Debt-to-income (DTI) ratio calculator

The number underwriters check before anything else

Back-end DTI — your proposed housing payment plus every other debt payment, divided by income — is usually the real ceiling on what you'll be approved for, even more than your credit score in many cases. It includes car loans, student loans, and minimum card payments; it does not include utilities or everyday spending.

Paying off a loan with a large minimum payment can improve this ratio more than paying down a bigger balance with a small minimum — underwriting cares about the monthly payment, not the total owed.

Read the full guide: DTI Ratio: What Mortgage Lenders Actually Look At →

Lenders calculate two ratios, not one

The number most people mean by "DTI" is the back-end ratio: all monthly debt obligations divided by gross monthly income. There's also a front-end ratio, which counts only the housing payment. Underwriting guidelines reference both, though back-end does most of the work in practice.

Two details trip people up. First, it's gross income, not take-home — which makes your ratio look better than your bank account feels, and is a real reason a technically approvable payment can still be uncomfortable to live with. Second, the housing figure is full PITI including taxes, insurance, HOA dues, and mortgage insurance, not the principal-and-interest number a rate quote shows.

What counts as debt, and what surprisingly doesn't

The rule is roughly: recurring obligations that appear on your credit report count; ordinary living expenses don't. That produces some counterintuitive results.

The credit card treatment is the one worth internalizing: only the minimum payment counts, regardless of balance or of how much you actually pay each month. A $12,000 balance with a $240 minimum affects your ratio by $240. This creates a genuinely odd incentive — paying a card down without closing it improves your ratio, while consolidating several cards into a personal loan with a higher fixed payment can make it worse.

Where the 43% figure comes from

You'll see 43% cited constantly as the DTI limit. It originates from the Qualified Mortgage framework, where it functioned as a threshold for certain lender protections. It is not a universal cutoff, and plenty of loans are approved above it.

Automated underwriting systems evaluate DTI alongside credit score, reserves, down payment, and loan-to-value together. A borrower at 47% DTI with excellent credit, twelve months of reserves, and 25% down often clears where a borrower at 41% with minimal reserves and a 620 score does not. The ratio is one input in a joint decision, not a gate you pass or fail in isolation.

What's true is that lower is meaningfully better, and that the space above roughly 45% narrows your options fast — fewer lenders, fewer programs, and less tolerance for anything else in the file being imperfect.

Moving the number before you apply

DTI responds faster than credit score does, because it's arithmetic rather than history. Three levers, in rough order of effectiveness:

Retire small balances entirely. Paying off a card with a $2,300 balance and a $65 minimum removes $65 from your monthly obligations. Paying $2,300 against a $19,000 auto loan removes nothing — the payment stays identical. Eliminating whole payments beats reducing large balances, which is the opposite of what interest-cost logic would suggest.

Don't open anything new. A financed sofa or a new car during underwriting can move your ratio enough to change the decision, and lenders re-pull credit before closing. This is the most common self-inflicted denial in the process.

Document all income. Bonus, overtime, and self-employment income generally count with a two-year history. If you have it and haven't documented it, you're understating the denominator for no reason.