C diminished (Cdim) chord on piano

Diminished triad (two minor thirds) on C: the notes of the Cdim chord are C – E♭ – G♭.

Root position: C4 – E♭4 – G♭4

What the Cdim chord sounds like

A diminished triad is two stacked minor thirds with a diminished fifth. It sounds tense and unsettled; in a major key it sits on degree vii and leads into the tonic.

Notes of the Cdim chord

Degree	Note	Interval from the root
1	C	root
3	E♭	minor third (3 semitones)
5	G♭	diminished fifth (6 semitones)

Root position and inversions

An inversion uses the same notes, with a different note at the bottom. When you change chords, choosing the nearest inversion keeps your hand almost still.

Root position

C4 – E♭4 – G♭4

1st inversion

E♭4 – G♭4 – C5

2nd inversion

G♭4 – C5 – E♭5

Which keys is it in?

The Cdim chord is built from the notes of these keys (for minor keys, both the natural and the harmonic minor are considered):

D♭ major: vii°
B♭ minor: ii°

Similar chords and substitutes

If Cdim is too hard, or you want a different colour in the same spot, these chords are worth a try.

Substitutes (by function)

A♭7 – an incomplete dominant: the diminished chord is the top of this seventh chord
C♯ – where it leads (leading tone → root)

Richer versions

Cdim7 – the same chord plus 1 colour note
Cm7b5 – the same chord plus 1 colour note

Frequently asked questions

What notes are in the Cdim chord?

C, E♭, G♭. The root is C; the intervals of the other notes from the root: minor third, diminished fifth.

How do I play the Cdim chord on piano?

In root position, the right hand usually plays with fingers 1, 3 and 5 (thumb, middle finger, little finger); four-note chords with fingers 1, 2, 3 and 5. The left hand mirrors this: 5, 3, 1. In an inversion the top or bottom note moves to the other side, so your hand moves less when you change chords.

How is the Cdim chord written?

The chord symbol is Cdim, and its full name is C diminished.