Diminished and Augmented Chords: The Other Two Triads
The short answer: There are four triad types, not two. Diminished = a minor chord with the fifth lowered a semitone (1–♭3–♭5). Augmented = a major chord with the fifth raised a semitone (1–3–♯5). Squeezing or stretching the fifth removes the triad's stable frame, so both sound tense and unresolved — which is exactly what they're for: they're the chords that make the next chord feel inevitable.
Built from stacked thirds
Every triad is two thirds stacked up, and the four types are just the four ways to stack major and minor thirds:
| Triad | Stack | Spelling from C/B | Sound |
|---|---|---|---|
| Major | maj 3rd + min 3rd | C–E–G | home |
| Minor | min 3rd + maj 3rd | C–E♭–G | sad home |
| Diminished | min 3rd + min 3rd | B–D–F | anxious, leaning |
| Augmented | maj 3rd + maj 3rd | C–E–G♯ | dreamlike, floating |
Here's B diminished as a compact shape on the top three strings, next to C augmented one fret cluster over:
You already play a diminished chord (sort of)
Harmonize any major scale and the chord built on the 7th degree comes out diminished — in C major, that's B°. It's the answer to "why is the 7 chord weird", and it's why the diminished chord always sounds like it's about to be the I chord: B° is basically a G7 missing its root, and both ache to resolve to C. In real songs, diminished chords mostly work as passing chords between diatonic neighbors — the classic move is I → ♯i° → ii (C → C♯° → Dm), a chromatic stepping stone you'll hear all over jazz standards, gospel, and old pop.
The symmetry party trick
Diminished and augmented triads divide the octave into equal slices — minor thirds (3 frets) and major thirds (4 frets) respectively. Consequence on the fretboard: move a diminished 7th chord shape up 3 frets and you get the same chord, respelled. Move an augmented shape up 4 frets, same deal. No other chords do this. It's why diminished runs sound like a staircase with no floor ("spooky silent-movie chord") and why the same aug shape covers three different chord names — the fretboard economy is absurd.
Augmented in the wild
Rarer than diminished, but unmistakable: the opening chord stab of The Beatles' "Oh! Darling," the James Bond theme's final chord, and the classic I → I+ → vi move ("Baby Hold On") where the fifth creeps up a semitone as a melodic elevator. Augmented chords almost always appear this way — one voice sliding chromatically while the rest hold — rather than as destinations.
Frequently asked questions
What are diminished and augmented chords?
The two triad types beyond major and minor. A diminished chord is a minor triad with the fifth flattened (1-♭3-♭5); an augmented chord is a major triad with the fifth sharpened (1-3-♯5). Both lose the stable perfect fifth that anchors major and minor chords, which is why they sound tense and unresolved.
What's the difference between diminished and augmented chords?
They squeeze the fifth in opposite directions. Diminished lowers it, shrinking the chord and giving it an anxious, "about to resolve" pull. Augmented raises it, stretching the chord into a floating, ambiguous sound. Both are built from equal-interval stacks — diminished from two minor thirds, augmented from two major thirds — which is also why each one repeats itself in a symmetrical pattern up the neck.
What's the opposite of a diminished chord?
An augmented chord, in a specific sense: diminished shrinks the fifth by a semitone, augmented stretches it by a semitone in the other direction. They're the two ways of destabilizing a triad, just pulling opposite ways.