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In order to apply the International Building Code (IBC) requirements correctly, it is sometimes necessary to calculate the occupant load of a room or space.  The IBC defines Occupant Load as:  “The number of persons for which the means of egress of a building or portion thereof is designed.”

The Occupant Load Estimator below can help you to estimate the maximum number of people an area is intended to accommodate.  Here are a few things to consider when using the estimator:

  • Occupant Load Factor:  The factors used in this estimator were taken from the 2021 edition of the IBC.  Refer to the notes at the bottom of this page to determine whether a past edition of the IBC has a variation that applies to your project.
  • Calculation:  For most functions, the occupant load is calculated by dividing the square footage of the space (gross or net as noted in the function field) by the occupant load factor.  For some spaces, the occupant load is not calculated this way.  For these functions, noted in the function field, refer to the referenced code section in the 2021 IBC to learn how to calculate the occupant load.
  • Function of the Space:  Choose the function from the list that most closely matches the use of the space.  The occupant load factor shown for each function will be used to calculate the occupant load.
  • Gross vs. Net:  Note whether the occupant load factor is based on gross or net area, as you will need to enter either the gross or net square footage of the space.
    • Gross floor area is measured within the inside surface of the walls, and includes all occupiable and nonoccupiable spaces. Bathrooms, closets, electrical/mechanical rooms, and other nonoccupiable spaces are not subtracted from the gross floor area.
    • Net floor area is based on the actual occupied area. Nonoccupiable spaces like corridors, stairs, bathrooms, electrical/mechanical rooms, closets, and fixed equipment are subtracted from the total area to determine the net floor area.
  • Decoded: Calculating the Occupant Load: For more information about how to calculate the occupant load, including an example, refer to this Decoded article.


Variations to the occupant load factor tables in past editions of the IBC:

  • 2021 (Table 1004.5) from 2018 (Table 1004.5) – no changes
  • 2018 (Table 1004.5) from 2015 (Table 1004.1.2) – concentrated business use areas, see section 1004.8
  • 2015 (Table 1004.1.2) from 2012 (Table 1004.1.2) – mercantile occupancies, 60 gross SF/person except storage, stock, and shipping areas 300 gross SF/person
  • 2012 (Table 1004.1.2) from 2009 (Table 1004.1.1) – assembly – exhibit gallery and museum, 30 net SF/person
  • 2009 (Table 1004.1.1) from 2006 (Table 1004.1.1) – no changes
  • 2006 (Table 1004.1.1) from 2003 (Table 1004.1.2) – day care, 35 net SF/person
  • 2003 (Table 1004.1.2) from 2000 (Table Table 1003.2.2.2) – no changes


The actual code publications should be consulted when comprehensive data is required and to ensure compliance with the applicable codes.  Accordingly, Allegion and its related companies, subsidiaries, sectors, divisions, and affiliates, and their respective officers, directors, employees, attorneys, agents, successors, and assigns (hereinafter referred to as “Allegion”) make no representations or warranties, express or implied, with respect to the information contained in this resource or output of the estimators, nor does it assume any obligation or liability for any advice provided herein or any reliance upon the estimators by others.