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?

4 Answers 4


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.

enter image description here

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.

  • The notation I know uses underscored C for C contra (then double underscored for subcontra). Dec 27, 2021 at 21:16

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, 2018 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, 2018 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, 2018 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, 2018 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, 2018 at 6:39

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.


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.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.