Power Chord

Notes and formula

The formula is 1 – 5, or 0 – 7 in semitones. Two notes, sometimes three when the root is doubled an octave above, which is written the same way and sounds fuller without adding any new information.

A perfect fifth is the simplest interval after the octave — a 3:2 ratio — and the two notes share most of their upper partials. That is what makes the chord sound like a single thickened note rather than a harmony, and it is why bass and guitar can play it together without the result turning muddy.

Why distortion made it necessary

Distortion adds new frequencies at the sums and differences of everything already sounding. Two notes a fifth apart produce sums and differences that mostly land on notes already in the chord; a major third added to the pair produces a thicket of intermediate tones that the ear reads as dirt.

This is a measurable acoustic fact rather than a matter of taste, and it explains the entire history of the chord: as amplifiers got louder and dirtier through the nineteen-sixties, thirds disappeared from rock rhythm playing and fifths took over. Link Wray's Rumble in 1958 is the usual first citation, the Kinks and the Who made it standard, and Black Sabbath built a genre on it.

How to play it

On guitar C5 is x355xx, with the root on the fifth string and the fifth on the fourth. The same two-finger shape works at every fret and on every string pair, which is why it is usually the first movable chord a rock guitarist learns.

Adding the octave gives x355xx with the third string fretted as well — a three-note version that is louder and heavier without being a different chord. Playing the fifth below the root instead gives the inverted form, which sounds thinner and is easier to reach at the bottom of the neck.

What it does in a progression

Because it has no third, it borrows quality from whatever surrounds it. A riff of fifths over a minor-key bass line sounds minor; the same shapes over a major-key melody sound major. Guitarists exploit this to play riffs that would need two different fingerings if the thirds were spelled out.

It also removes the need to think about modes. A progression of power chords can move anywhere on the neck without producing a wrong note, which is why so much rock harmony is built on parallel fifths — a motion that classical part-writing forbids outright.

Is it really a chord

Strictly a chord has three or more distinct notes, so a two-note power chord is a dyad. The name stuck anyway because the sound occupies the role a chord occupies: it defines the harmony of a bar and it is strummed, not played as a melodic interval.

Notation reflects the compromise. C5 is written as a chord symbol, sits in chord charts alongside triads, and is read by every player as an instruction to leave the third out.

Scales that go with it

Any of them. With no third and no seventh, the chord constrains nothing except the fifth degree, so major and minor pentatonics, the blues scale and every mode with a perfect fifth all fit.

In practice the minor pentatonic and the blues scale are the usual companions, because the styles that use power chords most also grew out of blues phrasing. That pairing is a habit of genre, not a requirement of the chord.

Frequently asked questions