Chord Theory: Augmented Chords

This week, we’ll continue our study of chord theory with an explanation of augmented chords. This article assumes that you’ve read the articles below, so read them if you haven’t already.

One Step at a Time
Intervals: your tape measure for music
Chord Theory: Triads
Chord Theory: Power Chords
Chord Theory: Major Chords
Chord Theory: Minor Chords
Chord Theory: Diminished Chords
Chord Theory: Suspended Chords

Augmented chords have an unbalanced, suspenseful sound due to their non-diatonic, atonal construction. So far, we’ve been discussing major, minor, diminished and suspended chords. All of those chords are diatonic because they appear naturally in the major scale, or diatonic, system. Augmented chords are atonal because they aren’t diatonic; they do not appear in any major key. Let’s find out why.

The augmented chord has an unusual recipe: major third + major third:

Root + major third = Third
Third + major third = Augmented (or sharp) Fifth

I often compare an augmented to chord to a diminished chord to help me remember the recipes of each. A diminished chord has a recipe of minor third + minor third, whereas an augmented chord has a recipe of major third + major third. They are almost like opposites.

As you can see from the recipe, an augmented chord can be thought of as a major chord with sharpened fifth. Many musicians think about the augmented chord this way.

Alright, let’s build an augmented chord on the fretboard. We’re going to create a C augmented chord and relate it to the C major chord. First, let me remind you that a C major chord has the notes C, E and G in it. If I’m correct that an augmented chord is like a major chord with a sharpened fifth, then a C augmented chord should have the notes C, E and G♯. Let’s look at a C major chord first:

Notice the perfect fifth between the root and the fifth of the C major chord. Now, let’s create a C augmented chord:

Take note of how the fifth is now sharpened, or augmented, because of the major third + major third recipe. All we need to do now is move our C, E and G♯ to separate strings so we can play them simultaneously. I’ll use my knowledge of the fretboard to find suitable places for them:

Augmented chords are rare in popular music, but they can be very effective as substitutions for the V chord. If you’re looking to set your audience off balance for a moment, the augmented chord is the way to go. It’s atonal sound resolves nicely.

Now about that atonal sound. I mentioned at the beginning of the article that augmented chords don’t appear naturally in the major, or diatonic, system. The reason is that the augmented fifth found in the augmented chord never appears in any key. The major key interval pattern (whole step – whole step – half step – whole step – whole step – whole step – half step) doesn’t produce an augmented fifth, therefore an augmented chord will sound atonal, or outside the key.

This article covers the last of the triads. I’ll let you digest all of the information that I’ve given you over the last six weeks. When I resume, we’ll investigate seventh chords.

Next week, I’ll summarize all of the material we’ve covered up to now.

For more information about me and the guitar lessons that I give in and around Baltimore, visit

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