How to calculate the load of a building

Occupant load describes the number of square feet assigned to each person inside a building. The calculation of occupant load depends on the density of people anticipated for a particular area, depending on their use. It is calculated differently for different parts of a building or different types of establishments. You can use the National Fire Protection Association’s Life Safety Code as a frame of reference when calculating the expected occupant load for a building. This can be increased if the number of outputs in the area increases.


  1. Calculate the net area of ​​the building. For example, the area below storage sites and large objects such as pool tables must be subtracted from the gross area of ​​the building to calculate the net area.
  2. Calculate the expected number of occupants for different areas of the building. For example, if the building will be a school, count the number of students expected to sit in the auditorium.
  3. Check the National Fire Protection Association’s Life Safety Code to determine how many people are recommended per square foot for each sector of the building based on anticipated use of the same. Divide the net area of ​​the building by the recommended number of people per square foot to get the value of the expected occupant load.