Occupancy Load Calculator
Calculate a building or room's occupant load from its floor area and the IBC occupant load factor for its use, for egress and code planning.
How this calculator works
An occupant load answers a simple question: how many people can this space hold, according to code? The building code doesn’t ask you to guess — it assigns every use type a fixed number of square feet per person, and you divide your floor area by that number.
The result feeds directly into egress design, since the number of required exits and their combined width both scale with how many people the space is expected to hold.
Formula: Occupant load = floor area ÷ occupant load factor (square feet per person, from IBC Table 1004.5, which varies by use — for example business use ≈ 150 sq ft/person gross, assembly standing ≈ 5 sq ft/person, with many common uses falling in the 15–100 range).
Worked example
A 3,000 sq ft space with an occupant load factor of 15 sq ft per person (a common assembly/mercantile-adjacent factor):
- 3,000 ÷ 15 = 200 occupants
Notes
The occupant load factor depends entirely on the space’s IBC use classification. Assembly spaces with fixed seating, standing assembly areas, business offices, and storage spaces all carry very different factors, and using the wrong one changes the number of exits and the exit width your code review requires.
Always confirm the correct factor for your specific occupancy classification in IBC Table 1004.5 or with your local building department before finalizing egress plans.
How to use
Enter your space’s floor area in square feet and the occupant load factor that matches its IBC use classification. The calculator divides the two to return the occupant load — the number your egress and code planning is built around.
This is a planning estimate using a simplified version of the standard code formula, not a substitute for engineering design. Confirm actual load values and code compliance with a licensed structural engineer.
Frequently asked questions
What is an occupant load factor?
An occupant load factor is the square footage the building code assigns to one person for a given use, from IBC Table 1004.5. It ranges widely — a standing assembly space might use around 5 sq ft per person, while a business office might use around 150 sq ft per person gross — because different uses pack people at very different densities.
How does occupant load affect exit requirements?
Occupant load drives how many exits a space needs and how wide they must be, since code sizes egress capacity to the number of people who could be inside at once. A higher occupant load generally means more exits or wider exit doors and corridors, so getting the load factor right matters directly for code compliance.
Why does the occupant load factor vary so much between uses?
Different activities pack people at different densities. A standing assembly area like a dance floor holds people much more tightly than a business office full of desks and equipment, so the code assigns each use type its own square-footage-per-person factor rather than one blanket number for every building.
How do I find the correct occupant load factor for my space?
Identify your space's IBC use classification — assembly, business, mercantile, storage, and others each have distinct factors — and look up that classification in IBC Table 1004.5. Your local building department can also confirm the correct classification and factor for your specific space before you rely on any occupant load number.
Estimates only. Verify quantities with your supplier before purchasing.