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If you manage access control for almost any building in the United States, there is a good chance your cards and fobs are encoded in the 26-bit H10301 format. It is the original open Wiegand standard, read by nearly every 125 kHz proximity reader ever made, and by far the most common credential format we ship. That ubiquity is also why it is easy to get an order slightly wrong: Two sites can both run "26-bit" credentials and still be completely incompatible because their facility codes or card-number ranges do not match.
This guide explains what the H10301 format is, how the 26 bits are structured, what the facility code & card number mean, which readers & panels accept it, and how to order H10301 cards & fobs that drop into your existing system without reprogramming a thing. Whether you are replacing lost badges, expanding a site, or identifying what you already have, this is the reference page for the standard prox format.
Free samples are available so you can test compatibility before you buy. Request a free H10301 sample card to test on your reader
H10301 is HID Global's designation for the original standard 26-bit Wiegand proximity format. When people say "26-bit," "standard prox," or "open format," they almost always mean H10301. It runs at 125 kHz (low-frequency proximity, not 13.56 MHz smart-card frequency) and it is an open, non-proprietary format — no single manufacturer controls it, and any compliant reader can decode it.
That openness is the whole point. Because H10301 is public, credentials from many suppliers read on the same reader, and readers from many brands accept the same card. It is the lowest-common-denominator format in access control, which is why it became the default for schools, offices, clinics, gyms, multifamily buildings, and light-commercial sites nationwide.
The trade-off is capacity. With only 26 bits, H10301 supports a limited number of unique credentials and carries no encryption. For most everyday access control, that is perfectly acceptable; for high-security or very large deployments, higher-bit and secure formats exist — more on those near the end.
The reason H10301 is called "26-bit" is literal: each credential transmits a 26-bit binary string to the reader. Those 26 bits are divided into four parts:
The two parity bits are not part of the ID you order — they are automatic integrity checks. The leading even-parity bit covers the first 12 data bits, and the trailing odd-parity bit covers the last 12, so the reader can catch a garbled read instead of granting access on bad data. When you order credentials, you specify only the facility code and the card number; the encoding equipment calculates parity for you.
This structure matters for one practical reason: the "number" printed on a card is usually just the card number, but the reader also checks the facility code. Two cards can show the same card number and still be different credentials if their facility codes differ.
Because the facility code occupies 8 bits and the card number occupies 16 bits, the ranges are fixed:
The facility code acts like a "site key": your building is assigned one facility code that every credential at the site shares, while each card carries a unique card number from 0 to 65,535. Your panel is programmed to accept a specific facility code (or a list of them) and a range of card numbers.
Here is the catch that trips up a lot of installers. With only 256 facility codes and 65,536 card numbers, the H10301 pool is finite, and it has been in use for decades. That means the same facility-code-plus-card-number combination physically exists on more than one card somewhere in the world. Within your own site it is unique; globally it is not.
This is why ordering matters so much. To add credentials to an existing system, order cards that continue your existing facility code and fall within an unused card-number range you control. A random "26-bit" card off the shelf may carry a different facility code, or a card number your panel is not programmed to accept, and the reader will simply beep and deny — even though the format is correct. The format being right is necessary but not sufficient; the numbers have to match your system.
This is where H10301 earns its reputation. As the original open standard, it is read by the overwhelming majority of 125 kHz proximity readers in service, regardless of brand. A reader that supports standard 26-bit Wiegand output will accept a compliant H10301 credential.
That broad compatibility includes:
On the panel side, virtually every mainstream access control system understands 26-bit Wiegand, because Wiegand is the data protocol the reader uses to talk to the panel. Controllers from Software House (C-CURE), Lenel, DSX, Keyscan, Kantech, DoorKing, Honeywell, Bosch, and many others accept standard 26-bit natively, with the facility code and card range configured in software.
A few practical notes:
If you inherited a system and are not sure what format it uses, work through these clues:
Still not sure what format you need? Visit our Step-by-Step Guide on How to Identify Your Access Card Format. When in doubt, do not order a large batch on a guess. Confirm the format and your facility code first — a wrong assumption on a 500-card order is expensive.
One of the advantages of the standard prox format is that it is available in every common form factor, so you can match the credential to how people actually carry it. All of the following can be encoded in 26-bit H10301 with your facility code and card range:
Because they share the same H10301 encoding, a single site can mix cards, fobs, and wristbands on the same readers, as long as every credential uses the correct facility code and a valid card number. See the full lineup on the 26-bit H10301 credentials collection, or browse all access cards and fobs if you are comparing formats.
To make sure new credentials work the moment they arrive, provide three things when you order:
If you do not know your facility code or current range, check your access control software or ask whoever administers the system before ordering. Getting these two numbers right is the difference between credentials that badge in on delivery and a box of cards your readers reject. You can also request sequential numbering and matching printed numbers so your team can track credentials easily.
H10301 is the right choice when you need broad compatibility and are matching an existing 26-bit system. But part of ordering correctly is knowing when you are actually on something else:
If you are not certain which of these you have, a free sample test is the safest way to pin it down before a large order. In short: choose H10301 when you are matching an existing standard-prox system and need broad compatibility — the majority of sites; choose a higher-bit, Corporate 1000, proprietary, or smart-card format only when your reader and panel were specified for it.
The surest way to confirm a credential works with your system is to test one on your own reader. A quick sample test verifies both the format and that your facility code and card-number range are set up the way you expect — before you commit to a full batch of cards or fobs.
