Diminished chord
The diminished triad: a minor third and a diminished fifth above the root. Built from two minor thirds, it sounds tense and unstable. Spelled in all twelve keys, with guitar shapes and piano diagrams.
On C
- Symbol
- Cdim
- Formula
- 1 ♭3 ♭5
- Notes
- 3
- Also written
- C° · Co
What it sounds like
A diminished triad stacks two minor thirds, three semitones each, so its fifth is a diminished fifth, six semitones above the root. That fifth is a tritone, which traditional theory treats as the most unstable interval in tonal music, and it gives the chord its tension. The chord has no perfect fifth, so it does not rest. It leans toward a resolution, and the ear hears its notes as unsettled. The sound is sharp and tense, and the chord usually appears in passing or as a leading-tone chord.
How it is used
In major keys the diminished triad sits on degree 7 as vii°, where the leading tone is the root, and it resolves to I with the root rising a semitone. In minor keys it sits on degree 2 in natural minor as ii°, and on degree 7 in harmonic minor as vii°. The ii° chord often leads to V. Passing diminished chords appear in classical, jazz and pop harmony, moving between two chords whose roots are a step apart.
How it is built
The diminished triad is a root with a minor third and a diminished fifth, 0, 3 and 6 semitones above the root. Common symbols are Cdim, C°, Cm♭5 and Cmin♭5. Built on C, the fifth is G♭, which is the same pitch as F♯, an augmented fourth above C. The inversions are C°/E♭ and C°/G♭. Adding a minor seventh gives Cm7♭5, and adding a diminished seventh gives Cdim7. Each inversion keeps the same three pitches, and only the bass changes.
How to practise it
Build a diminished triad on the seventh degree of C major, which is B, D and F, and play it in each inversion. Then play B, D, F and resolve to C, E, G, moving each voice up by step. In G major the chord is F♯, A, C, which resolves to G, B, D in the same way. Listen to the chord's pull toward the tonic each time.
Diminished chord in every key
Every chord is spelled by letter name. Click a symbol for its page, with inversions and guitar shapes.
| Chord | Notes | Hear it |
|---|---|---|
| Cdim | C E♭ G♭ | |
| C♯dim | C♯ E G | |
| Ddim | D F A♭ | |
| Edim | E G B♭ | |
| Fdim | F A♭ C♭ | |
| F♯dim | F♯ A C | |
| Gdim | G B♭ D♭ | |
| G♯dim | G♯ B D | |
| Adim | A C E♭ | |
| B♭dim | B♭ D♭ F♭ | |
| Bdim | B D F |
Further reading
- Triads and Inversions: Root Position, Sixth, Six-FourHarmony · 6 min
- Diatonic Chords in Major and Minor Keys ExplainedHarmony · 7 min
Questions
What is the difference between a diminished triad and a minor triad?
A minor triad has a perfect fifth, seven semitones above the root. A diminished triad lowers that fifth by a semitone to six semitones, which creates a tritone with the root. Cm is C, E♭, G. Cdim is C, E♭, G♭. The lowered fifth is what makes the diminished triad sound unstable.
How do you write a diminished chord?
Write it as C°, Cdim or Cm♭5. All three name C, E♭ and G♭. The degree sign and dim are the most common forms in printed music, while Cm♭5 appears in some lead sheets. The seventh version is written C°7 or Cdim7.
Why does the diminished triad sound unresolved?
Its tritone, between the root and the lowered fifth, is the most unstable interval in tonal music, and the chord has no perfect fifth to rest on. The ear expects a consonant triad next, so the chord creates a need that the following chord answers.