Egress Width Calculator

Required egress widths per floor. Stair load accumulates automatically as you go down the building.
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Building Settings

Sprinkler System

Exits per Floor

Exits are the ways people leave each floor — stair doors, exterior doors at grade, horizontal exits.

This sets how wide each door and corridor needs to be. The floor's occupant load is split evenly between the exits.

Example: a floor with 2 stair doors = 2 exits.

IBC Table 1006.3.3 requires:
OL 1–500 → min. 2 exits
OL 501–1,000 → min. 3 exits
OL > 1,000 → min. 4 exits

Stair Enclosures

Stair enclosures are the vertical shafts connecting floors — the actual stairwells.

As people enter each stair on their way down, the load accumulates. More enclosures = the cumulative load splits between more stairs.

Above-grade and below-grade stairs are separate enclosures — a basement stair doesn't carry the load from upper floors. (IBC §1023.1)

Stairs onto Discharge

Stairs discharging onto the level — when a stair enclosure empties into a lobby or corridor at the exit discharge level instead of directly to the exterior.

People from those stairs become additional load on that floor's doors and corridors.

IBC §1028.1 limits: No more than 50% of the number and minimum width of exit enclosures can discharge through the level of exit discharge.

Fire rating required: The exit discharge path on that floor must be separated from the rest of the floor by construction rated at least equal to the stair enclosure rating (1 hr ≤4 stories, 2 hr >4 stories per §1023.2). Entire level must be sprinklered.

Floors

List floors top to bottom. Click ★ to mark exit discharge level. Everything above accumulates down the stair. Everything below accumulates up independently.

★ Label Occupant Load

Required Widths by Floor

Revit Text Output

Egress width calculations per IBC Section 1005.1, Table 1005.1. Minimum component widths per IBC 1010.1.1 (doors), 1011.2 (stairways), 1020.2 (corridors). Stair convergence per IBC 1005.1. Above-grade and below-grade stair enclosures independent per IBC 1023.1. Exit discharge through level per IBC 1028.1. Minimum number of exits per IBC Table 1006.3.3. This tool does not determine travel distance, common path of travel, or exit separation distance. Green Stories LLC is a building design and consulting firm. All projects requiring a licensed architect are completed in collaboration with registered design professionals.