Debt-to-income ratio: what lenders actually see
Before a lender looks closely at your credit score, they run one ratio: how much of your gross monthly income already goes to debt payments. That number — debt-to-income, or DTI — decides whether an application clears the first hurdle at all.
The formula
DTI = monthly debt payments ÷ monthly gross income × 100. "Debt payments" means recurring obligations — rent or an existing mortgage, car loans, student loans, minimum credit-card payments — not groceries, utilities or insurance, which don't count toward the ratio even though they leave your account every month too.
The bands lenders use
Roughly: 36% or under is Good — comfortable room for a new payment. Above 36% up to 43% is Caution — still approvable at many lenders but tighter. Above 43% is High — the point where many conventional mortgage programs stop qualifying you without compensating factors like a large down payment or reserves.
A real example
Take $5,000 a month in gross income, with a $1,300 rent payment, a $200 student loan payment and a $100 credit-card minimum.
- Total monthly debt:
1,300 + 200 + 100 = $1,600. - DTI:
1,600 ÷ 5,000 × 100 = 32%. - 32% is under 36%, so the flag reads Good — comfortable room by this measure.
One new loan can flip the flag
Now add a $400-a-month car loan on top of the same $1,600 in existing debt.
- New total:
1,600 + 400 = $2,000. - New DTI:
2,000 ÷ 5,000 × 100 = 40%. - 40% sits above the 36% line and below 43%, so the flag moves to Caution — a single $400 payment, 8 points of income, was enough to cross it.
That's the practical lesson: DTI doesn't care whether the new debt is "worth it," and it doesn't average out against income you'll earn later — it's a snapshot of committed payments against current gross income, and it can move a full band with one signature.
The other lever: income
DTI has two sides, and paying off debt isn't the only way to move it. Keep the same $2,000 in monthly debt from the car-loan example above, but raise gross income to $6,000 — a raise or a second income source: 2,000 ÷ 6,000 × 100 = 33.33%, back under the 36% line and Good again, with the debt unchanged. Lenders don't care which side of the ratio moved; only the result does.
Why gross income, not take-home
Lenders use gross (pre-tax) income deliberately — it's the figure on a pay stub and tax return that doesn't depend on withholding elections, so it's consistent to verify across applicants. It also means your real, spendable room is tighter than the ratio implies, since taxes come out of that same income before any bill gets paid.
What doesn't count — and why that's a gap
Because DTI only counts debt payments, two people with identical ratios can have very different actual budgets. Someone with no debt but a large daycare bill or an expensive car lease payment they're not counting will show a low, flattering DTI that doesn't reflect what's actually left over each month. Treat the ratio as one input a lender uses, not a complete picture of what you can afford.
Run your own numbers
The free Debt-to-Income calculator runs this instantly for your real income and debts — entirely on your device — so you can see which band you land in before a lender does.