Travel music keyboard

Keyboards (pianos, synths, MIDI controllers, accordions) are very popular musical instruments; a plethora of them has been devised through the ages. Much to the dissatisfaction of an amateur performer, the equipment is often bulky and unsuitable for practising while travelling (think instead of the convenience of a flute or a recorder).

I decided to run a little analysis to check if such chimera exists: a keyboard which can be used to play a reasonable amount of musical literature, while also being travel-friendly.

Minimal range

To get a feeling of what range the music I play is, I consulted the excellent Open Hymnal Project (PDF): chorales are harmonically pleasing, have a number of different voices (usually four) and there are many of them. As a bonus, the OHP not only does provide its Hymnal as a PDF, but in ABC notation format too; this allows for simpler data processing.

The idea is quite simple, we take a chorale like this one:

four bars from a chorale

then we check the lowest and highest note (highlighted in red: B♭ and E♭). The distance in semitones between those two notes is the measure we are looking for (in this case: 30 semitones).

Here is a table with the range frequency:

Range # of chorales
25 2
27 2
28 3
29 7
30 32
31 1
32 93
33 29
34 65
35 34
36 6
37 20
39 6
41 3
42 2
48 1

Looking at the the cumulative graph of all the 306 chorales is more interesting (keep in mind that 1 octave = 12 semitones):

cumulated number of playable chorales over range (gnuplot)

It is clear how a two-and-a-half keyboard won’t cut it and how a four-octave one is a waste: most of the chorales (294/306 = 96%) are playable on a three-octave keyboard.

Optimal 3-octave layout

This is not the end of it. After all you would not be able to play this interval of a fourth (A4-D5) on an octave sized C-to-C keyboard:

an octave interval (B-B) and an octave-sized keyboard

This is because the starting note in the layout matters (and indeed picking C is particularly ill-conceived if portability is a plus).

Here I tabulated all the possible 3-octave keyboard layouts by starting note. Again, the comparison concerns on the number of playable chorales (out of 306).

Start note Playable chorales in %
C 21 7%
C♯/D♭ 33 11%
D 172 56%
D♯/E♭ 220 72%
E 266 87%
F 266 87%
F♯/G♭ 200 65%
G 178 58%
G♯/A♭ 72 24%
A 48 16%
A♯/B♭ 19 6%
B 4 1%

Starting on E and F is the best choice; replicating the analysis on other collections (Frescobaldi, Bach, Palestrina) showed a slight advantage of F-to-F over E-to-E. The playable-chorales percentage drops from 96%, but it is still high (87%).

This was common knowledge in the past: small keyboard instruments (like this clavichord) started on F to accommodate more music on less keys.

Carry-on friendliness

Now that we know what a good layout is, let us see what options are travel friendly. Carry-on specifications by the International Air Transport Association are “[a maximum] size of 55 x 35 x 20 cm”. After a bit of research, I found two choices that fit the requirement:

Transposition matters

Much to my dismay, most three-octave MIDI controllers come with the C-to-C layout; this strongly limits the playable repertoire on the instrument.

A solution is to shop for the (uncommon but existing) F-to-F layout, but if you are ready to invest in your musical education, learning how to transpose at sight is an option. You mentally shift each note up by a fourth (i.e. playing an F when you see a C written on the score) while instructing your controller or software to lower the output by a fourth (a feature present in every MIDI keyboard).

I am practising this skill and, despite requiring mental effort, it is not as difficult as it sounds. I plan to dedicate more time to it and then write an article on how to best approach the matter.


Playing interesting literature on a small, travel-friendly music keyboard is possible. Happy travelling light everyone!