ANSI or ISO: a layout guide for UK buyers
Updated
ANSI and ISO are the two keyboard layouts on sale in the UK, and it is an easy pair to mix up when buying parts separately: an ANSI keycap set is missing the keys an ISO board needs, and a PCB or plate made for one cannot be turned into the other by a software setting.
This guide sets out the physical differences, why the UK almost always means ISO with a £ key, what that has to do with your operating system's own layout setting, and what it means for buying and building.
Physical differences: Enter, Shift and the extra key
The clearest difference is the Enter key. On ANSI it is a single wide rectangle on one row. On ISO it is a tall, inverted-L shape that reaches up into the row above, where ANSI keeps a backslash key next to a shorter Backspace[2]. To make room for that shape, ISO's left Shift key is shorter than ANSI's, and an extra key appears between Shift and Z that ANSI does not have at all[1].
On a UK board that extra key usually carries backslash and pipe, since the position ANSI uses for backslash (above Enter) is given over to # and ~ instead[2]. None of this is cosmetic: it changes where the plate is cut and how the PCB's matrix is wired, which is why an ANSI-only PCB such as the Geonworks Venom 60 MX PCB cannot become ISO by fitting different keycaps, while a PCB designed to cover both, like the KBDfans DZ60 Rev 3.0 PCB, has the extra pads built in from the start.
This is also why a full-size ANSI board is conventionally described as 104 keys and its ISO equivalent as 105: the extra key, not an extra function row or a bigger numpad, accounts for the difference. Everything outside the main alpha block, the function row, the arrow cluster and the numpad, is identical between the two, which is easy to forget when a listing simply says “104 key” or “105 key” without explaining why.
UK legends and the @ and quote swap
Layout shape is one thing; what is printed on the keys is another. UK ISO keyboards carry a £ symbol (usually Shift-3) and put @ and “ in the opposite positions to a US layout, along with a few other characters moved around[2]. A generic European ISO keycap set is not necessarily a UK one: several ISO markets (Germany, the Nordics, France) each have their own legend layout sharing the same physical shape. The Keychron ISO Cherry Profile Dye-Sub PBT Keycap Set – White Mint is sold as covering UK, German, Spanish, Nordic, French and Swiss ISO boards from one set, which is the sort of thing worth checking explicitly rather than assuming any “ISO” listing means UK legends.
Setting the layout in Windows and macOS
The physical shape of the board (ANSI or ISO) is separate from the software layout your computer applies to each key. Fit an ISO board with the correct Enter and extra key, but leave the operating system on a US software layout, and punctuation will still come out wrong even though the keys are in the right physical place.
On Windows, add the layout under Settings, Time & language, Language & region: add English (United Kingdom) as a preferred language, then check United Kingdom is listed under that language's keyboard options[3]. On macOS, add it under the Apple menu, System Settings, Keyboard, Input Sources, and choose British rather than a generic ISO or European option[4]. Matching the physical board to the right named input source, not just any ISO one, is what gets £, @ and “ typing correctly.
Switching between the US and UK layouts doesn't move any letters, so shortcuts such as copy and paste stay where they were. What changes is which symbol some keys produce, which is exactly the part a UK buyer needs set correctly for £ and the punctuation to land where the keycaps say they should.
Why ISO parts are rarer and cost more
Because ISO needs its own plate cutouts and, on a hot-swap board, its own PCB matrix, manufacturers frequently release ANSI first and ISO later, or not at all. Several hot-swap PCBs in our catalogue make the point on their own: the KBDfans Redux 60 RGB ANSI PCB, KBDfans DZ60RGB-ANSI V2 Hot Swap PCB and KBDfans DZ65RGB V3 Hot Swap PCB are all fixed to ANSI, while ISO support in the same families turns up either on a solder-only board such as the KBDfans DZ60 Rev 3.0 PCB, or on a separate hot-swap PCB made for one specific case, such as the KBDfans Tofu65 3.0 ISO Wired Hotswap PCB, which will not fit anything outside that case.
Keycaps follow the same pattern from the other direction. The PBTfans WoB base kit is ANSI only, and its maker sells ISO coverage as a separate international add-on kit rather than folding it into the base price. Between fewer choices and an extra kit to buy, ISO parts usually end up costing more than their ANSI equivalents for the same board.
Some of that cost is simply extra tooling: a plate needs a different stamping or cutting file for the taller Enter and shorter Shift, and a hot-swap PCB needs its own set of sockets wired in for the extra key, so a manufacturer effectively maintains two products where an ANSI-only one would do. For a small brand or a group-buy run, adding an ISO version at all is a real cost decision, which is part of why it is so often left out or added later as an afterthought.
The builder has an ANSI and ISO toggle, and checks each part you add against the layout you choose, which saves working through catalogue notes like the ones above by hand.