How to Use the Egress Corridor & Stair Width Calculator
Egress stairways and corridors need enough width to let everyone evacuate safely during a fire or other emergency, scaled to how many people use the space. This calculator takes your occupant load and component type (stairway or corridor/door) and returns the larger of the occupant-based calculated width and the applicable code minimum as the required width.
It's based on IBC (International Building Code) Table 1005.1, which sets 0.3 inches of width per occupant for stairways and 0.2 inches per occupant for other egress components like corridors and doors. The formula is calculated width (in) = occupant load × per-person factor, combined with the code's absolute minimum widths — 44 inches for stairways and corridors generally, reduced to 36 inches for occupant loads under 50 — with the larger value governing.
Actual code compliance also depends on occupancy classification, sprinkler protection (which can reduce the per-occupant factors under some conditions), number of stories, and whether the space serves as an accessible means of egress. Use this tool for early design checks, and have a licensed architect or fire protection engineer confirm the final egress plan before permitting.
Frequently Asked Questions
IBC Table 1005.1 sets 0.3 inches per occupant for stairways and 0.2 inches per occupant for other egress components such as corridors and doors, without a sprinkler-based reduction applied.
No. This is a minimum life-safety requirement meant to ensure enough time to evacuate during a fire or other emergency, and building below it will be flagged during plan review and inspection.