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⚡ Quick answer
Most keycap sets fit most MX-style keyboards, but two things decide whether a whole set fits: the switch stem (it must be MX-style) and the bottom row (every modifier and the spacebar must come in your board’s sizes). Compact boards add a third: the 1.75u right Shift and 1u right-hand keys most 75% and 65% layouts use. Run the 10-point checklist below against your exact model before you buy.
“Fits most mechanical keyboards” is on nearly every keycap listing, and it’s usually true for the letters. It’s the edges of the board, the bottom row, the right Shift and the odd keys around the arrows, that catch people out. This page gives you a printable checklist to run against your own keyboard, and worked examples showing how the checks play out on real boards. For the spacebar specifically, our spacebar sizes guide shows how to measure one.
First: what “u” means
Key sizes are measured in units (u). One unit is the width of a standard letter key, based on a 19.05 mm key spacing. A Tab key is usually 1.5u, Caps Lock 1.75u, Backspace 2u and a standard spacebar 6.25u. When a listing says a set “includes 1.75u right Shift”, it means a Shift key 1.75 times the width of a letter key.
The 10-point keycap compatibility checklist
Work through it with your keyboard in front of you. Use the Print checklist button to print just this part, or save it as a PDF from the print dialog.
Keycap compatibility checklist
Keyboard model and revision: ______________________ Keycap set: ______________________
- 1. Switch stem: Is it a cross-shaped (MX-style) stem? Most keycap sets only fit MX stems. Topre, Alps, Kailh Choc and other low-profile switches need their own keycaps.
- 2. Switch orientation: Do the switches face north (LED at the top) or south? Some Cherry-profile sets can catch on north-facing switches; check the set’s notes if your board is north-facing.
- 3. Layout standard: ANSI, ISO or JIS? Look at the Enter key and left Shift. An ANSI-only set won’t give you an ISO Enter or a short left Shift.
- 4. Board size: Which keys does your board actually have: F-row, navigation cluster, arrows, numpad? Count them and match against the kit list.
- 5. Bottom row: Write down every bottom-row key size, left to right, and the spacebar length. This is where most sets fail to fit.
- 6. Shift row: Left Shift (2.25u ANSI, 1.25u ISO) and right Shift (2.75u full-size and TKL, 1.75u on most 75% and 65% boards).
- 7. Odd keys: 1u right-hand modifiers, an Fn key, macro keys, a split spacebar, a stepped Caps Lock or a 1.5u Backspace. Make sure the kit includes each one.
- 8. Profile rows: If the set is sculpted (Cherry, OEM, OSA, MT3), check the odd keys come in the row your board needs them on. Uniform profiles (DSA, XDA) avoid this.
- 9. Stabilizers: Does your board use Cherry-style or Costar (wire-clip) stabilizers? Keycaps for Costar boards need clips or inserts on the long keys.
- 10. Clearance: Very tall profiles (SA) can rub against a case lip or a knob on some boards. Check photos of the set on the same board if you can.
Bottom row, left to right (sizes in u): ___ ___ ___ ______ ___ ___ ___ ___ Right Shift: ____u
From clickyboard.com/keycap-compatibility-checklist/
Where to find your keyboard’s exact sizes
- The maker’s keycap size chart. Some makers publish one per model (Keychron does, for example, on a “keycap size” page for each board). Make sure it matches your exact model and revision, since sizes can change between versions.
- The keycap set’s kit list. Good sets show every key with its size and row. If a listing only shows a render of a full-size board, ask the seller or look for a kit image.
- Measure it. Pull a key and measure its width at the base. A 1u keycap is about 18 mm wide, so a 1.25u key is about 23 mm and a 1.5u key about 28 mm. For the spacebar, measure the distance between the outer stabilizer stems, as explained in our spacebar sizes guide.
Worked examples
Here’s how the checklist plays out on four boards. The first two use standard sizes and fit most sets that cover compact layouts. The last two are well-known cases of non-standard bottom rows. Sizes are taken from the maker’s published charts or support forums where available; we flag anything you should still confirm on your own board.
| Keyboard (version) | Layout | Bottom row, left to right | Right Shift | What to check |
|---|---|---|---|---|
| Keychron Q1 Max (ANSI, knob) | 75% ANSI | 1.25u × 3, 6.25u spacebar, 1u × 3, then 1u arrows | 1.75u | Kit must include the 1.75u right Shift, three 1u right modifiers and the 1u keys in the right-hand column. MX stems, south-facing switches |
| Keychron K2 (Version 2) | 75% ANSI | 1.25u × 3, 6.25u spacebar, 1u × 3, then 1u arrows | 1.75u | Same sizes as the Q1 Max, but the switches face north: some Cherry-profile sets are reported to catch on them, so check the set’s notes |
| Razer BlackWidow (older series; current V4 models differ) | Full-size ANSI | 1.5u Ctrl, 1u Win, 1.5u Alt, 6u spacebar, 1.5u Alt, 1u Fn, 1u Menu, 1.5u Ctrl | 2.75u | Most sets include a 6.25u spacebar and 1.25u modifiers, which won’t fit. You need a set with a 6u spacebar and 1.5u modifiers, or replace only the letters and numbers |
| Corsair K70 RGB (older K70 models) | Full-size ANSI | Non-standard: 6.5u spacebar (about 123 mm); measure each modifier | 2.75u | Very few sets include a 6.5u spacebar. Keep the stock bottom row or buy a set that lists your exact model. Newer K70 models may use standard sizes, so check yours |
Profile rows in practice: on a sculpted set, the 1.75u right Shift on a 75% board sits on the Shift row, and the right-hand column keys sit on several rows. Better sets include those keys in more than one row, so check the kit image shows the 1u keys you need in the rows you need them. With a uniform profile such as DSA or XDA, every key is the same shape, so any 1u key works anywhere. Our keycap profiles guide explains sculpted and uniform profiles.
The parts of the kit people forget
- ISO keys. The tall ISO Enter, the short 1.25u left Shift and the extra key beside it. Many sets sell these as an add-on kit. Our keyboard layouts guide shows how to tell ANSI from ISO.
- Novelties and 1u spares. Knob boards, macro keys and Fn keys use 1u caps; a set with extra 1u novelties covers them.
- Numpad. Full-size and 96% boards need numpad keys, including a 2u 0 and a 2u + and Enter (or 1u keys on some 96% boards).
- Split or short spacebars. Some compact and ergonomic boards use 2.25u + 2.75u split spacebars or a 7u bar on WKL (winkeyless) layouts.
Frequently asked questions
Are keycaps universal?
No. Most keycap sets fit most MX-style switches, but whether a full set fits depends on your layout and key sizes, especially the bottom row, the right Shift and any odd keys. Switches such as Topre, Alps and low-profile Kailh Choc need their own keycaps.
How do I know what size keycaps my keyboard needs?
Check the maker’s keycap size chart for your exact model, or measure your keys. A 1u keycap is about 18 mm wide at the base, a 1.25u key about 23 mm and a 1.5u key about 28 mm. Write down the bottom row and right Shift sizes before you shop.
Will a keycap set fit a 75% or 65% keyboard?
Only if it includes a 1.75u right Shift and enough 1u keys for the right-hand column and bottom-right modifiers. Many full-size sets do not, so look for a set that lists compact-layout support in its kit.
Why don’t keycap sets fit Corsair or Razer keyboards?
Some older Corsair and Razer boards use non-standard bottom rows, such as a 6.5u or 6u spacebar and 1.5u modifiers. Most keycap sets include a 6.25u spacebar and 1.25u modifiers, so the bottom row will not fit. The letters and numbers usually fit fine.
Do keycap profiles affect compatibility?
Profiles do not change whether a keycap fits the switch, but sculpted profiles mould each row differently, so an odd key from the wrong row will sit at the wrong angle. Uniform profiles avoid this. Very tall profiles can also rub against some cases.
Can I use MX keycaps on low-profile switches?
No. Low-profile switches such as Kailh Choc use a different stem and need matching low-profile keycaps. Some low-profile MX-style switches accept MX keycaps, but check the switch maker’s guidance.
Layout details checked on 7 October 2026 against maker pages and support forums. Keyboards change between revisions, so always confirm your exact model.