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Debt-to-Income Ratio: How Much House You Afford

How lenders calculate mortgage DTI, with the CFPB's 33 percent example. A planning explainer for the affordability tool, not personal advice.

Published: 2026-09-03

Key takeaways

  • The CFPB defines DTI as all monthly debt payments divided by gross monthly income. In its example, $2,000 of monthly debts on $6,000 of gross income is a 33 percent DTI.
  • Different loan products and lenders set different DTI limits. There is no single federal number that says how much house a household can carry.
  • Lenders often look at a front-end ratio (housing only) and a back-end ratio (housing plus other debts). This site's affordability tool defaults to a 36 percent back-end planning input.
  • A qualifying DTI is not the same as a comfortable budget. The calculator output is a planning range, not a statement of what you can afford and not a pre-approval.

Published: 2026-09-03

Debt-to-income ratio is a fraction, not a verdict on how much house you afford. Lenders divide monthly debt payments by gross monthly income. They use that percentage as one measure of repayment capacity.

This page explains the math the way the CFPB does, then shows how that math feeds our affordability calculator. It does not tell any reader what they can afford. It does not approve a loan or promise a payment.

How is debt-to-income ratio calculated?

The CFPB's formula is straightforward. Add the monthly debt payments, then divide by gross monthly income. Gross income is generally the amount earned before taxes and other deductions.

The bureau's worked example uses a $1,500 monthly mortgage, a $100 auto loan, and $400 of other debts. That is $2,000 of monthly debts. On $6,000 of gross monthly income, DTI is 33 percent.

Swap the numbers and the percentage moves. A larger housing payment, a car loan, or a student-loan installment all raise the top of the fraction. Overtime that is not counted, or debts that are omitted, can make a homemade percentage look better than the underwriting version.

What is the difference between front-end and back-end DTI?

Front-end DTI looks only at housing cost versus gross monthly income. Housing in that ratio is usually principal, interest, taxes, and insurance, and it may include HOA or mortgage insurance when those will be required.

Back-end DTI adds other required monthly debts: auto loans, credit-card minimums, student loans, and similar installments. When people say "DTI" without a modifier, they usually mean the back-end figure. The CFPB's $2,000 / $6,000 example is a back-end style total because it already includes the mortgage plus other debts.

Our affordability tool asks for a target back-end DTI and defaults to 36 percent. That 36 percent is a conservative planning input used on this site. It is not a federal cap and not a statement that 36 percent is the right payment for a household.

Is there one DTI limit for a mortgage?

No. The CFPB says different loan products and lenders have different DTI limits. That sentence is the rule of thumb worth keeping. A conventional automated file, an FHA file, and a VA file can clear at different ratios on the same income.

Older Qualified Mortgage rules used a 43 percent DTI test. The CFPB later replaced that fixed General QM cap with price-based thresholds and still requires lenders to consider and verify income, assets, and debts. The history lesson matters because 43 percent still appears in consumer articles. It is no longer a single federal ceiling for every mortgage.

Program pages on this site describe other underwriting context, such as residual income on VA files. Those notes are program background, not a personal limit. A lender overlay can sit lower than a published band. Compensating factors can sit higher. None of that is a promise that a given ratio will clear.

How does DTI feed the affordability calculator?

The affordability calculator starts with gross monthly income, subtracts the monthly non-housing debts you enter, and applies the target back-end DTI. It then solves for a home price whose principal, interest, tax, and insurance payment fits the leftover room.

Change the target DTI and the estimated price moves. Change the rate and the estimated price moves the other way, because a higher rate consumes more of the same payment cap. That is arithmetic, not a finding that the higher price is a good idea.

The tool is intentionally conservative. It does not assume bonus income, rental income, or aggressive compensating factors. If the result feels high against take-home pay, lower the target DTI in the form and rerun it. Lenders qualify on gross income. Households spend take-home pay.

DTI note: a calculator range is not "how much house you can afford" as a personal recommendation. It is not a pre-approval, a quote, or a commitment to lend. Written Loan Estimates from licensed lenders are the documents that carry real numbers.

What usually belongs in the monthly debt total?

Count debts that will still be due after closing and that underwriters treat as recurring: installment loans, revolving minimums, and the proposed housing payment. The CFPB example includes the mortgage, an auto loan, and other debts in one sum.

Do not subtract groceries, utilities, or childcare from the CFPB fraction. Those costs matter to a household budget and they do not all enter the standard DTI formula. That gap is one reason a qualifying ratio can still feel tight.

After you have a planning price, price the payment itself in the mortgage payment calculator and compare loan structures on the loan types page. DTI, credit, and down payment move together. No single ratio closes the file.

Disclaimer: this guide is for general education. It is not financial advice and not a statement of what any reader can afford. HomeMortgageOnline is not a lender or broker and does not take applications, lock rates, or issue pre-approvals.

Sources

  1. Consumer Financial Protection Bureau, What is a debt-to-income ratio? - https://www.consumerfinance.gov/ask-cfpb/what-is-a-debt-to-income-ratio-why-is-the-43-debt-to-income-ratio-important-en-1791/
  2. Consumer Financial Protection Bureau, Qualified Mortgage Definition under the Truth in Lending Act (Regulation Z): General QM Loan Definition - https://www.consumerfinance.gov/rules-policy/final-rules/qualified-mortgage-definition-under-truth-lending-act-regulation-z-general-qm-loan-definition/
  3. HomeMortgageOnline affordability calculator (36 percent default back-end planning input) - https://homemortgageonline.com/affordability-calculator.html

Frequently asked questions

How do you calculate debt-to-income ratio for a mortgage?

The CFPB says you add monthly debt payments and divide by gross monthly income. In its example, $1,500 mortgage plus $100 auto plus $400 other debts is $2,000. On $6,000 of gross income, DTI is 33 percent. Lenders may count debts differently. The percentage is not a personal affordability verdict.

What is a good DTI ratio to buy a house?

There is no universal good number. The CFPB says products and lenders use different DTI limits. This site's affordability tool uses 36 percent as a conservative back-end planning default. A lower target leaves more monthly slack. A higher qualifying ceiling is not the same as a comfortable payment.

Does a 43 percent DTI still qualify every mortgage?

No. Forty-three percent was the old General Qualified Mortgage DTI cap. The CFPB replaced that fixed cap with price-based QM tests and still requires lenders to consider and verify debts and income. Some programs still talk in 43 percent terms. That history is not a promise that 43 percent will clear.

Is the affordability calculator telling me how much house I can afford?

No. It estimates a home-price range from the income, debts, rate, and target DTI you enter. That is a planning range, not personal advice and not a pre-approval. If the result looks high against take-home pay, lower the target DTI and rerun the numbers. Confirm figures on written Loan Estimates.

Do utilities count in mortgage DTI?

Standard DTI uses recurring debt payments and the proposed housing payment, not a full household budget. The CFPB example includes mortgage, auto, and other debts. Utilities, food, and childcare still affect cash flow even when they stay outside the ratio. That is one reason qualifying math and lived-in budgets diverge.