Debt-to-income ratio, or DTI, is a comparison between recurring monthly debt payments and gross monthly income. It is useful for planning, but the ratio used by a lender depends on the application and its underwriting rules.
The basic calculation
Add the monthly debt payments being considered and divide by gross monthly income. Multiply by 100 to express the result as a percentage. Housing costs may be included in a front-end or total DTI measure.
For example, $2,400 in qualifying monthly debt divided by $8,000 gross monthly income produces a 30% DTI.
What can be different in practice
Lenders may use minimum credit-card payments, documented support obligations, property taxes, insurance, HOA dues, or a proposed loan payment. They may also use qualifying income rules rather than the amount that reaches your bank account.
Use DTI as a budget check
Try the proposed housing payment and stress the calculation with higher taxes, insurance, or rates. A qualifying ratio is not the same as a comfortable budget, especially when savings goals and irregular expenses are included.
A worked example
Worked example: $1,600 in existing monthly debt plus a proposed $1,200 housing payment equals $2,800. Dividing that by $8,000 gross monthly income gives a 35% total ratio before any lender-specific adjustments.
A ratio is a screening measure, not a spending recommendation. Add childcare, savings, taxes, and irregular costs that may not appear in a lender's qualifying calculation.
DTI is a useful lens on monthly obligations, but it should sit beside cash reserves, credit terms, and the complete household budget.
COMMON QUESTIONS
Frequently asked questions
Does DTI use gross income?
Common lending calculations use gross monthly income, but the lender's definition of qualifying income can vary.
Can a low DTI guarantee approval?
No. Credit, assets, documentation, loan-to-value, property, and program rules also matter.