Can you direct me to a resource that explains how the maximum occupancy of a commercial building (including different rooms within the building) are calculated?

I have reviewed the information on the NACHI website under "Occupancy Load Signs" which includes a table specifying "Typical Maximum Floor Area Allowances Per Occupant"

however, I have been told that there are other factors involved, such as size & number of exit doors, hallway length, etc.

Your assistance will be greatly appreciated.

Thank you,

Ron Ingber