Cdim chord on piano
The Cdim chord, or C diminished, stacks 3 notes on C: C, E♭ and G♭. Musicians write its formula 1 ♭3 ♭5.
Notes and intervals of Cdim
Each note of Cdim has a job. Counted from the root, you get root (C), minor 3rd (E♭) and diminished 5th (G♭). Change one of these intervals and you get a different chord, which is why the formula 1 ♭3 ♭5 is worth memorising rather than the shape alone.
| Degree | Interval | Note |
|---|---|---|
| 1 | root | C |
| ♭3 | minor 3rd | E♭ |
| ♭5 | diminished 5th | G♭ |
How to play Cdim on piano
Put your right-hand thumb on C, then add the other notes: C, E♭ and G♭. Teachers usually suggest the fingering 1-3-5 (left hand: 5-3-1). Press the keys together, release, and repeat until the chord sounds even.
Inversions of Cdim
An inversion keeps the same notes but puts another one in the bass. Cdim has 2 inversions besides root position: 1st inversion (E♭ G♭ C) and 2nd inversion (G♭ C E♭). Inversions let you move between chords with tiny hand movements, which is how pianists make progressions sound smooth.
Which keys use Cdim?
You find Cdim as a diatonic chord in D flat major (vii°). The most common case is D flat major, where it plays the role of vii°.
Scales to play over Cdim
These scales share every note of Cdim: C blues scale and C Locrian mode. C blues scale is the safest choice; the others add more colour.
About diminished chords
Two stacked minor thirds: 1 ♭3 ♭5. The diminished fifth (a tritone) makes the diminished chord the most unstable triad: tense, dark and restless. It rarely stands alone and pulls towards the chord a semitone above its root. For example Bdim: B D F. Add a diminished seventh and you get the symmetrical diminished seventh chord.
In a major key it sits on vii° (for example Bdim in C major), acting as a lighter V7 that resolves to I. In a minor key it sits on ii°. Passing diminished chords connect neighbouring chords chromatically, for example I ♯i° ii (C C♯dim Dm). Classical music, jazz, ragtime and film scores use it to build suspense.
Root position 1 ♭3 ♭5 sits under fingers 1 3 5. Because it is so unstable, voice-lead it: keep each note within a semitone or a tone of where the next chord's notes are. In classical harmony vii° is often played in first inversion (third in the bass), with that bass note doubled rather than the root.
dim (three notes) and dim7 (four notes, with a diminished seventh) are not the same, though 'dim' on a jazz chart often means dim7. And dim is not m7♭5: the half-diminished chord adds a minor seventh (for example Bm7♭5: B D F A) and sounds much softer. Symbols: ° means diminished, ø means half-diminished.
Frequently asked questions
What notes are in the Cdim chord?
Cdim (C diminished) contains C, E♭ and G♭. In intervals: root (C), minor 3rd (E♭) and diminished 5th (G♭).
How do you play Cdim on piano?
Play C, E♭ and G♭ together with the right-hand fingering 1-3-5. You can also play it in 2 inversions, shown on this page.
What scale goes with Cdim?
C blues scale fits Cdim best. Other scales that contain all its notes: C Locrian mode.
What key is Cdim in?
Cdim belongs to D flat major (vii°). In D flat major it is the vii° chord.
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