Building occupancy fire codes are a very important way to ensure that people can exit a building safely in case of an emergency. There are a number of factors that go into determining the capacity of a building. One of the most important factors is the size of the floor space of the room. Other factors include the type of doors, the way the room itself is laid out, the furniture configuration in the room and the typical use of the room.
Measure the room. If the room is rectangular, measure two walls and multiply the figures together to get the square footage of the room.
Take out the calculator to calculate room capacity based on size. If the room is larger than 10,000 square feet, divide the room size by 7 to get the general number of people who can fit into that space. According to the Life Safety Code, the number of occupants should not be greater than one person per 7 square feet.
If the room is smaller than 10,000 square feet, divide the room size by 5 to get the general number of people who can fit into that space. In a smaller room, the number of occupants should not be greater than one person per 5 square feet.
Assess the space to determine other factors that may reduce the number of people who should be in a space at one time. Factors to look for include doors that are difficult to open or only accommodate a limited number of people at one time, a room that is designed with a single exit that is hard to reach from some corners and seating arrangements that are hard to get around such as large tables and bleachers. The behaviour of people on the premises is also important---for example, dancing in a small space at a club or the presence of potentially flammable materials in a store would both increase risk.
Refer to the U.S. National Fire Code when formally assessing a space for occupancy numbers. You can find this code for sale from the National Fire Protection Association. It is important to have a professional formally inspect your space for potential dangers.