Are Keycaps Universal? (And Which Ones Are Not?)

You found the set. Right color, right profile, in stock. Then you stop, because a small voice asks whether it will actually fit your keyboard.

Most of the time it will. Mechanical keyboards settled on one mounting standard decades ago, and that standard is why you can buy keycaps from a shop that has no idea which board you own. The standard has holes, though, and they turn up in places people don't expect: an old Logitech, a Realforce, the thin keyboard in your backpack.

Below is what makes keycaps interchangeable, the three checks that answer nearly every fit question, and the switch families that ignore the standard entirely.

The short answer

Why most keycaps fit: the MX cross stem

Cherry put a cross shaped stem on top of the MX switch back in the 1980s. Keycaps mount by pressing onto that plastic "+" sign, giving you a friction fit that holds up over tens of thousands of keystrokes. 

When the patents ran out, every company that copied Cherry copied the plus sign too instead of designing something new. Gateron, Kailh, TTC, Outemu, Akko and a long list of others all went with the same mount. That is the only reason an aftermarket exists at all. Nobody has to know what board you own, because the mount is identical on a cheap prebuilt and an expensive custom keycap.

The catch is that the cross stem is a standard, though, not a law. Several switch families never signed up.

Three things to check before you buy

Fit problems come from three places: the mount, the width of the keys, and the height of the caps. 

1. The stem

Pull a cap off. Esc is the easiest. Then look at the switch underneath.

A plus sign means MX, and you are almost certainly fine. A rectangle, a round post, a ring, or two separate prongs means you're in specialty territory. See the list below.

2. Layout and key sizes

A keycap can mount perfectly and still be the wrong key, because the bottom row is where manufacturers do whatever they like.

Keyboards measure key widths in "u" units, where 1u is the width of a standard letter key. Most of a keyboard is standardized, but the bottom row is a free-for-all:

• Standard ANSI bottom row: 1.25u modifiers either side of a 6.25u spacebar.

• Gaming-brand bottom rows: Corsair (and older Logitech/Razer boards) often use a 6.5u or 6u spacebar with wider and narrower modifiers to match. A standard kit simply won't fill it.

• ISO layout (common in Europe): taller, L-shaped Enter, a 1.75u left shift instead of 2.25u, and an extra key squeezed next to the spacebar. 

Also worth a look: stepped Caps Lock, where a single cap has two heights, on some Cherry and Unicomp boards. Split spacebars on ergo and 40% layouts. And the odd modifier sizes on HHKB, Planck, and Alice boards.

For European language users, changing keycap language to another European language is possible. To learn more about changing language, please visit our guide on changing keyboard language.

3. Profile

Profile means the height and sculpting of the cap, and common keycap profiles include Cherry, OEM, SA, DSA, XDA, KAT, MT3 and others. All of them mount on an MX stem, so profile is never a mounting problem, but it can still be a fitting problem.

• Switch orientation. If your switches are North-facing switches (with LEDs positioned at the upper part of the switches), they may not be very compatible with Cherry Profile keycaps, making the keycaps hit the edge of the switches when being pressed down, causing a mushy feel.

• Row sculpting. Sculpted profiles have different shapes per row (R1–R4). Install them in the wrong row and the keyboard feels wrong even though every cap "fits." Uniform profiles like DSA and XDA sidestep this entirely, which is why beginners often prefer them.

To learn more about factors to consider when buying keycaps, please visit our keycaps buying guide

Switches that won't take standard keycaps

Here is a list of a common switch type and their compatibility with standard keycaps (MX-style keycaps).

Switch type	What the stem looks like	Standard keycaps?	Commonly found in
Cherry MX and clones (Gateron, Kailh, TTC, Outemu, Akko…)	"+" cross	Yes	Most mechanical keyboards
Hall effect / magnetic (Wooting Lekker, Gateron KS-37B, Keychron Super)	"+" cross	Yes	High-end gaming keyboards
Optical switches (Razer Opto, Gateron Optical)	"+" cross	Yes	Razer, E-Yooso, various gaming boards
Kailh BOX	Thicker "+" cross	Yes, but may stretch ABS caps	Some prebuilts and budget customs
Cherry MX Low Profile	"+" cross (shorter travel)	Yes, but will make the keyboard thicker if use standard Cherry profile or other taller profile keycaps	Thin mechanical keyboards
Topre / electrostatic capacitive	Round slider, no cross	No	HHKB, Realforce, Niz, Leopold FC660C/980C
Alps and Alps clones (Matias, SMK, Omron B3G-S)	Rectangular box mount	No	Vintage Apple boards, Matias keyboards
Logitech Romer-G	Hollow ring with cross shoulders	No	Older Logitech G-series
Logitech GL (low profile)	Kailh GL, Choc-style	No	Logitech G815, G915
Kailh Choc v1 / v2	Two-prong low-profile stem	No	NuPhy, Keychron low-profile, many portable boards
Cherry ML / MX Ultra Low Profile	Proprietary	No	Ultra-thin keyboards, some ThinkPad boards
IBM buckling spring	Integral barrel, cap and stem are one part	No	IBM Model M / Model F, Unicomp
Membrane / scissor / chiclet	No standard stem	No	Office keyboards, laptops

Topre and other electrostatic capacitive

There is no stem on a Topre board. The cap slides onto a round cylindrical slider above a rubber dome and a capacitive cone, so an MX cross has nothing to grip. HHKB, Realforce, Niz, and the Leopold FC660C and 980C all work this way.

People do sell MX slider conversion kits for some Topre boards. You swap the sliders and the board takes normal caps. It is a full teardown rather than a Sunday afternoon job, but the option exists.

Alps and its clones

Alps uses a rectangular mount with a notch, and Alps mount caps are still made, just by fewer vendors than MX. Matias still sells Alps style switches today, so a Matias board needs Alps caps. Most vintage boards from the 80s and early 90s sit in this family too, including the Apple Extended keyboards that turn up in thrift stores.

One warning: The Alps mount looks close enough to MX that people try to force it. Don't. You will split the keycap or crack the switch housing.

Logitech Romer-G

Romer-G, the switch Logitech built with Omron, has a hollow ring with cross shaped shoulders. MX keycaps will not sit on it. The G910, G810, G613 and similar older G series boards are the ones that catch people out, and this is probably the most common "my new keycaps don't fit" story in the hobby.

The confusing part is that even if the same model, there will be Romer-G version and GX switches version (MX-style cross), so please check the stems before buying replacement keycaps.

Low-profile switches

Low-profile is where compatibility gets messy, because there is no single standard:

• Kailh Choc (v1 and v2), Cherry ML, and Logitech GL all use proprietary stems. Standard caps will not fit.

• Cherry MX Low Profile and some newer Gateron low-profile switches do use a standard MX cross, so keycaps mount fine.

Even when the stem works, low-profile boards have tighter key spacing, so a tall sculpted set can look and feel wrong. When in doubt, check the switch spec sheet rather than assuming.

Buckling spring

On an IBM Model M (and Model F, and modern Unicomp reissues), the keycap and the spring barrel are effectively one assembly. There's no separate stem to mount onto. Unicomp does sell replacement caps for its own boards, but you're not putting a PBT double-shot set on a Model M.

Membrane, scissor, and laptop keyboards

If there's no discrete switch under each key, there's nothing to mount a keycap on. This covers every rubber dome office keyboard, every scissor-switch laptop, and Apple's Magic Keyboard. No aftermarket set will fit, and no amount of force will change that.

What can I do If my switches are not MX-style

If your keyboard switches are not MX-style cross switches, your keycap options may be limited, but there are still some choices. First off, if you only want to replace your worn out or broken keycaps, you can try to find replacement keycaps from original manufacturer or third party sellers. At KeycapGuru, we provide replacement keycaps for some specific keyboard models, including non-MX ones like Logitech G915 and G910.

If you want to use a custom MX keycap on your non-MX keyboard, then you may want to convert the keyboard switches to MX-style first. We are working on converters to convert non-MX switches to MX, and currently we can convert Logitech GL switches and Romer-G switches. More keycaps and converters will come in the future.

FAQ

Do all mechanical keyboards use MX stems? No — most do, but not all. Alps, Topre, Romer-G, and most low-profile switches use different mounts. Check the stem before assuming.

Can I put custom keycaps on a Logitech keyboard?

It depends on the switch. Newer Logitech keyboards using GX switches take standard MX keycaps. Older ones with Romer-G, and the low-profile G815/G915 with GL switches, do not.

Are Razer and Corsair keycaps replaceable?

Usually yes on the stem, since both brands use MX-style stems on most models. But Corsair in particular has used non-standard bottom row sizes, so you may not be able to replace every key with a standard kit.

Do keycaps fit membrane or laptop keyboards?

No. There is no switch stem to mount onto.

Will a keycap set made for a 60% keyboard fit a full-size one?

The individual caps will fit — same stem, same sizing. But you won't have enough of them, and you'll be missing the function row, navigation cluster, and numpad. Buy a kit that lists your layout size under its coverage.

Are PBT keycaps compatible with every MX switch?

Yes on mounting. The only exception is that some thicker-stemmed switches (notably Kailh BOX) can slightly stretch softer ABS keycaps over time. PBT is more resistant, and it's one more reason to prefer it.

So — are keycaps universal?

Almost. If your keyboard runs MX-style cross switches and a standard bottom row, the entire aftermarket is open to you, and swapping caps is the single cheapest upgrade you can make to how a keyboard feels and sounds.

If it runs Topre, Alps, Romer-G, a dedicated low-profile switch, or buckling spring, you'll need a set made for that mount — and forcing a standard cap on will cost you a keycap.

Spend sixty seconds on the check above. It's the difference between a satisfying five-minute install and a disappointing package on your desk.