Keep housing costs under 28% of gross income, and all debt payments under 36%.
The classic mortgage-qualification ratios lenders use. Above them, one bad month starts to cascade.
It is a US underwriting convention on gross income, so it travels badly to countries with much higher tax and social contributions — 28% of gross can be 45% of take-home. It also ignores childcare and commuting, either of which can dwarf the difference between 28% and 36%.
Estimate with the rule, then check it against the calculator that models it properly.
Open Mortgage Calculator →Keep housing costs under 28% of gross income, and all debt payments under 36%. The classic mortgage-qualification ratios lenders use.