Concertina Fingering

What does this tool do?

This tool finds the optimal fingering route for any tune on a 30-button Anglo concertina in C/G. You paste in a tune in ABC notation, and the tool tells you which button to press for each note — and whether to push or pull the bellows.

Because many notes can be played on more than one button, there are often hundreds or thousands of possible combinations for a whole tune. This tool searches through all of them and picks the route that is easiest to play — minimising awkward jumps, finger hops, and unnecessary bellows reversals.

The Anglo concertina

An Anglo concertina is a bisonoric instrument: each button produces a different note depending on whether you push or pull the bellows. A standard 30-button C/G Anglo has two sides (left hand and right hand), each with three rows of five buttons.

Left hand

Right hand

Rows are named t, c, and g (the main push notes of each row on the left side). Buttons are numbered 1–5, with 1 closest to the player. This tool covers all 60 button positions (30 push + 30 pull).

Button map (C/G Anglo, this instrument)

The note layout below matches exactly what is stored in KEYS_DATA. If your concertina differs, the source code can be adapted. Blue = push Red = pull.

	← Left hand (outer to inner)					Right hand (inner to outer) →
Row	btn 5	btn 4	btn 3	btn 2	btn 1	btn 1	btn 2	btn 3	btn 4	btn 5	Row
t	E1F1	A1B♭1	C#2D#2	A2G2	G#2B♭2	C#3C#3	C#3D#3	G#3G3	C#4B♭3	A4D4	t
c	C1G1	G1B1	C2D2	E2F2	G2A2	C3B2	E3D3	G3F3	C4A3	E4B3	c
g	B1A1	D2F#2	G2A2	B2C3	D3E3	G3F#3	B3A3	D4C4	G4E4	D#4F#4	g

How to use the tool

1. Paste your ABC notation

Copy a tune in ABC format and paste it into the text area on the left. You can find thousands of tunes in ABC format at sites like thesession.org or abcnotation.com.

A minimal example:

X:1
T:The Kesh Jig
R:jig
M:6/8
L:1/8
K:Gmaj
|:GAG GAB|ABA ABd|egd edB|dBA ABd:|

2. Click Analyse

The tool parses the tune, reads the key signature, and runs the search. For most tunes this takes well under a second. The Tune Info panel on the right shows the metadata extracted from the ABC headers.

3. Read the results

Two panels appear:

Best Fingering — a table with one row per note, showing which hand, row, direction (push/pull), and button number to use.
Button Diagram — a visual overview of all 60 buttons for each note in the tune.

Reading the button diagram

Each small diagram represents one note in the tune, labelled by position and note name (e.g. 3. G3). Inside each diagram, all 60 buttons are shown as dots:

Large blue dot — the recommended button, pressed on the push stroke.

Large red dot — the recommended button, pressed on the pull stroke.

Smaller blue/red dot — an alternative button that also appears in the best routes. Larger = used more often.

Small grey dot — button not used for this note in any of the best routes.

Example — three consecutive notes from a jig in G (G3, A3, B3):

Left-hand buttons appear on the left side of each diagram, right-hand buttons on the right. Within each side, button 1 is closest to the centre and button 5 is outermost. The three rows (t, c, g) run top to bottom.

ABC notation basics

ABC is a text-based music notation format. Here are the header fields this tool uses:

Field	Meaning	Example
`X:`	Tune index number	`X:1`
`T:`	Title	`T:The Kesh Jig`
`R:`	Rhythm / tune type	`R:jig`
`M:`	Time signature	`M:6/8`
`L:`	Default note length	`L:1/8`
`K:`	Key signature	`K:Gmaj`

Note notation

ABC	Note	Octave
`C, D, E,` …	C, D, E …	Octave 1 (very low)
`C D E` …	C, D, E …	Octave 2
`c d e` …	C, D, E …	Octave 3 (middle)
`c' d' e'` …	C, D, E …	Octave 4 (high)

Sharps in the key signature are applied automatically from the K: field. Explicit accidentals (^ sharp, _ flat) in the note line are not yet supported — these are stripped during parsing.

Supported keys

The tool automatically applies the correct sharps for the following keys:

Note sharpened	Keys where it applies
F → F#	G, D, A, Em, Bm, Cm, Edor, Ador
C → C#	D, A, E, Bm, Edor
G → G#	E, A

Keys not in this list are treated as having no sharps (e.g. C major, A minor, D Dorian).

How the algorithm works

The search is a beam search. For each note in the tune, all possible buttons that produce that note are looked up. The algorithm then builds all combinations, step by step, keeping only the most promising routes at each step.

Each transition between two buttons gets a score based on:

Same hand as the previous note → small bonus
Same button, different direction (push→pull or pull→push) → bonus (this is natural bellows reversal)
Same finger jumping to another button → heavy penalty
Preferred rows (c and g) → bonus
Preferred button numbers (1 and 2) → small bonus
Outer buttons (5) → small penalty

When the number of routes exceeds 4,096, the worst-scoring routes are pruned. The route with the lowest total score is returned as the best fingering.

Limitations

The tool is tuned for a standard 30-button C/G Anglo concertina only.
Notes outside the instrument's range (roughly E1–F#4) are silently skipped.
Explicit accidentals (^c, _B) in the note line are not yet parsed.
Chords (multiple simultaneous notes) in ABC notation are not supported.
The algorithm finds an optimal route, but "optimal" is based on a scoring model — experienced players may prefer different choices in some passages.

Tip: If you get unexpected results, check that the K: key field is present and correctly spelled in your ABC. The key signature has a big effect on which notes get sharpened.

About

This tool was originally written in Ruby in 2015–2018 under the name MUPHIN. The JavaScript port and web interface were created in 2024. The source code is available publicly — feel free to study, adapt, or improve it.

If this tool has been useful to you, consider buying the author a coffee: paypal.me/muphin