Practical guide
How to Calculate Debt-to-Income Ratio
Compute DTI from debt payments and income for lending and budgeting decisions.
Quick Answer
Step-by-Step Method
- Add up your required monthly debt payments: mortgage or rent, car loans, student loans, and minimum credit card payments.
- Total your gross monthly income before tax, including salary, reliable bonuses, and documented side income.
- Divide total debt payments by gross income and multiply by 100.
- Optionally split the result into front-end DTI (housing costs only) and back-end DTI (all debt), since lenders assess both.
Worked Example
Gross monthly income is $6,000. Monthly obligations are a $1,500 mortgage, $400 car payment, $300 student loan, and $150 in credit card minimums — $2,350 in total. Back-end DTI = 2,350 ÷ 6,000 × 100 = 39.2%. Front-end DTI, counting only housing, = 1,500 ÷ 6,000 × 100 = 25%.
Detailed Explanation
DTI uses gross rather than net income purely as a standardisation convention — tax situations vary too much between borrowers to compare net figures fairly. The practical catch is that it makes your ratio look more comfortable than your bank account feels. A 39% DTI on gross income can easily be over half of take-home pay, which is why a technically approvable loan can still be a genuinely tight one.
Only required payments count, which creates a quirk worth knowing: credit cards enter at the minimum payment, not the balance. Someone carrying $20,000 in card debt might show only $400 in minimums and a healthy-looking DTI, while paying substantial interest. Conversely, paying off a small loan entirely removes its payment from the numerator and can move your ratio more than the balance size suggests.
The commonly cited thresholds — 36% comfortable, 43% the qualified-mortgage ceiling, and up to 50% for some government-backed programmes — are lender heuristics, not laws of personal finance. They also ignore everything DTI does not measure: savings, job stability, cost of living in your area, and dependants. Use it as a fast diagnostic and a lender-readiness check, not as a complete affordability verdict.
Use the Calculator
Run your real values in the interactive tool and review assumptions before taking action.
Open related calculatorFAQ
Does rent count toward DTI?
Yes. Housing cost is included whether you rent or own. For a mortgage application, lenders substitute the proposed new housing payment for your current rent.
Do utilities, groceries, or subscriptions count?
No. DTI counts only debt obligations. Living expenses are excluded, which is a key reason DTI alone understates how tight a budget really is.
What is the fastest way to lower my DTI?
Either eliminate a small loan entirely to remove its full monthly payment, or increase documented income. Paying down a large balance without clearing it changes DTI very little, since the required payment often stays the same.