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The single number that decides your mortgage, computed the lender's way.
DTI is the gate every loan application walks through first, and it is computed in a way that surprises people: gross income, not take-home, against housing plus minimum debt payments. This calculator shows both ratios, grades them against the real lending tiers, and converts the rules into the number you actually need — how much housing payment you have room for.
Mortgage shoppers use it before applying, so the lender's first gate is never a surprise — and the "max housing payment per rule" table converts an abstract ratio into a shopping number. The gross-vs-take-home FAQ explains why approvals always feel generous.
Conventional loans cap at 43% back-end for most borrowers (45–50% with strong compensating factors), FHA stretches to about 50%, and VA has no hard cap but uses residual income tests. The classic 28/36 rule (28% housing, 36% total) is the comfortable zone — approval above it is possible, but the budget gets tight fast.
Income is gross — before taxes — including salary, documented overtime, and provable side income. Debts are the minimum payments on your credit report: cards, car, student loans, personal loans, plus court-ordered payments. Renters: your CURRENT rent does not count once you are applying with a mortgage payment. Utilities, groceries, and subscriptions never count.
Paying OFF a small debt beats paying DOWN a big one: eliminating a $250/month car payment drops your back-end by 3+ points instantly, while the same cash against a credit card balance barely moves the minimum. The second lever is a co-borrower's income. Run both scenarios here before touching anything.
Before — lenders use gross income, which is why the approved payment always feels larger than your real budget can hold. Use the 36% "comfortable" row for planning your life and the 43% row only to know what you could be approved for.