Rent burden measures what percentage of take-home pay is consumed by housing costs. The widely cited threshold is 30%: households spending more than 30% of net income on rent are considered rent-burdened with limited disposable income for savings, healthcare, and food.

In Lisbon, central rents of ~€1,340/month represent 52% of the median worker's net — well above the stress threshold. In Warsaw, equivalent rents (€820) represent 38% of median net.

Rent burden has risen sharply across all major European cities since 2020 due to post-pandemic urban migration.