You found a keycap set you like. Before you click buy, one layout question decides whether every key actually seats: ANSI or ISO?
The two layouts look similar from a photo. On the desk they are not interchangeable. The Enter key is a different shape. ISO boards add a key to the left of Left Shift. If the kit does not include those pieces, you will have a gap — or a leftover key that does not belong.
This guide shows how to identify your board in under a minute, what to check on a product page, and how kit size (104, 108, 115) maps to real coverage.
What ANSI and ISO actually are
ANSI and ISO are physical keyboard layouts, not keycap materials and not switch brands.
ANSI is the common US / most-of-North-America layout:
- Wide, horizontal Enter key (one row tall, about 2.25u)
- Left Shift is a long 2.25u key
- No extra key between Left Shift and Z
- Typical full-size count: 104 keys (or 87 on tenkeyless)
ISO is the common UK / much-of-Europe layout:
- Tall L-shaped Enter (two rows)
- Left Shift is shorter, because an extra 1u key sits to its right (ISO extra / “ISO hash” key)
- Typical full-size count: 105 keys (or 88 on tenkeyless)
Japan’s JIS layout is a third family (extra keys near Space and a different Enter). If your board is JIS, do not assume an ANSI or ISO kit will fill it.
Material (PBT vs ABS) and profile (Cherry vs OEM) do not change this. A Cherry-profile PBT set still needs the right shapes for your layout. For material basics, read PBT vs ABS. For a full beginner map of profiles and compatibility, start at Custom Keycaps 101.
60-second physical check
You do not need a spec sheet. Look at two keys.
- Enter. One wide bar = ANSI. Tall backwards-L = ISO.
- Left Shift. If there is a small extra key between Left Shift and Z, you are on ISO (or a similar non-ANSI layout).
Also count the keys in the bottom row. ISO often keeps the same Spacebar family as ANSI, but the left cluster is where kits fail first.
If you bought the keyboard in the UK, DE, FR, or Nordic regions, ISO is the default until the check says otherwise. US retail boards are usually ANSI.
Why kits fail on ISO (and sometimes on ANSI)
Keycap sets are sold as “kits,” not as a promise that every layout on Earth is included.
Typical gaps:
| Missing piece | Who feels it | What you see |
|---|---|---|
| ISO Enter (large inverted-L) | ISO boards | ANSI Enter sits in a hole that is the wrong shape |
| Extra 1u left of Left Shift | ISO boards | Short Shift with a naked switch |
| Extra 1u right of Left Shift on some 75% / 65% | compact boards | Split Shift / extra blocker keys |
| Split Backspace / split Left Shift | 60% and 65% | Standard 104 kit leaves two switches uncovered |
| Numpad | TKL owners buying a 104 kit | You simply will not use those keys — that is fine |
A 104-key “full ANSI” kit is enough for a US 104 or 87 board. It is not enough for ISO unless the listing explicitly shows ISO Enter plus the extra 1u.
Larger kits (108 / 115 / 135) exist to add those extras, plus extra modifiers some compact boards use. Bigger number ≠ automatic ISO. Always open the kit diagram.
How to read a product page before you buy
On any set — including a dye-sub PBT kit or a 115-key PC set — check these in order:
- Key count in the title or specs (104 / 108 / 115 / 135).
- Kit photo or legend map. Look for the tall ISO Enter and the small key next to Left Shift.
- Layout list. “ANSI / ISO” written out is useful; a diagram is better.
- Profile. Cherry-profile sets will not sit flush on an SA board even if the layout matches.
- Stem. MX-style cross stem is the usual case; do not mix in optical / ToPre / some laptop scissor boards.
If the page only shows a US 104 silhouette and your Enter is tall, skip it or message the shop with a photo of your board before ordering.
A 115-key kit has more spare shapes than a 104-key kit, which improves the odds of covering ISO extras and a few compact-board modifiers. It still does not replace checking the map.
Which layout to buy for office vs travel boards
Office / full-size / TKL (US): ANSI kit. Match profile to the board you already like.
Office in UK/EU: ISO kit, or a larger kit whose diagram includes ISO Enter.
75% / 65% / 60%: layout first, then kit size. These boards often need extra 1u modifiers that neither a cheap 104 ANSI kit nor a generic ISO add-on includes. Use the product diagram against a photo of your board.
RGB shine-through: layout still comes first. A see-through legend on the wrong Enter shape does not help.
Side-by-side: ANSI vs ISO vs “just buy a bigger kit”
| Check | ANSI | ISO | Larger kit (e.g. 115) |
|---|---|---|---|
| Enter shape | Wide 1-row | Tall 2-row | May include both — confirm diagram |
| Extra key by Left Shift | No | Yes | Often yes — confirm diagram |
| Typical full-size count | 104 | 105 | 115+ mixed extras |
| Fits a US TKL | Yes (ignore numpad keys) | No, Enter will not seat | Only if ANSI Enter is in the bag |
| Fits a UK full-size | No | Yes | Only if ISO pieces are in the bag |
| Compact 65%/75% | Maybe | Maybe | Better odds, still check extras |
FAQ
Can I put ANSI keycaps on an ISO keyboard?
Only if the kit includes the ISO Enter and the extra 1u by Left Shift. Dropping a wide ANSI Enter onto an ISO board leaves a gap and an unused switch.
My Enter looks like an upside-down L. What do I need?
That is ISO Enter. Filter for kits that show that shape in the kit photo, not only a US 104 render.
Does Cherry profile change ANSI vs ISO?
No. Profile is height and sculpt. Layout is which units and which shapes you receive. You can have Cherry-profile ANSI and Cherry-profile ISO.
I have a 75% board. Is 104 enough?
Often no. Many 75% boards use extra 1u keys around Enter, Shift, or the function column. Compare the kit map to your board photo key-by-key.
Where should I start if I am new to kits?
Read Custom Keycaps 101 for materials, profiles, and stems, then come back to this page for layout. When you are ready to pick a set, open a product page and match the kit diagram to your Enter key.
If your Enter is a wide bar, shop ANSI-friendly kits. If it is a tall L, do not buy until the listing shows that L in the bag. Layout first, then colorway.
— The KeycapsHub Team