4000.1 II.A.5, Approvable Ratio Requirements (Manual), as of 2026-08-12. Manually underwritten mortgages, as housing ratio over total ratio: 31/43 with no compensating factor and for scores of 500 to 579 or no score, 37/47 with one documented factor, 40/50 with two, and 40/40 with no discretionary debt. Energy Efficient Homes stretch to 33/45.
• 38 CFR 36.4340, VA underwriting standards, as of 2026-08-20. Paragraph (d): the debt-to-income standard is 41 percent or less, and above it the steps in paragraphs (c)(1) through (c)(6) apply. Paragraph (c)(2) allows approval above 41 percent with justification by the underwriter's supervisor; paragraph (c)(4) is what requires the lender to fully justify that decision. Paragraph (c)(3) drops the second-level review and the statement of justification when residual income exceeds the guidelines by at least 20 percent.
• 7 CFR 3555.151(h), Rural Development guaranteed loan repayment ability, as of 2026-08-20. PITI plus homeowners' association dues, the annual fee, and other real estate assessments may not exceed 29 percent of repayment income, and PITI plus recurring monthly debts may not exceed 41 percent. Both may be exceeded with documented compensating factors.
• FDIC Money Smart, Loans and Mortgages: How Much Mortgage Can I Afford?, as of 2019-03-15. The 28/36 rule of thumb, stated as a range: lenders usually require housing expenses at 25% to 28% of gross monthly income (the front-end ratio) and housing plus long-term debt at 33% or 36% (the back-end ratio).
• CFPB final rule, Qualified Mortgage Definition Under the Truth in Lending Act (Regulation Z): General QM Loan Definition, as of 2020-12-29. 85 FR 86308. The final rule removes the General QM loan definition's 43 percent DTI limit and replaces it with price-based thresholds. Effective 2021-03-01, with a mandatory compliance date of 2021-07-01 that a later rule delayed.
• CFPB final rule, General QM Loan Definition; Delay of Mandatory Compliance Date, as of 2021-04-30. 86 FR 22844. Delays the General QM Final Rule's mandatory compliance date until October 1, 2022. Effective 2021-06-30.

The program lines are the sourced figures on this page, one primary document per program, plus the FDIC's statement of the 28/36 rule of thumb and the CFPB rule that removed the 43% qualified-mortgage limit. The income, housing, and debt defaults are examples to be replaced, not statistics.

Carlo is a personal finance agent. It knows your accounts, debts, and goals, so instead of a ratio on example numbers it can compute your actual debt-to-income from the accounts you link, watch it as balances change, and tell you what paying off one specific card would do to it. Text it the question.

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