C♯ diminished seventh (C♯dim7) chord on piano

Diminished seventh chord (three stacked minor thirds) on C♯: the notes of the C♯dim7 chord are C♯ – E – G – B♭. The same chord with a different spelling: D♭ diminished seventh (D♭dim7).

Root position: C♯4 – E4 – G4 – B♭4

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What the C♯dim7 chord sounds like

A diminished seventh is three stacked minor thirds, so it is symmetrical: four different roots give the same notes. A dramatic, tense passing chord.

Notes of the C♯dim7 chord

Degree	Note	Interval from the root
1	C♯	root
3	E	minor third (3 semitones)
5	G	diminished fifth (6 semitones)
7	B♭	diminished seventh (9 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

C♯4 – E4 – G4 – B♭4

1st inversion

E4 – G4 – B♭4 – C♯5

2nd inversion

G4 – B♭4 – C♯5 – E5

3rd inversion

B♭4 – C♯5 – E5 – G5

Which keys is it in?

The C♯dim7 chord is built from the notes of these keys (for minor keys, both the natural and the harmonic minor are considered):

D minor: vii°7

Similar chords and substitutes

If C♯dim7 is too hard, or you want a different colour in the same spot, these chords are worth a try.

Substitutes (by function)

A7 – an incomplete dominant: the diminished chord is the top of this seventh chord
D – where it leads (leading tone → root)

Same notes

Edim7 – the same notes with a different root
Gdim7 – the same notes with a different root
B♭dim7 – the same notes with a different root

Simpler versions

C♯dim – all 3 of its notes are in this chord

Frequently asked questions

What notes are in the C♯dim7 chord?

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

How do I play the C♯dim7 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 C♯dim7 chord written?

The chord symbol is C♯dim7 (also written C#dim7), and its full name is C♯ diminished seventh.