Keyboard Sizes and Layouts
What the percentages actually mean, why layers replace the keys you lose, and the bottom-row differences that decide whether keycaps will fit.
Keyboards are sold by percentage: full-size, 75 percent, 65, 60, 40. The numbers are useful shorthand and slightly misleading, because they do not describe a percentage of anything in particular.
This page is about how layouts work: what the names mean, what happens to the keys that are missing, and the small differences that decide whether a set of keycaps will fit your board. If you want a size-by-size walkthrough with the trade-offs of each, read choosing a keyboard size.
What the percentages mean
Roughly, the width relative to a full-size keyboard, and only roughly.
A full-size board is 104 keys in the standard US layout. A tenkeyless is the same thing with the number pad removed, which is about 80 percent of the width, and everybody calls it TKL rather than 80 percent. A 60 percent board has 61 keys, which is 59 percent of 104, so the name is close. A 40 percent board has around 47 keys, which is 45 percent, so the name is not.
Treat the number as a rough width, not a count, and remember that two boards with the same percentage can have different key counts.
The four regions
Every layout is the full-size layout with regions removed, in a consistent order. Knowing the order is more useful than memorising the names, because it tells you what any given size has.
- Alphas. The letters, numbers and punctuation, plus the modifiers around them. Never removed.
- Number pad. The calculator block on the right. First to go.
- Function row. F1 to F12 along the top. Second to go.
- Navigation cluster. Arrows, plus Home, End, Page Up, Page Down, Insert, Delete. Removed last and in pieces, since the arrows usually survive after the rest of the cluster has gone.
So: full-size has all four. TKL drops the number pad. 75 percent keeps the function row and arrows but squeezes them together, losing the gaps. 65 percent drops the function row and keeps the arrows. 60 percent drops the arrows too. 40 percent drops the number row as well, which is the point at which the board stops resembling a keyboard.
Two sizes do not fit the pattern:
- 1800 or 96 percent: a full-size board with everything pushed together so the number pad touches the arrows. All the keys, much less width.
- 75 percent exists in two forms, one a compressed TKL with a column of navigation keys down the right, the other a 65 percent with a function row added.
Layers, which are what you actually lose
Removing a key does not remove the function. A 60 percent board still has F5 and Page Down; they just need a modifier.
Custom boards nearly all run QMK or VIA firmware, which means every key can be reassigned and the board can have several layers. Hold a designated key, usually labelled Fn, and the whole board becomes a second set of assignments: the number row becomes the function row, and a cluster near your right hand becomes the arrows.
This is the part that decides whether a small board works for you, and it is not really about the keyboard. It is about whether you will build the muscle memory. Two honest observations:
- Arrows on a layer under your right hand, reached without moving your hand, are genuinely better than reaching for a dedicated cluster. Most people who make the switch do not want to go back.
- Anything you use rarely and suddenly, a function key in a specific application, a Print Screen, is worse on a layer, because you will not remember where you put it.
The keys you should think hardest about are the ones you use constantly without noticing: arrows, Delete, and on a small board, the number row.
The bottom row, which decides your keycaps
Here is the practical detail that catches people, and it has nothing to do with size.
Boards of identical size can have different bottom rows, and keycap sets are cut for specific bottom rows. The variations have names:
- ANSI standard: 1.25u modifiers either side of a 6.25u spacebar. What almost every prebuilt uses.
- Tsangan: 1.5u modifiers and a 7u spacebar, a layout inherited from older boards and very common in custom kits.
- WKL, winkeyless: Tsangan with the Windows keys removed, leaving a blank 1.5u space either side of the spacebar.
- HHKB: a 60 percent variant with a shorter right shift and the extra key moved next to it, plus a 6u spacebar.
The spacebar is the part that matters most, because a 6.25u set cannot fill a 7u board and there is no workaround. Check your board’s spacebar width before buying keycaps, which is covered in more detail in keycaps and keycap sizes.
ISO versus ANSI is a separate axis that applies at every size. ISO boards, standard across much of Europe, use a tall L-shaped enter, a shorter left shift and an extra key beside it. ANSI keycap sets do not include those keys unless they offer an international kit.
Layouts that are not rectangles
Everything above assumes keys in offset rows, staggered the way typewriters were. Three families reject that.
Ortholinear. Keys in a perfect grid, no stagger. The argument is that the traditional stagger exists for typebar linkages in mechanical typewriters and has no ergonomic purpose. Learning it takes a couple of weeks and breaks your touch typing in the meantime. Boards are usually 40 to 50 percent sized, because a grid gets wide quickly.
Split. Two separate halves joined by a cable, so each hand sits where it naturally falls and at whatever angle suits it. This is the only layout change with a clear ergonomic case behind it rather than an aesthetic one. Most splits are also ortholinear or column-staggered, so you are usually learning two things at once.
Alice and ergo. A single board with the two halves angled inward, so your wrists stay straighter without separating the halves. Much easier to adopt than a split, since the stagger is still the familiar one, and it keeps the board as one object.
All three share a problem worth knowing before you buy: keycaps. Non-standard layouts need key sizes standard sets do not include, so you need a set that sells an ergo or 40s kit, and many do not. On an ortholinear or split board a uniform profile such as DSA or XDA is the usual answer, since any cap fits any position.
Where to go next
If you are choosing a board, choosing a keyboard size goes through each size with what you give up. If you want to identify a layout you are looking at, the layout sheet has the outlines.