I noticed that .musicxml used an open g string in guitar as a 3rd octave note. However in classical guitar wouldn't this be the second octave. What octave system does the .musicxml format use?

Or like can you compare the guitar octaves to piano octaves. Like maybe the 3rd guitar octave is the first piano octave. I honestly don't know so any help would be appreciated.

Thanks for your help.

1 Answer 1


The second octave you're referring to is probably the second of the instrument extension.

Guitar is a transposing instrument, and its standard notation should use the "octave clef" (the one with the small 8 under it), meaning that the middle C on a guitar score actually sounds an octave lower.

Note that in computer systems, the first index is 0, not 1, so G3 is actually in the fourth octave.

There are different "standards" for octave numbering in "digital notation" systems, but they usually consider the first (0) octave as the one at the left most of the piano (the one including the lowest A in most 88-keys keyboards), MusicXML seems to use the same reference, since the middle C is considered C4.

  • 1
    Confirmed: MusicXml states under element octave: Octave number: Values: 0 through 9. Octave 4 is octave started by middle C.
    – guidot
    Feb 2, 2021 at 13:53
  • 1
    a.k.a. Scientific pitch notation Feb 2, 2021 at 18:39

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