Wiegand bit formats: sixteen layouts across six widths

A bit count does not identify a layout. Sixteen formats share six widths; three split their fields differently, so a number per width is a guess.

The width is not the format

Thirty-four bits is the clearest example. HID H10306 and Honeywell N10002 both use 16 bits of facility code and 16 bits of card number. AWID RS2 spends the same 34 bits as 8 bits of site code and 24 bits of card number. Feed an RS2 card to a decoder that assumes H10306 and it hands back a facility code and a card number that pass every internal check and open nothing.

Thirty-seven bits repeats the pattern inside one vendor: H10302 has no facility code at all — 35 bits of card number — while H10304 splits the same length into 16 bits of facility code and 19 bits of card number. A frame on its own cannot tell you which of the two it is.

Thirty-six bits is worse than ambiguous, because part of it is undocumented. Keyscan C15001 carries a 10-bit OEM code, 8 bits of facility code and 16 bits of card number; Simplex S12906 and AWID 36-bit are different layouts at the same length, and AWID uses its own modulation, so a standard HID-style reader cannot read those cards at all.

Why this site does not do 32, 35 or 37 bit

32 bit has at least five layouts — ATS, generic WIE32, Kantech K32, Nedap, Maxxess — and several carry no parity bits whatsoever, so a corrupted frame cannot be detected and any decoder output is unfalsifiable. Nedap is 16 + 16 with no parity: the same split as H10306 at half the length, which is exactly the trap this table exists to document.

35 bit is HID Corporate 1000: proprietary, with three parity bits interleaved through the data rather than sitting at the ends. Nothing public says where the interleaving starts and stops, so an implementation would be guessing on every frame.

37 bit is not excluded for lack of layouts — H10302 and H10304 are both well attested — but for the parity boundary. Both readings are defensible: Nedap and promptzero/pacs overlap the two 18-bit regions at bit 18, while Suprema starts the odd region at bit 18. Thirty-five data bits cannot be split evenly, and the two answers differ on a bit that appears in both regions. We will add 37-bit support once a public example frame settles it; until then both layouts are listed here as reference only.

Where the numbers come from

Every row is compiled from vendor manuals and third-party documentation, and every row carries a confidence level. High means two or more independent public sources agree and the layout has been checked against a real frame; medium means a single third-party source, or sources that disagree on a detail; low means the field widths are known but the bit positions were not published — do not build hardware around those.

The rows live in one JSON file and this page is generated from it, so a format cannot be added to the table without existing in the data, and a row cannot drift from the data it came from. If a row is wrong, the fix belongs in the data; corrections are genuinely welcome through the contact page.