Power Chord (with octave)
5
0 - 7 - 12Root + perfect 5th + octave
About Power Chord (with octave)
A power chord with an octave is the two-note fifth with the root doubled above it — in C that is C, G and the C an octave higher, still written C5. It carries no more information than the plain power chord and sounds considerably bigger, which is the entire reason it exists.
Notes and formula
The formula is 1 – 5 – 8, or 0 – 7 – 12 in semitones. Three notes, two pitch classes: the added note is the root again, an octave up.
Musically this is still a power chord. There is no third, so the chord is neither major nor minor, and nothing about its harmonic behaviour differs from the two-note form.
What the octave actually adds
Weight. Doubling the root at the octave reinforces the fundamental and every one of its harmonics, so the chord reads as louder and fuller at the same amplifier setting.
It also keeps the chord clear under distortion. The added note shares all its partials with the root, so the extra frequencies distortion produces land on notes already present rather than between them — the same reason the fifth works in the first place.
How to play it
On guitar the shape is the two-note grip with one more finger: x–3–5–5–x–x at the third fret gives C–G–C. Most rock players use this form by default and the two-note version only when the part needs to be lighter.
On the sixth string it is 8–10–10–x–x–x. The shape is movable, identical at every fret, and one of the first things any electric guitarist learns.
When to use the smaller form instead
When the bass is already playing the root an octave or two below, three notes start to crowd the low end. Rhythm parts in dense mixes often drop back to the two-note fifth for exactly that reason.
The three-note form also muddies faster passages: more strings ringing means more time for the previous chord to bleed into the next one.
Why it is not a different chord
Chord symbols describe pitch classes, and adding an octave adds none. Both forms are written C5, and no chart distinguishes them, because the choice belongs to the player and the arrangement rather than to the harmony.
The catalogue lists them separately because the two grips are learned separately and sound different in a mix — but a musician reading C5 is free to play either.
Scales that go with it
All of them, as with any power chord. With no third and no seventh, the chord constrains only the fifth degree.
The minor pentatonic and the blues scale are the usual companions because of the styles that use the chord, not because of anything in the chord itself.
Frequently asked questions
What notes are in a C5 with an octave?
C, G and C an octave above the first. On guitar, x–3–5–5–x–x.
Is it a different chord from a plain power chord?
No. It contains the same two pitch classes and is written the same way. The octave adds weight, not harmony.
Which form should I use?
The three-note one for weight, the two-note one when the bass is already covering the low end or the part is fast. Both are correct readings of C5.