Front-End vs Back-End DTI
On this page
Front-end DTI divides monthly housing expense by gross monthly income; back-end DTI divides housing plus included recurring debts by gross monthly income.
The formulas
Front-end DTI = monthly housing expense / gross monthly income × 100. Back-end DTI = (monthly housing expense + included monthly debts) / gross monthly income × 100. State whether housing includes principal, interest, tax, insurance, mortgage insurance, and HOA; state which debts are included.
Worked example
With $8,000 gross monthly income, $2,000 total housing expense, and $700 other included debt, front-end DTI is 25.0% and back-end DTI is 33.75%. The $700 belongs only in the back-end numerator. If another calculator counts different obligations, its result can differ without either arithmetic result being wrong.
Why limits vary
CFPB says loan products and lenders use different DTI limits. Underwriting can also consider verified income, credit, assets, reserves, occupancy, property, and program rules. Treat preset ratios as scenarios unless they are tied to a current, cited program rule.
Income and debt definitions
Gross income is before taxes, but not every received dollar is necessarily qualifying income. Minimum card payments and recurring obligations may be treated differently by program. For an application, use the lender's definitions and documentation—not a self-created category.
DTI is not a household budget
DTI does not include every expense. A household with the same DTI may have very different childcare, healthcare, transport, utility, or savings needs. Pair DTI with a cash-flow budget.
Frequently asked questions
Does rent belong in mortgage DTI?
For a future owner-occupied purchase, treatment depends on the lender and transaction; follow the lender's instructions.
Is 28/36 mandatory?
No. It is a planning convention, not a universal rule.
Do utilities count?
They normally do not appear in standard DTI, but they matter to personal affordability.
Why use gross income?
DTI convention generally uses gross income, while a comfort budget can also examine take-home cash flow.
Sources
- CFPB affordability guidance: https://www.consumerfinance.gov/ask-cfpb/how-can-i-figure-out-if-i-can-afford-to-buy-a-home-and-take-out-a-mortgage-en-118/
- CFPB DTI definition: https://www.consumerfinance.gov/ask-cfpb/what-is-a-debt-to-income-ratio-en-1791/
- CFPB Loan Estimate: https://www.consumerfinance.gov/owning-a-home/loan-estimate/
Source research checked September 11, 2026. CalculatorGeek Algorithmic Team completed the calculation, source, and content review on September 11, 2026. This page provides educational estimates, not lending, legal, tax, or financial advice.
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