The Complete Wiegand Format Guide

Wiegand the wiring protocol vs Wiegand the data format

The original Wiegand effect describes specially treated wires that produce a sharp magnetic pulse, and that effect gave its name to a reader interface that signals a controller over two data lines, D0 (data-zero) and D1 (data-one), plus ground. That interface is the wiring protocol. It only carries a stream of ones and zeros and says nothing about what those bits mean.

The Wiegand data format is the agreement about what the bit stream means: how long it is, which bits are the facility code, which are the card number, and which are parity. Two readers can use the identical 5-volt D0/D1 wiring yet present completely different formats. When someone says a card is '26-bit Wiegand' or '37-bit H10304', they are describing the data format, not the cable. Modern 13.56 MHz credentials built on genuine NXP MIFARE silicon, as well as iCLASS credentials, often still carry a Wiegand-format payload internally so they drop into existing panels, even though no physical Wiegand wires are involved.

What is inside a Wiegand format: facility code, card number, and parity

Almost every Wiegand format is built from three ingredients. The facility code (also called a site code or, on some HID formats, a company or customer code) identifies the organization or installation. The card number is the unique credential ID within that facility. Parity bits are error-checking bits the reader computes over defined ranges of the data so the panel can reject a garbled read.

The classic 26-bit H10301 is the textbook example: 1 leading parity bit, an 8-bit facility code (0-255), a 16-bit card number (0-65,535), and 1 trailing parity bit, for 26 bits total. The leading bit is even parity over the first 12 data bits; the trailing bit is odd parity over the last 12 data bits. Larger formats simply widen the facility-code and card-number fields and adjust the parity scheme, which is why a 35-bit Corporate 1000 can address far more cards than a 26-bit format ever could.

• Facility / site / company code: identifies the building or organization
• Card number: the unique holder ID within that facility
• Parity bit(s): error checking computed over fixed bit ranges
• Total bit length: the headline number (26, 34, 35, 37, 48, and so on)

What are the common Wiegand bit formats?

The 26-bit H10301 is the most widely deployed format in the world. It is an open, non-proprietary industry standard: any manufacturer may produce it, the field widths are public, and that openness is exactly why it is the easiest to match. The trade-off is a small address space, only 256 facility codes and about 65,000 card numbers, so the same facility-code/card-number pairs recur across unrelated sites.

Above 26 bits sit the wider HID formats. The 34-bit H10306 carries a 16-bit facility code and a 16-bit card number; the 37-bit H10304 carries a 16-bit facility code and a 19-bit card number; and the related 37-bit H10302 drops the facility code entirely in favor of a single 35-bit card number. These give far more headroom than 26-bit while remaining standard published formats.

HID Corporate 1000 is a registered, managed program. The 35-bit C1000 uses a 12-bit company/facility ID plus a 20-bit card number; the 48-bit C1000 expands the company code and uses a roughly 23-bit card number, supporting millions of unique credentials. Corporate 1000 formats and their card-number ranges are controlled by HID for an enrolled customer, which is why the issuing organization, not a card supplier, owns the numbering.

Finally, many access platforms ship proprietary formats of unusual lengths, such as a Software House CCOTZ 37-bit, a Lenel 42-bit, an Avigilon 56-bit, or DMP 31/33-bit. These rearrange the facility-code, card-number, and parity fields in vendor-specific ways. They still ride the same Wiegand interface, but you have to match the exact format, not just the bit length. These are the specialist formats most suppliers don't stock, and they are exactly where our format expertise is strongest.

Why facility-code matching is the whole ballgame for a compatible card

A controller does not just check that a card is the right format and length. It checks the values inside, and the facility code is the gatekeeper. Most panels are programmed to admit only credentials whose facility code matches the one configured for that door or system. A card with the correct bit format but the wrong facility code reads fine at the reader and is then rejected by the panel, which looks identical to a 'bad card' even though the encoding is technically valid.

That is why ordering a compatible card means supplying three things: the format (for example 26-bit H10301), the facility code, and the card number or a range. Get the format right but the facility code wrong and nothing opens. The facility code and card number are usually printed on your existing cards or available from your access-control administrator, and they are the details that let us encode a compatible credential that presents the exact data your readers already accept on an open format, identical to your originals.

• Tell us the format name or bit length (e.g. 37-bit H10304)
• Tell us the facility / site / company code
• Tell us the card number or the range you need encoded

Which Wiegand formats can be supplied on a compatible card?

Open low-frequency Wiegand formats reproduce cleanly. 125 kHz HID Prox, Indala, AWID and similar credentials carry their Wiegand payload as an open, non-proprietary signal, so we can encode that exact format, facility code and card number onto a programmable T5577 or compatible blank that the reader treats as identical to the original. Open legacy 13.56 MHz credentials that simply present a Wiegand payload can be matched the same way.

Registered and proprietary formats work differently. HID Corporate 1000 numbering is managed by HID for the enrolled customer, so supplying matching cards depends on the customer's own program access. And secured smart credentials, MIFARE DESFire with AES, HID Seos, and iCLASS SE or Elite, are secured by design. For those we supply compatible blank credentials on the matching chip platform; your own system or integrator enrols them with its keys, exactly as it would credentials ordered through the OEM channel, so the keys and your site security stay in your hands. We are an independent manufacturer and supplier of compatible access-control credentials and are not affiliated with, authorized by, or endorsed by HID, Lenel, Software House, or any other manufacturer.