Colemak Mod-DH

A Colemak mod for more comfortable typing.

(rev 2)

Colemak Mod-DH

Mod-DH is a minor modification to the Colemak keyboard layout, designed to make typing more comfortable.


Colemak Mod-DH main keys, shown for an ISO keyboard. Keys are colored according to the finger that should be used. The 10 most common English letters are assigned to the 10 easiest keys (highlighted in red).

Colemak is a great layout, but that doesn't mean it's impossible to improve on! The idea behind Mod-DH is that by making an adjustment to the placement of a small number of keys, it is possible to gain a significant improvement in ergonomics and comfort. See this comparison of Mod-DH with other layouts.

There are separate implementations optimized for ISO, ANSI and matrix keyboards.

Highlights:

The Colemak forum has threads containing some background information to the creation of this mod, and also a more detailed discussion of it.

Changes From Colemak

The mod consists of two parts, the left-hand "D" change, and the right-hand "H" change.


Changed keys relative to standard Colemak. Note that none of the changes move keys to a new finger. This makes the mod easy to learn and also retains Colemak's excellent stats on same-finger bigrams.

Left Hand Changes

The primary change is to the left hand:
1. The "Angle Mod" (see below) is applied to keys Z, X, C. This moves them one space to the left but retaining the conventional finger.
2. Three keys are relocated: D, G, B. This makes the D key much easier to type, using your index finger. The position of G is also improves, and reverts to its Qwerty placement. The B key moves from the hard-to-reach position at the bottom-middle to the new location on the top row.

Right Hand Changes

There is a minor change to the right hand:
The H, M and K keys move. This makes H (the most frequent character of the three) easier to type. Since HE is the second most common bigram in English, it also makes it much more comfortable to type very common words such as "the", "then", "where", etc. The M key moves one space to the left, taking the next-best available spot.

Changes From Qwerty


Changed keys relative to Qwerty. In total, 19 keys are changed, plus the application of the Angle Mod to an additional 3. Of these, only 12 keys change fingers, same as Colemak.

If you are currently using Qwerty and looking for a better layout, then both standard Colemak and Mod-DH are excellent choices. The change from Qwerty is not easy and can take some time, but is worthwhile in the end. If you start with Colemak but find the frequent reaching for D, H and G unsatisfactory, or find the common HE bigram uncomfortable, then Mod-DH is for you!

What's wrong with standard Colemak anyway?

For many people, nothing! But others who have tried Colemak have identified flaws, and have found the transition from Qwerty frustrating as a result. Some have even given up on Colemak and looked to other layouts instead. I believe that those who experience problems with Colemak need not give up on it. Mod-DH was created to fix the most common complaints, and to give a more comfortable Colemak experience for those who want it.

The most commonly identified flaw is Colemak's placement of the D and H keys. As the 8th and 10th most common letters in English, they should ideally be in easy-to-reach positions. Colemak places them on the centre column, which means a lateral motion of the hand is required to access them. If you try this motion frequently, you'll probably find it is somewhat less comfortable than simply moving the index finger down, to where Mod-DH places those keys. The H-E combination is often cited as a common English bigram that is unduly awkward with Colemak. If you think it's easier for the index finger to reach down one key to the bottom row than to the centre column, then you'll find Mod-DH more comfortable to use.

left right total
Colemak 7.76% 7.02% 14.78%
Mod-DH 4.49% 3.31% 7.80%
Usage of the centre-column keys for standard Colemak and Mod-DH

My own experience is that I used standard Colemak for several months, but was somewhat unsatisfied with the frequent reaching for the middle of the keyboard to type D and H, and to some extent G. But I stuck with it, being reluctant to change an established layout and thinking Colemak's other benefits would outweigh its drawbacks. And to be fair, for the most part they do. But I eventually came to realize that in fact there is no need to compromise: By applying Mod-DH, it is possible to retain Colemak's best features, while placing some common letters in easier to access locations and reducing the need to reach for the centre column. Within a couple of days using the left-hand "D" mod, I found it to be a noticeable, significant improvement over standard Colemak. And when applying the right-hand "H" mod, common English words containing HE (the, then, where…) become almost effortless.

The Colemak D and H keys (indicated by crosses) are moved to the more comfortable positions for the index finger, on the bottom row (indicated with ticks).

The Angle Mod

The "Angle Mod" makes it possible to adopt a more comfortable typing posture by introducing a degree of symmetry on a standard, staggered keyboard. The keys along the bottom-left are moved one space to the left, but you should type these keys with the conventional finger, Z=pinky, X=ring, C=middle, V=index. This mod is used by many existing Colemak users.

For more information, see this Guide to the Angle Mod.

The Angle Mod is a good innovation, but in its default application it assigns the rare V to one of best locations on the keyboard. Mod-DH fixes this by assigning D to that key instead. An important feature of Mod-DH is that on standard keyboards, use of the Angle Mod idea is intrinsic to the layout design.

Revisions

The original Mod-DH was launched in October 2014. Following feedback from users, a minor revision was been made in May 2017, switching the original M and K key positions. Users of Matrix boards may prefer to retain M on the home row.

Implementations for Keyboards

There are implementations available for ISO, ANSI, and matrix (orthogonal) keyboards, for a variety of operating systems. See the Keyboard Types page for example implementations.

Feedback / Issues

License

The keyboard layout and the implementations are available under the public domain. You have the right to freely use it for any purpose, without any conditions. Attribution is strongly encouraged, but not required.

The downloadable software is provided "as is", without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. In no event shall the authors or copyright holders be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or the use or other dealings in the software.