I am attempting to learn guitar, and I keep coming across this notation in various apps that I've downloaded.

I know that E2 A2 D3 G3 B3 E4 are something to do with tuning, but I'm not exactly sure what.

Can anyone explain what they actually mean and how they might relate to each other and other similar notation?

Also when is it appropriate to use this notation?

2 Answers 2


The letters (E,A,D etc) refer to the note. The standard tuning for the guitar is E,A,D,G,B,E (Last E is two octaves higher than the lowest one).

Now, the numbers after each letter refer to the specific octave (Scientific pitch notation) of the note. As you know, there is more than one note named E. How to tell which one is which? With numbers! The number indicates the note's octave.

Here you can see the different C's:

enter image description here

So, E2 (lowest of your guitar) would be a third above C2 in the image above. A2 would a sixth above the C2 etc.

Generally, if you simply say you tune your guitar to E,A,D,G,B,E (without the numbers), it's the same thing. People with still understand you. But if you want to tell someone the exact octave of a note, you can use the aforementioned numbers. So, being thorough, the exact standard tuning of the guitar is the one you mentioned, which is: E2 A2 D3 G3 B3 E4.

Αs it has been mentioned in the comments, the guitar music is written one octave above than it's played. So, you wouldn't see guitar music in the bass clef.

  • 1
    The only thing missing here is why the guitar sixth string E is E2. That's covered in Andy's reply below... Relative to the piano octave range.
    – RichieHH
    Nov 22, 2018 at 6:39
  • I never knew that was the reason for notation being an octave higher but makes sense
    – Chris
    Feb 27 at 2:58

They're just the "standard" numbers of those notes on a full sized 88 key piano: https://en.wikipedia.org/wiki/Piano_key_frequencies

Interesting note: they run from C to C, not A to A. In other words the numbers start at C, not A. So they run as A0, B0, C1, D1... A1, B1, C2... etc. The octave number increases on the C, not the A. A slightly confusing convention!

  • 4
    Didn't know that! So what names are used for the Bosendorfer with that extra lower octave kept in its box, only to be opened by people who know what they're up to..?
    – Tim
    May 29, 2015 at 9:08
  • 3
    Done a check, and it would appear they're called A-, B-, C- etc.
    – Tim
    May 29, 2015 at 9:23
  • 1
    That's an interesting point, the big 97(?) key piano! I suppose they're so rare very few people have to worry about them. Organs (using the pedalboard) play down in that range though I believe...
    – Andy
    May 29, 2015 at 11:30
  • C in the American notation is a Do note, which is the first note of the C major scale: Do Re Mi Fa Sol La Si Do (next octabe) which is the more basic scale we learn when kids. simplifyingtheory.com/music-scales Jun 6, 2022 at 5:51
  • The “Interesting note” here was so useful! Until I just learned this, the note-number notation always looked illogical to me. Oct 1, 2022 at 7:47

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