The site or facility code is a number that represents the facility or building. This number will be the same for all employees at a single location. You may see Facility Code abbreviated as FC and some companies use the term Site Code.

With a 26 bit card, the number must be between the range of 0 and 255 characters. Some access control systems allow multiple facility codes to accommodate companies with more than one location. (26 bit cards are also known as H10301 cards.)

With a 37 bit card, it is likewise an open code format but this alternative format contains more than 2,000 times as many individual codes, decreasing the likelihood of duplicate cards. Like the 26 bit format, is it is offered at no additional cost. This 37-bit format must be programmed into the host system by the installer in the first use of this format on that system. (37 bit cards are also known as H10302 cards.)