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Occupant Load & Exit Width Calculator

Calculate the occupant load of a room or floor from area and the IBC/NFPA 101 occupant load factor, the number of exits required, the total egress width for doors and stairs (0.2 and 0.3 inch per person), the capacity of your existing doors and whether a sprinkler system changes the numbers.

Floor area

Occupancy / use

Building sprinklered with voice/alarm?

Existing exit doors

Clear width per door

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How it works

Occupant load = area ÷ load factor (rounded up); exits: 1 (≤ 49), 2 (≤ 500), 3 (≤ 1,000), 4 (> 1,000); door width = load × 0.2″ (0.15″ sprinklered); stair width = load × 0.3″ (0.2″ sprinklered)

Building codes size exits for the number of people a space could hold, not the number who happen to use it, so every use has a load factor in square feet per person — five for a standing crowd, fifteen for a restaurant, one hundred and fifty for offices. Dividing area by the factor gives the occupant load, which fixes how many exits are needed, how wide they must be in total (a fifth of an inch of clear door width per person, three tenths for stairs, reduced where sprinklers and voice alarm buy time), whether doors need panic hardware and outward swing, and what maximum occupancy is posted on the wall. Gross factors use the whole floor; net factors use only the occupiable area, excluding corridors, restrooms and mechanical rooms.

Worked example

A 3,000 ft² banquet room with tables and chairs holds 200 people. It needs two exits, 30″ of total door width in a sprinklered building (40″ unsprinklered) and 40″ of stair width; two 32″ doors give 64″ — capacity 426 — so they are adequate, and panic hardware is required because the assembly load exceeds 49.

Frequently asked questions

Gross versus net floor area?

Gross is the whole floor within the exterior walls. Net excludes non-occupiable spaces — corridors, stairs, toilets, closets, mechanical rooms and, in assembly, the stage and fixed equipment — so net factors apply to a smaller area.

Can the posted occupancy be higher than the calculation?

The code official may approve a higher load if the egress system is shown to accommodate it and the density does not fall below 7 ft² per person; more usually, exit width or the number of exits limits the room below the raw calculation.

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Load factors and width per occupant follow the International Building Code (2021) and NFPA 101 in general terms; jurisdictions amend them and many special cases (fixed seating, mezzanines, accessory areas, travel distance, common path) are not covered. A code consultant or the building official confirms the design.