Power Chord Theory

Are they electric or really strong? They're our friends who can rock and they're not Major or Minor players!

View the full lesson at Power Chord Theory | JustinGuitar

Perfect 4ths also sound pretty good with distortion. Pretty sure it’s the way distortion replicates frequency intervals across the spectrum. Could probably sort it out in a day or two with some fourier analysis.


Funnily enough, a 3 string powerchord contains that interval.

If you take a C powerchord you have C to G (the fifth) and G to C (the fourth). Played together the G and C are actually an inverted C5 chord used in many songs such as Smoke on the Water.


You have hit upon a connection between all interval types there @dave.pritchard101

An inverted 5th = a 4th (and vice versa).

An inverted 3rd = a 6th (and vice versa).

Can you see you simple mathematical sum that would allow you to know the inversion for any interval?

Cheers :blush:
| Richard_close2u | JustinGuitar Official Guide & Moderator


I didn’t think of it as an inversion makes sense though.

1 Like

A 5th plays well because its wave frequency is 3:2 of the fundamental. This is the “nicest” ratio after 2:1 (an octave), and it means that the wave of the fundamental and of the 5th constructively interfere after only 2 wavelengths of the root (or 3 wavelenght of the 5th)


There are some folk in the community who understand and appreciate the fundamental physics of wave motion. Thanks for the extra info @Armi

Cheers :smiley:
| Richard_close2u | Community Moderator, Official Guide, JustinGuitar Approved Teacher

I have enough to worry about playing power chords never mind the theory behind them!

1 Like

@Richard_close2u You’re welcome! I love the fundamental aspects of music because this is the reason why, as well as math, this language is universal and the same concepts were achieved independently throughout history

1 Like

In the notes of this lesson it says “While a Major Chord has a root, a major third, and a fifth, a Power Chord consists of only two notes” which I’m guessing is not quite correct based on this lesson https://www.justinguitar.com/guitar-lessons/power-chords-bg-1201 which shows chords with three notes.

1 Like

Hi Stuart,

Happy new year :slight_smile: It actually is correct as the root (or any other note) and its octave(s) are not counted separately. For example, the E5 power chord includes the notes E (root) and B (fifth). There are several ways you can play it, starting from the basic power chord grip with the root note on the 6th string to more elaborate ones like 079900.

1 Like

Happy New Year to you.

Thanks. Just watched the next video in the series which explains this.


Here’s another use of Mr. Cato’s Nifty Key Diagram.

Use whatever memonic you like to come up with the diagram.

Then look :eyeglasses:

Pick any note and call it the root, then the adjacent note on the right it it’s 5th. So if you have a memonic for FCGDAEB, Bob’s your uncle. You have the key to power chord construction.

1 Like

Why thirds may sound worse:
12-tone equal-temperament is kind of bad at approximating the fractions of a perfect third (but is quite good for fourths and fifths).
If you think of a chord being “powerful” when it’s a simple ratio of frequencies, it might explain your feeling.

There’s a cool graphic in the following article: 12 equal temperament - Wikipedia

For someone interested in the mathematics behind it, this could stop me playing guitar for days :slight_smile:

1 Like

The Circle of Fifths does exactly this also (and more). :slight_smile: The Circle of Fifths - where does it come from, where does it go?