How to identify a keyboard layout: ISO, ANSI, UK or US

Working out a keyboard's layout means checking three separate layers: the physical shape of the keys, the symbols printed on them and the layout the computer has selected. The checks below cover the Enter and Shift keys, the UK and US symbol positions, the settings in Windows, macOS and Linux, and how to choose keycaps that fit both the board and the legends you need.

Is your keyboard physically ANSI or ISO?

Start with the physical keyboard, because it decides which keycap shapes will fit. Key placement around Enter and the left Shift gives most of the answer. Legends and software settings come after that, and they can contradict the hardware.

Start with the Enter key

The Enter key is the quickest clue. A wide, horizontal Enter key on a single row points to ANSI. A tall, L-shaped Enter key that spans two rows points to ISO. Between these two physical standards, the Enter key makes the difference at a glance.

The shape only tells you about geometry, though. ANSI and ISO describe how the keys are physically arranged. They say nothing about the language printed on the caps or the language selected on the computer.

As a result, an ISO board is not automatically British, because ISO geometry carries many regional arrangements beyond UK English. In the same way, ANSI geometry does not prove the keyboard types US English.

Compare the left Shift and nearby keys

The left Shift key confirms what the Enter key suggests. ANSI keyboards typically have a long left Shift with nothing between it and Z. ISO keyboards typically have a shorter Shift and an extra key in that gap. On a typical UK ISO board, that key carries backslash and pipe. On a typical US ANSI board, backslash sits above Enter instead.

Key sizes are measured in units, where 1u is the width of a letter key. On conventional full-size MX-style boards, an ISO left Shift is 1.25u, while an ANSI left Shift and Enter are 2.25u each. The irregular ISO Enter is commonly described as 2u wide. These figures are examples, not guarantees for every board.

Check compact and laptop keyboards carefully

Counting keys is a tempting shortcut. A conventional full-size keyboard commonly has 104 keys in ANSI and 105 in ISO. Compact and laptop key counts vary, however, so the key count alone cannot settle the question. On a laptop, check the actual Enter and left Shift shapes, the printed legends and the exact regional specification rather than a generic photo of the model family. Then compare the full model or product number with the manufacturer's specifications or service manual.

A number pad tells you nothing either way: its presence does not mean UK legends or ISO geometry. Tenkeyless boards drop it, and 60% boards usually drop the dedicated function row and navigation block as well.

Are the legends and typed symbols UK or US?

Once the geometry is clear, the next question is language. In the UK and US, the key differences are in where the symbols sit, not in the letters, and the printed caps and the selected layout can disagree.

Separate key shapes, legends and output

A keyboard has three layers, and each needs its own check. The UK keyboard layout can be set in software on a board whose shapes and printed caps follow another standard.

• Physical positions: the ANSI or ISO arrangement of keys and switches, which no software setting can change.
• Printed legends: the symbols on the keycaps, which stay the same whatever is selected on the computer.
• Software mapping: the active input layout, which decides which character each key press produces.
• Mixed setups: an ANSI board can carry UK-labelled caps and use a UK input layout while keeping its ANSI shapes.

The letters will not give the answer. UK and American keyboards can both use the QWERTY layout, with the top letter row starting Q, W, E, R, T, Y, even though their symbols and physical format differ.

Read the regional symbol legends

The number row gives the clearest signs. On common PC layouts, Shift+2 types a double quotation mark in the United Kingdom and @ in the US. Shift+3 types the pound sign £ on UK layouts, while US layouts type # on that key.

Other keys help confirm the result. A typical UK board also has a # and ~ key next to Enter. Shift+4 types $ on both layouts, so it cannot tell them apart.

Test what the computer actually types

The printed legends show what the caps say. A typing test shows what the computer does. Open a plain-text editor and type @, the double quotation mark, £, #, backslash and pipe, first without modifiers and then with Shift. Include the keys above 2 and 3, the key beside Enter and the extra key beside left Shift if your board has one.

A printed £ only tells you about the keycap legend. It does not prove ISO geometry or a UK software layout. If the typed character differs from the legend, check the active input layout before you replace any caps.

These positions are common patterns, not rules for every compact, international, remapped or Apple keyboard. Unexpected output can also come from an app-specific input source, a custom keyboard layout, remapping software or keyboard firmware.

Check the selected keyboard layout

The typing test shows the symptom. The operating system shows the cause. Each platform keeps its input settings in a different place, and a layout that is installed is not always the one in use.

Find the active layout in Windows

In Windows 11, open Start → Settings → Time & language → Language & region, then open Language options for your language to see its installed keyboards. In Windows 10, the route is Settings → Time & language → Language. The input indicator on the taskbar shows the active layout, and pressing the Windows key + Spacebar cycles through the installed ones.

Changing keyboard layout starts with Add a keyboard under that language's keyboard options: select the layout, switch to it and test the symbols again. Microsoft Support treats the keyboard layout separately from the Windows display language, so changing the layout does not by itself alter the display language.

Inspect input sources in macOS

On a Mac, go to Apple menu → System Settings → Keyboard → Text Input → Edit to see the enabled input sources. If the Input menu is shown in the menu bar, it names the selected source, and Keyboard Viewer shows the alternate symbols when you hold Shift or Option. The Fn or Globe key may be set to switch sources, so confirm which one is selected before reading anything into a mismatch.

Verify the active source in Linux

On Linux, the keyboard and Input Sources settings depend on the desktop environment and distribution. Check which source is selected and test its output instead of assuming it matches the legends. In GNOME, open Activities, search for Keyboard, review Input Sources and check the active source in the top bar. A layout preview may also be available.

GNOME normally switches to the next input source with Super + Space and back to the previous one with Shift + Super + Space. These shortcuts can be customised, so a key press may have changed the source without you noticing.

Check keycap compatibility before choosing a set

Identifying the layout is only half of choosing a mechanical keycap set. The set has to fit the board's physical shapes and switches, and it also needs to carry the legends you want.

Match the physical caps and switches

A country label on a set is not enough. A replacement set must match the board's key sizes and switch mounts as well as its language legends. A standard ISO board needs three shapes that an ANSI-only set may not include, and ANSI and ISO Enter caps cannot be swapped.

• ISO Enter: an L-shaped cap that spans two rows.
• Short left Shift: the narrower Shift used in the ISO layout.
• Extra key cap: the cap for the key between left Shift and Z.

Check the set's diagram of included keys for Enter, left Shift, the ISO extra key, the spacebar, the bottom-row modifiers and the UK legends you need. Spacebars and modifiers vary from board to board. Sculpted profiles, where each row has its own shape, may also need caps made for specific rows.

Account for non-standard keyboard hardware

The switch decides the mount. MX-style switches use a cross-shaped stem, while low-profile or proprietary switches may need different caps. An ANSI–ISO conversion kit supplies missing cap shapes only if its sizes match the board. It cannot move switches, and the PCB and plate must already support the arrangement you want.

The same caution applies to an unusual compact bottom row or a split spacebar: compare the exact board with its maker's layout diagram. A replacement laptop keyboard must also match the chassis, the connector and the regional variant.

Compare available UK and ANSI sets

With the format and legends confirmed, the choice comes down to coverage. Kromekeycaps offers a range of UK layout keycaps that includes backlit and dual-language options, so you can match UK legends to your board's physical format.

Fit and legends are separate questions. Kromekeycaps sells Standard White & Blue PBT keycaps in US ANSI or ISO versions for 60%, 80% TKL and 100% keyboards. Choosing the ISO version gives you the right cap shapes for an ISO board, not UK symbol legends.

If you need both shapes and UK legends, the White UK Dual Language PBT set comes in US + UK ANSI or ISO versions, with backlit US legends and non-backlit UK legends. It has an OEM profile, a 6.25u spacebar and 104 or 105 caps for Cherry MX-style switches. It is sold without a keyboard.

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