Keycaps
Profiles, plastics and printing methods, plus how to work out which keycap set will actually fit the keyboard you own.
Keycaps are the only part of a keyboard you actually touch, and the only part anyone else sees. They are also the part most likely to be bought wrongly, because a set that looks perfect can arrive missing four keys your board needs.
This page covers the three decisions that change how a board feels and sounds, profile, plastic and printing, and then the boring compatibility question that causes almost all the regret.
What you are buying
Keycaps are sold in sets, not singly. A set shares a profile, a plastic and a colorway, and is divided into kits.
A base kit covers a standard layout: the letters and numbers, the function row, the common modifiers, and one spacebar. If your keyboard is a normal full-size, tenkeyless, 75 percent, 65 percent or 60 percent board with standard key sizes, a base kit alone will finish it.
Everything else is an extra kit, and this is where sets differ enormously from one another:
- Spacebar kits, because custom boards use different spacebar widths.
- Novelty or accent kits, decorative replacements for escape, enter or the modifiers.
- Extension or 40s kits, for small boards that need key sizes a standard layout does not use.
- Ergo kits, for split and ordered boards like the Ergodox, whose layouts need sizes found nowhere else.
- Numpad kits, sometimes separate even when the base kit covers a full-size board.
- International kits, for ISO layouts and non-Latin legends.
A set that offers only a base kit is fine for a conventional board and useless for an unusual one. Check this before you fall for a colorway.
Sizes, and the unit that runs everything
Keycap widths are measured in u. One u is the width of a letter key, and every other key is a multiple: Tab is 1.5u, Caps Lock is 1.75u, left Shift is 2.25u, the numpad’s tall keys are 2u vertically.
In real dimensions, 1u is 19.05 mm of key spacing, which is three quarters of an inch. The keycap itself is slightly smaller than its spacing so neighbouring keys do not touch, which is why a 1u cap measures about 18 mm across the base.
The number that actually catches people is the spacebar. A standard ANSI board uses 6.25u. A great many custom boards use 7u, and some use 6u or a pair of shorter bars. A set whose base kit includes only a 6.25u spacebar will leave a gap on a 7u board, and there is no way to work around it. Look up your board’s spacebar width before buying anything.
Two other sizes worth knowing because they are quietly incompatible:
- ISO versus ANSI enter. ISO boards use a tall, upside-down L-shaped enter and a shorter left shift. ANSI sets do not include those keys unless they offer an international kit.
- Stepped Caps Lock. Some boards use a caps lock with a raised step. Same 1.75u width, different cap, and only some sets include one.
Wide keys like the spacebar, shift and enter sit on a switch and a stabilizer, so their underside has more than one mounting point.
Profile: the shape
A keycap’s profile is its shape and height, and it changes how a board feels more than most people expect. Two sets in the same plastic with the same legends can feel like different keyboards.
The first division is sculpted against uniform.
Sculpted sets give each row a different height and angle, so the keyboard forms a shallow bowl that your fingers fall into. A row 3 keycap cannot go on row 1; the rows are not interchangeable. This also means you cannot rearrange a sculpted set into an alternative layout like Dvorak or Colemak, because the letters would sit at the wrong angles.
Uniform sets make every key the same shape and height. Any cap goes on any row, which makes them the natural choice for ordered and split boards, and the only sensible choice if you want to rearrange your letters.
The profiles you will actually encounter:
| Profile | Shape | Height | Notes |
|---|---|---|---|
| Cherry | Sculpted | Low | The default of the custom hobby. Most sets you see are this. |
| OEM | Sculpted | Medium | Slightly taller than Cherry. Usually what comes on a prebuilt. |
| KAT | Sculpted | Medium | Slightly deeper dish than Cherry. |
| MT3 | Sculpted | Tall | Deep, heavily scooped, high walls. Divisive and distinctive. |
| SA | Sculpted | Tall | Rounded and retro, noticeably tall. An acquired taste. |
| DSA | Uniform | Low | Spherical dished tops, flat. |
| XDA | Uniform | Low | Flatter and wider top surface than DSA. |
| KAM | Uniform | Low | Cherry-like cylindrical top, uniform height. |
If you have never used anything but a laptop or an office keyboard, Cherry profile will feel normal and anything taller will feel strange for about a week.
Plastic: ABS or PBT
Nearly all keycaps are one of two plastics, and the choice is a genuine trade-off rather than a quality ranking.
ABS takes color better, holds crisp legends, and is the material of choice for doubleshot molding. It is also slightly harder, which gives a higher pitched sound. Its known flaw is that it develops a smooth shine where your fingers land, usually within months. Some people hate this and some consider it patina.
PBT has a faintly textured surface, resists shine almost indefinitely, and sounds deeper and more muted than ABS. Its flaws are narrower color range, a tendency to warp slightly on long keys during manufacture, and legends that are usually less sharp because it cannot be doubleshot as easily.
Thickness matters as much as material. A thick cap of either plastic sounds deeper and feels more solid than a thin one, and cheap stock keycaps are usually thin. If a set lists its wall thickness, anything at or above 1.4 mm is substantial.
POM appears occasionally: slippery, dense, and distinctly deep sounding. Rare and expensive.
Printing: how the legends got there
This decides whether your legends will still be there in five years.
Doubleshot molds the cap twice, once for the body and once for the legend, so the letter is a separate piece of plastic all the way through. It cannot wear off. It is the best method, and the reason GMK’s ABS sets dominate the hobby.
Dye sublimation dyes the legend into the surface of the plastic with heat, so it is chemically part of the cap rather than sitting on top. Also permanent, and the standard for PBT, since PBT resists doubleshot molding. It cannot print a light legend onto a dark cap, which is why dye-subbed sets are usually dark text on a light cap.
Reverse dye sublimation dyes everything except the legend, which is how you get a light legend on a dark PBT cap. More difficult, and the reason those sets cost more.
Pad printing presses ink onto the finished cap with a rubber pad. Cheap, and it wears off. If a budget set has legends that feel slightly raised, this is why.
Laser etching burns the legend into a coated cap, usually to let backlighting through. Durable, limited to what a laser can cut.
UV printing lays ink on the surface and cures it with ultraviolet light. Allows photographic detail and full color, and sits on top of the cap rather than in it, so it can wear.
And blanks, which have no legends at all. Cheaper, cleaner looking, and entirely fine if you can type.
Reading a keyset name
Set names follow a pattern: manufacturer or profile, then the design name.
- GMK Future Funk. GMK is a German manufacturer that makes ABS doubleshot caps in Cherry profile, so the name tells you the plastic, the printing and the profile before you read anything else.
- ePBT Kuro. ePBT makes PBT dye-sub caps in Cherry profile.
- KAT Drifter. KAT is a profile, made by Keyreative, in PBT.
- MT3 Susuwatari. MT3 is a profile, so the name tells you the shape and nothing else.
Common abbreviations: WoB is white legends on black caps, BoW is black on white, and R2 means a second production run of a set that sold out.
Buying without getting it wrong
In order:
- Find your board’s layout and spacebar width. This is the step people skip. A 7u spacebar board and a 6.25u-only set is an unfixable mismatch.
- Check the kit list, not the render. The photograph shows every kit assembled. Work out which kits you need and price those.
- Decide sculpted or uniform. Sculpted unless you have a split or ordered board, or you want to rearrange the letters.
- Pick the plastic on the shine question. If a worn sheen would annoy you, buy PBT. If crisp color matters more, buy ABS.
- Check the printing method. Doubleshot or dye-sub for anything you intend to keep. Pad printed legends will not last.
- Check whether it is in stock. Many sets are group buys and will arrive in a year, not a week.
Changing keycaps needs no tools beyond a puller, takes ten minutes, and is completely reversible, which makes it the cheapest way to change how a keyboard sounds and the easiest thing to experiment with. Just buy the right sizes.