Occupant Load Calculator
The occupant load of a floor from its area and use — the number every fire and egress calculation starts from — and the total exit width and number of exits it needs.
Codes assign each use a floor area per person: about 10 m² for offices, 1 to 2 for assembly, 30 for warehouses.
How the occupant load calculator works
Codes assign each use a floor area per person: about 10 m² for offices, 1 to 2 for assembly, 30 for warehouses. Divide the area by that factor and you have the occupant load the exits must serve.
Exit width follows: a set number of millimetres per person, with a minimum count of exits above a load threshold. The factors here are common defaults and inputs, because every code sets its own.
Formula: occupants = area / factor; exit width = occupants × mm per person
Worked examples
| Inputs | Occupant load | Note |
|---|---|---|
| A 1,400 m² office floor | 140 | 140 people, two exits |
| A function room | 267 | 267 people from a small floor |
| A warehouse | 134 | few people, wide floor |
FAQFrequently asked questions
What is occupant load?
The number of people a space is designed to hold for fire and egress purposes — floor area divided by a factor set by the use. It is often higher than the number who will ever be there.
What area per person applies?
About 10 m² for offices, 1 to 2 for assembly and bars, 3 for shops, 30 for storage. Every code publishes its own table; the default here is the office figure.
How much exit width per person?
Ten millimetres is a common figure for a level exit; stairs need more. Codes also set minimum door and corridor widths regardless of load.
When are two exits required?
Above a load threshold — often 50 — or above a travel distance. Larger loads need three or four. The count here is a common default, not your code.
Can I reduce the occupant load?
By declaring a lower design occupancy and posting it, in some codes. The exits still need to serve whoever actually turns up.
Where these figures come from
- Sabine (1922) — Collected Papers on Acoustics — the reverberation-time equation
- CIBSE Guide A — Environmental design — daylight, comfort and ventilation criteria
- Neufert — Architects' Data — the standard reference for space and dimension
- International Code Council — International Building Code — occupant load and egress factors
- Building Regulations — Approved Documents — the UK building regulations
Last checked: September 2026. Formulas are the standard building-science and code relationships; default thresholds are common international values and should be replaced with the ones in your code.