A room's occupancy load is calculated by dividing the square feet of a room by the number of square feet each individual person needs, according to International Association of Home Inspectors. Such needs depend on the setup and function of the room, and there are set values for such measures.
The number of square feet needed per person is set by a building's designer in keeping with code regulations that prescribe such values, reports the International Association of Home Inspectors. These values can differ widely. For instance, in an assembly area such as a bar or restaurant, if there are no chairs or tables, each person needs at least 5 square feet of space. So a room that is 5,000 square feet with standing room only, such as a club or concert venue, has a maximum occupancy of 1,000 people. If there are tables and chairs in the same room, such as if it is used as a dinner club, each person needs at least 15 square feet of space, so the maximum occupancy is 333 people.
Other areas commonly require considerably more square feet per person, and the maximum occupancy has to be adjusted, explains the International Association of Home Inspector. For instance, a gym that is 5,000 square feet generally has a maximum occupancy of 100 people, because each person needs at least 50 square feet of space in that environment.