The 39 and 44 percent figures come from CMHC's own qualifying guidelines and set the maximum a lender will approve, not a target to aim for. A lender also runs a stress test at a qualifying rate higher than your actual contract rate, so the number a calculator gives you before talking to a lender is often optimistic.
Existing debt eats into that ceiling before a mortgage payment is even considered: a car loan, a line of credit or several credit cards can shrink the 44 percent debt-service room significantly, which is why two households earning the same $200,000 can qualify for very different mortgage amounts.
A pre-approval from a lender, not an income multiple you read online, is the only way to know your actual number in today's rate environment. Get your hand-reviewed valuation from Joel Dyck.