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I know you say the A above Middle C when refering to the A that is in the same Octave as Middle C in the Treble Staff, or you say the A below Middle C when referring to the A in the previous Octave on the Bass Staff, but what about if you're referring to the A in the next or previous Octave and so on? Do you say two As above Middle C or two As below Middle C or something like that?

30

This is an issue of what we call octave designation.

There is actually an international standard here: called International Pitch Notation (IPN), it labels Middle C as C4. An octave above Middle C is C5, an octave below Middle C is C3, etc.

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In short, the C's octave range is in play until the next C changes the octave register. In other words, from C3 to B3 is all X3; it's not until C4 that pitches enter the X4 octave.

The G below Middle C, for instance, is G3, because it's within the C3 to B3 range. The G at the top of the treble clef will be G5.

Lastly, sometimes accidentals can be a little tricky. Imagine the B♯ that's enharmonic to Middle C. It's raised from B3, but it's enharmonic to C4. In this case, we focus on the note name. Since it's a chromatic alteration of B3, it's B♯3, even if it's enharmonic to C4.


I should also mention another system, that of Helmholtz notation, which uses a mixture of capital/lowercase letters and sub/superscript slashes:

enter image description here

It functions in a very similar way that the above IPN does, it's just a different labeling system.

In my experience, C4 as Middle C is very much the standard.

  • As ever, an accurate, clear answer. +1. – Tim Mar 30 '18 at 7:39
  • Why is C4 not in the same c-to-c range has A4 (440hz standard)? – watchme Mar 30 '18 at 10:25
  • 2
    I think I have realized that my guitar is one octave below the notes I am playing – watchme Mar 30 '18 at 10:40
  • @Richard Perhaps I have misunderstood your comment but isn't A440 A4? You appear to be saying that it is A5 – JimM Mar 30 '18 at 14:27
  • @JimM Oh, I'm a moron. A440 is A4, my brain just wasn't working for a split second. Thanks! – Richard Mar 30 '18 at 14:30
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In addition to Richard's answer you might also consider MIDI note designations which work similarly. In MIDI there are 128 notes split into 10 octaves that start with C0 (#0) and going to G10 (#127) with every octave designation starting on C and moving up every 12 notes. This would put middle C at C5 (#60) rather than C4, and in IPN that makes octave 0 into octave -1. Of course, a normal 88 key piano can only play from note #21 (A1) to note #108 (C9), but if you're looking to compose using the computer can can be helpful to know these designations.

  • Referring to middle C as MIDI note #60 would seem reasonable, but I don't think MIDI octave numbers would be used except perhaps in some MIDI transcription programs. Even there, I think note #12 is the lowest valid C note in MIDI. – supercat Mar 30 '18 at 3:44
  • @supercat could you clarify more on "note #12 is the lowest valid C note is MIDI"? Looking at the table listed here, there's #0 for C-1. And as explained further, the lowest octave number can vary from -2 to 0. But still, MIDI note #0 is valid. – Andrew T. Mar 30 '18 at 5:16
  • @AndrewT.: It's been decades since I got my first MIDI keyboard and software, but I thought I recalled something using a note value of 0 as having a special meaning. Maybe it's only a velocity of zero that's special. Mea culpa if so. In any case, i suspect 60 was chosen as middle C because it's closest to the middle of the 0-127 range, rather than because there were actually 5 usable octaves above and below it. If C5 were 256Hz (a bit below concert pitch), C0 would be 8Hz and C10 would be 8192Hz. Rather extreme frequencies. – supercat Mar 30 '18 at 5:43
  • @supercat ah, I think I understood the underlying issue. Actually, the MIDI note itself doesn't mean anything in term of frequency. The underlying instrument/VST that plays the MIDI note is the one that controls how to play each note. An example with piano would be not playing any sound for notes <A1 or >C9. However, MIDI is also used for making drum sounds, or even sound effects. C0 on those "instruments" won't play "8Hz" ;) – Andrew T. Mar 30 '18 at 6:05
  • @supercat That's kind of the point of MIDI. I think more importantly MIDI data is encoded in 8-bit so having 128 notes gives you half the values that 8 bits provides. Sub frequencies can be utilized by some speaker systems, most likely for bass drums, but as Andrew says the pitches aren't bound by frequency so you could use a different tuning too. – Tama Mar 30 '18 at 6:39
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Sometimes there is benefit in losing some precision for the sake of simplicity. There are lots of good answers here but in rehearsal and when talking to students I find myself using a simpler way of communicating which octave I mean. I believe I learnt this from my first piano teacher.

The C in between the treble and bass clefs is middle C; the C in the middle of the treble clef is Treble C; the C in the middle of the bass clef is Bass C. There C on ledger lines above the treble clef is High C, the one below the bass clef is Low C. This gets 5 octaves which works well for voice and most instruments, especially in early levels.

To refer to non-C notes, I use above and below referring to the nearest C, so "the F above Low C" or "the G below Treble C."

I find this the easiest for spoken communication especially with students I work with a lot. For writing I generally default to IPN in Richard's answer.

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If you'd like to name a note relative to middle C, it would probably be "2nd A above/below middle C". Many articles on English Wikipedia provide this kind of naming together with International Pitch Notation one.

Middle C is C4 in IPN so its octave can be called "fourth". However some MIDI-related software shift octave numbers up by one (probably because MIDI note 0 is C-1 and they want to display it as "C0" instead), for example middle C is "C5" in FL Studio. Some electronic keyboards have the opposite shift and middle C is labeled "C3" on them. This variation can lead to confusion.

Helmholtz notation provides different octave names. From middle C and up octaves are one-line (or once-accented), two-line (or twice-accented) and so on. Octaves below (from higher to lower) are called small, great, contra, sub-contra. No number variations, but naming of lower octaves isn't very intuitive.

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