Debt-to-Income (DTI) Ratio Calculator

The Formula

DTI ratio compares your monthly debt obligations to your gross monthly income and is the single most important number lenders evaluate during mortgage underwriting. Two versions are used: front-end (housing costs only) and back-end (all debts combined). Each has its own threshold that determines which loan programs you qualify for.

Variable Definitions

How to Use This Calculator

1. 1

   Enter all sources of gross monthly income before taxes and deductions, including salary, self-employment earnings, and stable side income.

2. 2

   Enter your proposed mortgage payment as PITI (principal, interest, taxes, and insurance) — this drives the front-end ratio.

3. 3

   Add all other monthly debt payments: auto loans, student loans, credit card minimums, personal loans, alimony, and child support.

4. 4

   Review your front-end and back-end DTI with the color-coded status gauge. Green indicates well-qualified, yellow means borderline, red suggests you should pay down debt first.

5. 5

   Use the "Max Debt" output rows to understand exactly how much additional monthly debt you could take on while staying within lender limits.

6. 6

   Experiment by adjusting individual debt amounts or adding income to see how much each change affects your DTI percentages.

Understanding the Concept

Debt-to-Income ratio is the single most important factor in mortgage underwriting because it measures your capacity to take on additional debt. Lenders evaluate two ratios: the front-end ratio compares only your housing costs to income and should stay below 28% for conventional loans. The back-end ratio includes all debt payments and should stay below 36-43% for conventional financing. FHA loans are more generous, allowing back-end DTI up to 50% if you have compensating factors such as a credit score above 700, significant cash reserves after closing, or a history of stable employment. VA loans have no strict DTI maximum but generally require residual income analysis. The color-coded gauge in this tool maps directly to lender guidelines: green (under 28% front-end or 36% back-end) means you are well-qualified; yellow (28-36% front-end or 36-43% back-end) is acceptable to many lenders but may require a stronger credit profile; red (above 43% back-end) means you may need to pay down debt, increase your income, or consider an FHA or non-qualified mortgage program. An important edge case: if you have significant assets or a large down payment, some lenders may be flexible on DTI limits. Self-employed borrowers should note that lenders use the net income from their tax returns, which is often much lower than gross revenue.

Frequently Asked Questions

Sources & References