Diminished triad
The diminished triad consists of two minor thirds stacked on top of each other. Its fifth is diminished, that is, reduced by a semitone. It sounds tense and restless, asks for resolution and in major is found on the seventh degree.
- Structure
- minor third + minor third
- Semitone steps
- 0–3–6
- Sign
- small circle (vii°), in chord symbols °
- Example
- B–D–F
Two minor thirds
The page Identify Chords sums up how triads are built: a triad arises when you stack two thirds on a root. Major third plus minor third gives major, minor plus major gives minor, two minor ones give the diminished, two major ones the augmented triad. In semitone steps: major 0–4–7, minor 0–3–7, diminished 0–3–6, augmented 0–4–8.
| Triad | Thirds | Semitone steps | Effect according to the Chords page |
|---|---|---|---|
| Major | major + minor | 0–4–7 | bright, glad |
| Minor | minor + major | 0–3–7 | dark, thoughtful |
| Diminished | minor + minor | 0–3–6 | tense, restless |
| Augmented | major + major | 0–4–8 | floating, hard to place |
Triads compared: minor and diminished on B
On the left Bm (B–D–F♯, perfect fifth), on the right B° (B–D–F, diminished fifth). Only one note distinguishes them: F♯ against F.
The page Chords says: diminished and augmented sound unstable, because their fifth is narrowed or widened, they ask for resolution. Minor and diminished are often confused, because both have a minor third. The difference lies in the fifth: minor has a perfect one, diminished a reduced one. The exercise page advises listening specifically to the top note.
The seventh degree
On the page Diatonic chords the small circle sign is explained: it marks a diminished triad, two minor thirds on top of each other with a diminished fifth. It sounds tense and restless and asks for resolution, mostly to the tonic. In C major that is B° (B–D–F), in the sequence a pull to C.
The triad contains a tritone between root and fifth. The article The leading tone describes how the two notes of a tritone resolve: the B pulls a semitone up to C, the F a semitone down to E.
Common mistakes
- Confusing diminished and minor: Both have a minor third, only the fifth distinguishes them.
- Playing the chord as a point of rest: It demands resolution.
- Overlooking the sign °: It stands for diminished, not for “minor”.
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Related terms
Diminished fifthHalf-diminished seventh chordDiminished seventh chordDiatonic chordTriadTritoneDominant
Editor: Maik Krohm · reviewed on 3 October 2026
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