By the numbers
Guitar vs piano: which keys do scores really use?
Short answer
Of 364 guitar-solo scores in the Mutopia Project, 59.1% have a key signature with sharps and only 11.0% have flats. For 484 piano-solo scores it is the other way round: 43.0% flats against 34.7% sharps. C major is the commonest key for both (24.7% of guitar scores, 15.1% of piano scores), but the guitar then goes G, D, A and E major while the piano goes G major, F major, A minor and B♭ major.
- 59%of guitar scores have a sharp key signature (215 of 364)
- 43%of piano scores have a flat key signature (208 of 484)
- 4 of 5of the commonest guitar keys are named after an open string
Dataset: the Mutopia Project, 2,129 scores of which 364 guitar-solo and 484 piano-solo scores have a readable key. Solo means the score lists one instrument family. The key is the first key signature of the MIDI file made from the score. This is a collection of free-to-use scores (mostly Baroque to Romantic), not a sample of all guitar or piano music.
Sharps or flats?
Guitar and piano are on opposite sides. Among the other families, the harpsichord and clavichord scores are even more sharp-heavy than the guitar (86% sharps, from 35 scores), string ensembles lean to flats (26 of 37 scores), and the koto and shamisen scores almost never carry a signature (89% have none).
Which keys?
The guitar's top five (C major, G major, D major, A major, E major) are all keys with up to four sharps; the piano's (C major, G major, F major, A minor, B♭ major) include two flat keys and a minor key. Open-string keys explain part of the guitar's pattern: four of its five commonest keys (G, D, A and E major) are named after one of the six open strings (E A D G B E), which Wikipedia's tuning article gives, excerpted below. The data cannot say why; it only shows that the pattern is there.
| Rank | Guitar scores | Piano scores |
|---|---|---|
| 1 | C major — 90 (24.7%) | C major — 73 (15.1%) |
| 2 | G major — 62 (17.0%) | G major — 54 (11.2%) |
| 3 | D major — 58 (15.9%) | F major — 47 (9.7%) |
| 4 | A major — 55 (15.1%) | A minor — 35 (7.2%) |
| 5 | E major — 23 (6.3%) | B♭ major — 34 (7.0%) |
| 6 | A minor — 19 (5.2%) | D major — 27 (5.6%) |
| 7 | F major — 15 (4.1%) | A major — 22 (4.5%) |
| 8 | E minor — 14 (3.8%) | G minor — 21 (4.3%) |
How many sharps or flats?
Piano scores carry 1.9 sharps or flats on average, guitar scores 1.4, voice 1.3 and organ 1.1. The koto and shamisen scores average 0.11.
Time signatures differ too
Guitar scores most often use 2/4 (32%), piano scores 3/4 (29%); organ and voice scores are mostly in 4/4.
| Instrument | Scores with a time signature | Commonest signatures (share of that instrument's scores) |
|---|---|---|
| Piano | 502 | 3/4 29% · 4/4 28% · 2/4 19% · 6/8 11% |
| Guitar | 385 | 2/4 32% · 4/4 24% · 6/8 16% · 3/4 16% |
| Voice or choir | 258 | 4/4 56% · 3/4 16% · 2/2 7% · 6/8 7% |
| Organ | 173 | 4/4 62% · 3/4 8% · 4/2 8% · 3/2 7% |
| Violin | 50 | 4/4 30% · 3/4 24% · 2/2 10% · 2/4 10% |
Open strings and written pitch
Standard tuning and the way guitar music is written, from Wikipedia. The octave shift in guitar notation does not change the key, so it does not affect the counts on this page.
From Wikipedia
Guitar tunings: standard tuning
Standard
Standard tuning is the tuning most frequently used on a six-string guitar and musicians assume this tuning by default if a specific alternate (or scordatura) is not mentioned. In scientific pitch notation, the guitar's standard tuning consists of the following notes: E2–A2–D3–G3–B3–E4.
The guitar is a transposing instrument; that is, music for guitars is notated one octave higher than the true pitch. This is to reduce the need for ledger lines in music written for the instrument, and thus simplify the reading of notes when playing the guitar.
Source: Wikipedia, “Guitar tunings” — CC BY-SA 4.0 — text excerpted; see the article for the full text and authors. Revision of 2026-06-14.
How this was counted
- Dataset. The Mutopia Project, local clone: 2,129 scores (a score is counted once by its Mutopia id). The instrument comes from the header field mutopiainstrument, mapped to an instrument family; only scores with a single family count as “solo”.
- Key. The first key-signature event of the MIDI file made from the LilyPond source or, when there is no MIDI file, the first
\keyin the source. Where a score has both they agree in 95.9% of cases (1,669 scores). Modal keys are not named. - Sharps and flats. Counted from the signature itself: a signature with any sharps is a sharp signature; C major and A minor (no sharps or flats) are counted as none.
- Check. For every instrument family, flats + sharps + none add up to the number of scores with a key, and the listed keys never exceed it.
Data used
- The Mutopia Project — 2,129 free-to-use scores (LilyPond sources and the MIDI files made from them) for piano, guitar, voice, organ, violin and more; keys, time signatures and tempo marks are read from the MIDI or the source header. per piece: public domain, CC BY or CC BY-SA (only counts are shown here)
What these numbers cannot tell you
- The Mutopia Project holds the scores volunteers chose to typeset, so its guitar and piano scores are not samples of all guitar or piano music (there is no tablature, and these figures do not separate classical from folk or rock arrangements).
- The key signature shows the written key. Some scores change key later; only the first signature is used. Guitar scores are notated an octave above sounding pitch, which does not change the key.
- The data show that the pattern exists; they do not show why. The open-string explanation is a pattern in the names of the keys, not a tested cause.
- Instrument families with fewer than 20 scores (cello 15, lute and theorbo 7) are left out; the family labels come from Mutopia's own header field.
Checks run each time this page is rebuilt (51)
- all: flat + sharp + no-accidental signatures add up to 1,974
- Piano: flat + sharp + no-accidental signatures add up to 484
- Guitar: flat + sharp + no-accidental signatures add up to 364
- Voice / choir: flat + sharp + no-accidental signatures add up to 254
- Organ: flat + sharp + no-accidental signatures add up to 155
- Violin: flat + sharp + no-accidental signatures add up to 50
- Strings (ensemble): flat + sharp + no-accidental signatures add up to 37
- Koto / shamisen: flat + sharp + no-accidental signatures add up to 38
- Harpsichord / clavichord: flat + sharp + no-accidental signatures add up to 35
- Brass: flat + sharp + no-accidental signatures add up to 26
- Cello: flat + sharp + no-accidental signatures add up to 15
- Keyboard (unspecified): flat + sharp + no-accidental signatures add up to 18
- Lute / theorbo: flat + sharp + no-accidental signatures add up to 7
- Piano: the key list and the signature table count the same 484 scores
- Piano: listed keys do not exceed the 484 scores
- Guitar: the key list and the signature table count the same 364 scores
- Guitar: listed keys do not exceed the 364 scores
- Voice / choir: the key list and the signature table count the same 254 scores
- Voice / choir: listed keys do not exceed the 254 scores
- Organ: the key list and the signature table count the same 155 scores
- Organ: listed keys do not exceed the 155 scores
- Violin: the key list and the signature table count the same 50 scores
- Violin: listed keys do not exceed the 50 scores
- Strings (ensemble): the key list and the signature table count the same 37 scores
- Strings (ensemble): listed keys do not exceed the 37 scores
- Koto / shamisen: the key list and the signature table count the same 38 scores
- Koto / shamisen: listed keys do not exceed the 38 scores
- Harpsichord / clavichord: the key list and the signature table count the same 35 scores
- Harpsichord / clavichord: listed keys do not exceed the 35 scores
- Brass: the key list and the signature table count the same 26 scores
- Brass: listed keys do not exceed the 26 scores
- guitar: sharps outnumber flats more than four to one; piano: flats outnumber sharps
- C major is the commonest key for both guitar and piano
- four of guitar's five commonest keys (G, D, A, E major) are named after an open string of standard tuning (E A D G B E)
- nine instrument families have at least 20 scores
- guitar and harpsichord are the two families with the highest sharp share
- harpsichord and clavichord scores have a higher sharp share than guitar scores
- string ensembles lean to flats; koto and shamisen scores are almost all without a signature
- the piano's five commonest keys are C, G, F, B♭ major and A minor
- the guitar's five commonest keys are C, G, D, A and E major (up to four sharps)
- at least eight keys are in both instruments' top twelve
- piano scores use more accidentals in the signature on average than guitar scores
- Piano: listed time signatures do not exceed 502 scores
- Guitar: listed time signatures do not exceed 385 scores
- Voice / choir: listed time signatures do not exceed 258 scores
- Organ: listed time signatures do not exceed 173 scores
- Violin: listed time signatures do not exceed 50 scores
- 2/4 is the commonest guitar signature and 3/4 the commonest piano one
- 4/4 is the commonest signature in organ and voice scores
- the Wikipedia excerpt gives the six open-string notes
- the Wikipedia excerpt says guitar music is notated one octave higher than it sounds
Data: The Mutopia Project (per piece: public domain, CC BY or CC BY-SA (only counts are shown here)); Wikipedia (excerpts) (CC BY-SA 4.0). Computed for this site on 2026-10-03; the numbers are counts or shares from the datasets named above, not estimates for music in general. Licences and credits for everything used on this site are on the credits page.