Navigating the World of HID 37-bit Card Formats – H10304 and H10302

Navigating the World of HID 37-bit Card Formats – H10304 and H10302

by Mike Boehm on January 23, 2024

In the realm of RFID credentials, it can sometimes be confusing trying to distinguish between seemingly similar cards. The two 37-bit cards – the H10304 and the H10302 – are a perfect example of this. What does 37-bit mean? And what is the actual difference between these cards? Continue reading to learn the answers to these questions, plus where to find affordable, high-quality H10302 and H10304 cards!


37-bit Format

A 37-bit card format means that each card’s data is stored in a string of 37 bits. These bits are binary digits, each being either a 0 or a 1. The way these bits are divided and used can vary, especially when it comes to including a facility code.


Parity Bits

Thirty-seven bits can be divided up in different ways, which is exactly what was done with the H10304 and H10302 card formats. Both cards include two parity bits as a form of data error checking. When the card is swiped or read, the system checks the parity bits to ensure that the data has not been corrupted or altered during transmission.


Facility Codes

Some formats use facility codes, which offer a meticulous allocation of access rights. Facility codes are unique numerical identifiers assigned to specific locations or departments. 

For instance, an employee affiliated with Site A, whose credentials are embedded with the Site A facility code, would be unable to access Site B using their ID card. This restriction ensures a stringent security protocol, preventing unauthorized entry across different sites. 

Similarly, facility codes can be employed to safeguard specific sections within a building. Take a scenario where a particular area is designated solely for the Human Resources department; access can be exclusively reserved for individuals with the appropriate facility code.


Cardholder ID

The Cardholder ID is a unique numerical identifier assigned to each individual cardholder. The range of values that a Cardholder ID can take is determined by the number of bits allocated to it. For example, if 19 bits are used for the Cardholder ID, it can take values ranging from 0 to 2^19 - 1, which is 0 to 524,287.


HID 37-bit H10302 – Open Format

The 37-bit H10302 cards are a more accessible solution that is available to all customers. As open format cards, the H10302 is available from a number of different third-party providers, which means you can shop around to find affordable generic cards. 

  • Parity Bits – 2 parity bits for added security and data integrity. 
  • No Facility Code – Does not dedicate any bits to a facility code. This leaves more bits available for unique identifiers. 
  • Cardholder ID – A 35-bit Cardholder ID field offers a unique number for each and every card imaginable (ranging between 0 and 34,359,738,367). 
  • Potential Duplicates – Because H10302 is an open format, it’s possible for duplicate ID numbers, although unlikely, given the large range of possibilities. 
  • Accessible – The H10302 can be used by anyone with a 37-bit access control system, including HID ProxPoint, MiniProx, Thinline, ProxPro, MaxiPro, and EntryProx readers. 


HID 37-bit H10304 – Proprietary Format

The 37-bit H10304 cards differ from H10302 cards in that rather than having a range of id numbers above 34 million, H10304 cards only have a range of around 524 thousand.  The benefit of the H10304 format is that you can also utilize facility codes between 0 and 65,545.  That's important to many companies as they can now use facility codes to restrict access in various creative ways.

  • Parity Bits – 2 parity bits for added security and data integrity. 
  • Facility Code – Uses a 16-bit Facility Code, which offers a huge array of identifiers for different facilities or departments (ranging between 0 and 65,545). 
  • Cardholder ID – A 19-bit Cardholder ID field ensures a unique number for each and every card (ranging between 0 to 524,287). 
  • Exclusive – Offers an additional layer of security since all cards are guaranteed unique by HID. 
  • Ideal for Large Organizations – With a large number of sites, departments, and employees that need secure access, no other organization’s cards will randomly work at your locations.


Where to Purchase Credentials?

AuthorizID has a variety of H10304 credentials like cards, key fobs, adhesive tags and wristbands. You can find all our 37 bit H10304 solutions here.

We have printable cards and clamshell cards that will work with a wide range of HID readers, including HID ProxPoint, MiniProx, Thinline, ProxPro, MaxiPro, and EntryProx. Click here to see all our H10302 options.

 If you want to test our 37-bit H10302 cards out before committing to a larger order, we can get you set up with a free sample! Our team is on standby 24/7 at (970) 682-0765 or via email at, ready to assist you with any inquiries or to help you navigate through your options to find the perfect solution.

Want to request a free sample card to test?