ISO vs ANSI layout

ANSI is the layout standard common in the United States, with a single-row, rectangular enter key and a wide left shift key. ISO is more common across parts of Europe and elsewhere, with a taller, sometimes L-shaped enter key, a shorter left shift key, and an extra key added next to it, usually for accented characters or additional symbols.

The two layouts are not interchangeable at the keycap or, in some cases, the plate level. An ISO keyboard needs ISO-specific keycaps for the enter and shift row, and some keyboard plates and PCBs are built for only one layout, while others support both with different mounting holes.

Before buying keycaps or a custom keyboard kit, check which layout it is built for, since ANSI keycap sets will not properly cover an ISO board's enter key or extra key, and the reverse is also true. A frequent mistake is buying a full keycap set based on the seller's home country without confirming the actual keyboard layout first.