The most popular keyboard layout QWERTY was invented back in the 1800s. There have been multiple layouts being introduced throughout the years, but for the simplicity of our discussion, we will be referring to QWERTY moving forward. It is essential to understand terminologies to establish mutual understanding and avoid confusion. To do just that, lets dive a bit into the terminologies and the anatomy of keyboard layout in the keyboard community,
Anatomy
For the purpose of discussion, let's break a keyboard layout down into three major clusters: the Alphas + Mods, the Navigation, and the Numpad clusters.
Alphas contain all the alphabetic, numeric, and punctuation characters, whereas Mods contain all the essential keys such as Esc, Backspace, Enter, Tab, Ctrl, Alt, Shift, etc….
The Navigation cluster contains Arrow keys, as well as secondary Navigation keys such as Insert, Delete, Home, End, Page Up, and Page Down.
Numpad, as the name implies, is the Number Pad containing numerical characters in a grid layout for ease of one-handed operation. This is heavily used for number-intensive tasks such as data entry or accounting. However, due to the specific designated use and the fact that Alphas already contain numerals, the Number Pad is often the first part of the layout subtracted for more compact layouts.
In the world of Mechanical Keyboard, we reference key sizes with the unit “u”. A typical square alphanumeric key is 1u, whereas longer Mod keys are represented by the multiples of that, such as 2u for Backspace and 2.25u for Enter.
There are also extra features such as an LED Display, Rotary Knob, and Badge. The LED Display and Rotary Knobs have shown a recent uptick in popularity as keyboard designers strive to make their keyboards stand out. An LED Display provides functional features such as displaying time and layers, whereas a Rotary Knob provides control such as controlling volume, executing adjustment functionalities in specific softwares, as well as an additional push button. A Badge is an aesthetic design feature that typically provides no additional functionality but can lend a bit of character/personalization to a board.
Full Size
The Full size layout has the most keys and is the largest layout with the most utility. However, the tradeoff is the comparatively larger footprint that houses superfluous keys that some might not use, not to mention the sheer size. For these reasons, this layout is not very popular in the custom mechanical keyboard community.
1800
The 1800 layout is a compacted version of a Full Size, with the Navigation cluster condensed down to just Arrow keys, and relocating some Navigation keys to the top of the Numpad. For ease of use, the Arrow cluster is still exploded, meaning there is some space between the Arrow cluster and the rest of the keys to provide easy identification and avoid mis-clicks. This “Exploded Arrow” approach is often seen in smaller layouts to achieve the same purpose.
96%
If you can’t live without a Numpad and Arrow keys, and want to minimize the footprint of your keyboard, 96% is for you. It is basically 1800 layout without exploded Arrows. All keys are packed together on a 96% board, leaving you with no gap, just a sea of keys for your fingers to swim in. Some people love the compactness with almost full utility, while others find the gap-less layout less user friendly. Here comes the magical phrase for this hobby - It’s all personal preference! Pick what works for you.
Tenkeyless (TKL)
Here we begin to tread into enthusiast territory. Tenkeyless (TKL) is a full size layout without the Numpad cluster. The 10-key is just a metaphor for the Numpad, referring to number 0 to 9. Since there is still the Number row on top of the Alphas, for those that don’t use Numpad regularly, TKL is a great layout that does not compromise on functionality, while reducing the footprint of the keyboard. For many, this is considered the best layout in terms of being a standard layout that does not require special keycaps kitting, retaining functionality with a small footprint, and featuring a timeless aesthetic in terms of layout.
75%
We continue our quest to reduce the footprint by trimming down more keys. When you reduce the Navigation keys from a cluster to a single column, and trim the bottom right corner of the Alphas and Mods so you can tuck the Arrow keys into it, you get 75%. This layout retains most of the Navigation keys from the TKL while providing an even smaller footprint.
65%
The 65% is basically a F-rowless 75%. The entire function row (F1 to F12) is eliminated to make the board shorter and more compact. If you are one of those who do not use Function keys often and wish to claim the space they occupy, this layout would be perfect for you. Keep in mind that when the Function row is removed, the ESC key has to be moved one row down to the tilde (~) key location (left of the “1” key). You might ask, what if I want to type “~”? Therefore, it is in this layout that we begin to see the use of layers.
Layer, in the mechanical keyboard world, refers to the use of a key modifier to execute a different key input that is not as labeled/ intended under normal use. A simple analogy would be Shift, where holding down Shift while typing the Number keys would input symbols that are normally not accessible otherwise. Layering takes this idea into hyperdrive, where you can define any keys to input anything you want when you activate a Layer. There are multiple ways to trigger a Layer,
Using it similar to Shift, where you hold down a key to activate the Layer.
Using it similar to Caps lock, where you tab a key to toggle the Layer on, and again to toggle it off.
Layering is the definitive tool that enables people to use compact layouts that are even smaller than 65%, because otherwise the loss of functionality would not warrant the gain in desk space.
60%
As we continue to pursue smaller form factors, we arrive at the most popular of all (at least among enthusiasts) -- 60%. 60% is the ultimate compact layout that provides the golden ratio of small size and usability. Simply defined, it is a full-size keyboard without the Numpad, Navigation Cluster, and Function row. A standard 60% looks exactly like the Alphas + Mods cluster cut out from a full-size keyboard.
The advantage of a standard 60% is immediately apparent. It features:
Full standard keycaps compatibility
Compactness
Universal nature due to the layout being a standardized size rectangle with no gaps or extra spacings. This layout leads to the production of cases and parts that can be used interchangeably, and makes the 60% layout even more popular.
However, the layout also have some glaring concerns for some,
Lack of dedicated Arrow keys
Lack of Function and Navigation keys
Keyboard enthusiasts try to overcome the shortcomings of this compact layout with the following,
Use of Layers: Arrow, Function, and Navigation keys can be accessed in a separate layer
Use of split keys: ever wonder why the Right Shift needs to be that long? Well, you can split it into a shorter Shift and a 1u key, and now you have an extra key without changing the layout! This is a very common option – using a Split Right Shift, to provide an additional key (usually as a layer modifier key) for whatever functionality you desire. Other common split keys include Split Backspace, where the Backspace is moved down to the Pipe/ Backslash key and the 2u Backspace is split into two 1u keys, typically the Pipe/ Backslash key and the tilde key.
Modified 60%: change the bottom right corner of the layout to accommodate additional keys, sometimes even dedicated Arrow keys. This however, take away the full standard keycaps compatibility advantage of a standard 60%, and some consider the modified 60% layout to be aesthetically inferior.
HHKB
HHKB stands for Happy Hacking Keyboard, which was developed with the philosophy to reduce a keyboard to a more compact yet functional layout that could be used with a variety of different computer systems. Since its release in 1996, the design has garnered quite a following, so much so that the name HHKB is commonly used not only to refer to the keyboard itself, but also to the unique layout. HHKB occupies the same physical footprint of 60% minus keys at the bottom right and left corners. It is a layout codeveloped by Japanese computer scientist Eiiti Wada and PFU Limited. The keyboard uses a Topre electrostatic capacitive key switch, which differs from the typical mechanical key switch. The HHKB layout has been implemented in custom mechanical keyboards to utilize typical mechanical keyboard switches. The compact layout utilizes a Split Right Shift to provide an extra function key, which is used to activate the extra layer.
50%
As we examine keyboards smaller than 60%, we see a significant drop in ease-of-use. The idea behind layouts smaller than 60% is to have more keys reachable within one key finger reach. To achieve this, the Number Row is taken out. Layer becomes essential in smaller layouts, and there is a learning curve that is otherwise not present in larger layouts. Unlike other more commonly used layouts, there is no one definitive standard 50% layout. Different designers have different takes on this smaller form factor. Some still provide all Punctuation keys with the Alphas, while some decide to take a few off.
40%
We have reached the pinnacle of compactness -- 40%. This is the most common compact layout in the community, and has the largest assortment of varieties within one specific layout category. Similar to 50%, there is no Number Row, and no Punctuation keys. Layers are needed to access almost every key outside of Alphas. Due to the steep learning curve, this is not a layout for everyone.
Numpad
Numpad is just the Numpad cluster from a Full Size keyboard as a stand-alone option. It is a modular piece of keyboard that can be used independently, and is handy for people who use the Numpad often. The advantage of having a separate Numpad is the ability to put it away when not needed. Most custom Numpads incorporate extra functionality such as an extra row, buttons, knob, or even OLED screen.
Macropad
Sometimes you just want to have a few keys that are custom programmed to execute certain commands or operations -- this is where a Macropad comes into play. Although, most of the time, keys on a custom Mechanical Keyboard can be programmed to do almost anything, it is good to have dedicated keys, especially if those keys are used often. A Macropad comes in a variety of shapes and sizes from different designers, and a lot of people actually use it as an artisan display deck.