When you are starting a business, one of the most important numbers is the maximum occupancy of the room you will use for your business. That's the largest number of people the local fire department will allow in the room at one time. This number is especially important for businesses such as bars, restaurants and theaters. Only the fire department can give you a definitive number, and that will depend on a wide variety of factors, including emergency exits, columns, furniture placement, etc. But you can estimate maximum occupancy if you know the dimensions of the room.
Measurements
Measure the width and length of the room. Measure only the area where people will sit or stand; for example, if you want to find the maximum occupancy of a bar, measure only where patrons will stand, and not the area behind the bar. If you have a room that is shaped irregularly, separate the room into square portions for ease of measurement.
Read More: International Building Code Occupancy Loads
Figure the area of the room, by multiplying the length by the width. For example, if your room is 50 feet long and 40 feet wide, the area is 2,000 square feet (50 x 40 = 2,000). If you measured the room in sections, add up the square feet of each section.
Divide the square footage by 36. In the example above, divide 2,000 by 36 to get 55.55. Rounding down--the safer bet, since the fire marshal will always play it safe by allowing a smaller maximum occupancy-- that room should be able to hold 55 people. However, the occupancy will be lower if there are a number of obstructions, such as tables, columns or couches.