If I'm playing in C Major the C Major open guitar chord and then I want to play the 5th to this chord, what chord should I play ?

I know there's a rule that says "to determine interval between 2 notes you count from the lowest note to the highest", and I assume that when someone says "give me the 5th of C Major open chord" it means a chord whose root note is a 5th interval apart from the root note C. So, following this logic I can tell that F Major bar chord on 1th fret fits perfectly:

F Major bar chord on 1th fret

since from F on 1st fret of 6th string to C on 3rd fret on 5th string the interval is P5. But, at the same time I can build F Major chord differently, in other words use other voicing:

other F Major voicing

And in this voicing interval between C on 3rd fret of 5th string to the root F on 3rd fret of 4th string is P4.

So, in first voicing the interval is P5 and in second vocing the interval is P4. And the question is: "Who is the real P5 to our C Major" ? Can voicings change the function of the chord (P5 to P4 etc.) ?

  • 1
    A 5th up from C is G, btw [guitar strings are mainly a 4th apart]. I don't actually understand the rest of what you're saying, sorry.
    – Tetsujin
    Commented Mar 31, 2023 at 18:09
  • @Tetsujin, F on 1st fret of 6th string is also 5th from the C (on 3rd fret of 5th string). Which chord considered to be 5th then F or G ?
    – oyevtushe
    Commented Mar 31, 2023 at 18:13
  • 1
    Ah, I see what you're doing - the F is a 5th below the C, which is going to confuse you to start with. For now, always count up, or if you count down, start from 8 & count backwards.
    – Tetsujin
    Commented Mar 31, 2023 at 18:17
  • 1
    Several topics have gotten mixed up here. When we talk about “intervals,“ the context is usually talking about the distance between individual notes, not chords. We also use language like “the fifth of“ when talking about the function of cords within a key, as in “the fifth of C major is G.“ And then we also use it when talking about the notes within the chord itself, in which one of the notes is the “root,“ and the other two notes in a simple cord are the “third“ and the “5th.“ Commented Mar 31, 2023 at 19:35
  • This can't be answered as it stands, as it's asked using skewed facts, and uses distorted information.
    – Tim
    Commented Mar 31, 2023 at 19:51

1 Answer 1


The advice you're working with -- "to determine interval between 2 notes you count from the lowest note to the highest" -- is incorrect. In fact, you can count in either direction and get the same result, but the direction is of course the opposite. If you count up from C to G, you get an ascending perfect fifth. If you count down from G to C you get a descending perfect fifth. In both cases the interval spans five letters (counting inclusively) and seven semitones (not counting inclusively).

On the other hand, if you count down from C to G (or up from G to C) you have changed the interval. (This change is known as "inversion.")

English uses ordinal numbers for intervals and for scale degrees. Because we identify the components of a chord by the interval between the root and the component in question, we also use ordinal numbers to identify them.

As mentioned above, intervals can be either ascending or descending. A perfect fifth above C is G. A perfect fifth below C is F. But because scale degrees and chord components are always identified by the ascending interval, the fifth degree of a C scale is always G. The fifth of a C chord (and of C7, Cm, Cm7, Cmaj7) is always G, regardless of the chord's voicing.

To identify the chord built on the fifth degree of the scale we use a roman numeral, and we speak it as a cardinal number. Therefore, "the V chord" is pronounced "the five chord," and in C major (and C minor for that matter) it is always G, because as described above the fifth degree of the scale is always G.

Therefore, your question

If I'm playing in C Major the C Major open guitar chord and then I want to play the 5th to this chord, what chord should I play?"

... doesn't make a lot of sense, because the fifth of any chord isn't another chord; it's just a single pitch. Since you're asking what chord to play, I suspect that the question is a mistranslation and that it ought to be "...and then I want to play the V chord...," but if it isn't a mistranslation then the second half of the question should be"...what note should I play?"

In the comments, it has been asserted that the major third is so called because it is the third degree of the major scale. While this is not particularly relevant to this question about "fifth" and "five," it seems like a good opportunity to point out that the reverse is true: the major scale is so called because its third degree is a major third. I recently addressed this with respect to major chords in my answer to Why is a minor chord or key considered to be "lesser?"

  • 1
    "you can count in either direction and get the same result" But if you count up three letters in the scale of C you get E, a major 3rd. If you count down three letters you get A. And A-C is a minor 3rd. Because we name intervals by counting up from the lower note, no matter what order the notes are played in. The 'perfect' intervals, 4ths, 5ths and octaves, remain perfect if you count down diatonically. Other intervals don't. Main point - however you arrive it, from below or above - an interval is always NAMED by counting up from the lower note.
    – Laurence
    Commented Apr 1, 2023 at 11:21
  • From what I've understood: 1. the definiton of V chord is bound by scale context, it's not just the 7 half-steps from root notes of chords.
    – oyevtushe
    Commented Apr 1, 2023 at 12:39
  • 2. there's quite an important notion of octave ignorance where we always count from the scale tonic to the note in question, even if notes are in different octaves like F2 and C3, if C is a tonic, then we'll count from C to F and say that F is P4, and it stays P4 no matter the octave it's in (maybe compound intervals add something to this, I didn't think of it yet). So, when we're talking in context of chords and their progression/function in scale, we count intervals this way.
    – oyevtushe
    Commented Apr 1, 2023 at 12:39
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    @phoog And it's called a major 3rd because E is the 3re note of a C major scale. That's just how the system of interval naming works. If the top note's in the major scale starting on the bottom note, it's a major interval. One semitone smaller, it's minor. Another, diminished. One semitone larger, augmented. Special case for the 'perfect' intervals, they contract straight to diminished. We all learnt this in Theory#101. It's a conventional naming system, not deep harmonic analysis.
    – Laurence
    Commented Apr 2, 2023 at 15:31
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    @oyevtushe a perfect fifth is always 7 half steps, but seven half steps isn't always a perfect fifth. It could be a diminished sixth, for example. F is always the 4th degree of the C major scale, but any given F could be a fifth below some given C, or a twelfth below, or an 11th above. The functional role of F in the key of C is typically expressed by IV from its position in the ascending C scale, abstractly, which is why specific voicings don't affect this.
    – phoog
    Commented Apr 2, 2023 at 15:35

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