C♯dim7: C♯/D♭ Diminished 7th Piano Chord

Root position: either hand, fingers low note to high
Hand	Notes	Fingers
Right	C♯, E, G, B♭	2-3-4-5
Left	C♯, E, G, B♭	5-4-3-2

Scale degree, note, and interval measured from the root.
Degree	Note	Interval from root	Semitones
1	C♯	Perfect unison	0
♭3	E	Minor third	3
♭5	G	Tritone	6
♭♭7	B♭	Major sixth	9

Construction

C♯ Diminished 7th = Root + Minor 3rd + Diminished 5th + Major 6th = C♯, E, G, B♭

Note	Interval	Degree
C♯	Root	1
E	Minor 3rd	♭3
G	Diminished 5th	♭5
B♭	Major 6th	6

Fingering

Note	Key color	Right hand	Left hand
C♯	black	index finger (2)	little finger (5)
E	white	middle finger (3)	ring finger (4)
G	white	ring finger (4)	middle finger (3)
B♭	black	little finger (5)	index finger (2)

Right hand: index finger (2) on C♯, middle finger (3) on E, ring finger (4) on G, little finger (5) on B♭.

Left hand: little finger (5) on C♯, ring finger (4) on E, middle finger (3) on G, index finger (2) on B♭.

C♯ Diminished 7th Inversions

Root position
C♯ – E – G – B♭
1st inversion (C♯dim7/E)
E – G – B♭ – C♯
2nd inversion (C♯dim7/G)
G – B♭ – C♯ – E
3rd inversion (C♯dim7/B♭)
B♭ – C♯ – E – G

Key Signature

A Diminished 7th chord is built from symmetrical or ambiguous intervals, so it doesn't belong to a single key and has no key signature of its own.

Chords in the Key of C♯ Major

These are the triads built on each degree of C♯ Major:

I — C♯ Major (major)

Degree	Numeral	Chord	Quality
1	I	C♯ Major	Major
2	ii	D♯ Minor	Minor
3	iii	E♯ Minor	Minor
4	IV	F♯ Major	Major
5	V	G♯ Major	Major
6	vi	A♯ Minor	Minor
7	vii°	B♯ Diminished	Diminished

Same Notes, Other Names

The notes C♯ – E – G – B♭ aren’t exclusive to this chord. Depending on which note is the bass and how the chord functions, the same pitches also spell the following:

B♭ Diminished 7th→E Diminished 7th→G Diminished 7th→

C♯ Diminished 7th : Frequently Asked Questions

What is the C♯ Diminished 7th chord on piano?

The C♯ Diminished 7th chord contains the notes C♯ – E – G – B♭. On piano, play these notes together to sound the chord.

What is the C# piano chord?

The C# piano chord (written C♯ Diminished 7th) uses the same keys: C♯ – E – G – B♭. The # and ♯ symbols name the same black key.

What notes are in the C# Diminished 7th chord?

C# Diminished 7th is built from the C# root. Check the interactive keyboard above for exact notes and fingering.

How is the C# Diminished 7th chord used in music?

C# Diminished 7th appears in jazz, pop, and classical contexts. Its sound depends on the chord quality (Diminished 7th).

What is the fingering for C# Diminished 7th?

See the fingering chart above. Right hand typically uses thumb on root. Left hand uses pinky on root.

What are the inversions of C# Diminished 7th?

Use the inversion buttons above to see each inversion with notes, fingering, and staff notation.

C♯ Diminished 7th in detail

Exact

Every pitch class is present and nothing outside the chord is added.

Type	Notes	Semitones	Span	Omissions and additions	Set relation
Close, root position	C♯3 E3 G3 B♭3	9	124 mm	none	identical
Close, first inversion	E3 G3 B♭3 C♯4	9	124 mm	none	identical
Close, second inversion	G3 B♭3 C♯4 E4	9	124 mm	none	identical
Close, third inversion	B♭3 C♯4 E4 G4	9	124 mm	none	identical
Drop 2	G2 C♯3 E3 B♭3	15	206 mm	none	identical
Drop 3	E2 C♯3 G3 B♭3	18	248 mm	none	identical
Drop 2 and 4	C♯2 G2 E3 B♭3	21	289 mm	none	identical

Reduced

A subset of the pitch classes: the identity is incomplete rather than altered.

Type	Notes	Semitones	Span	Omissions and additions	Set relation
Shell, root ♭♭7 ♭3	C♯2 B♭2 E3	15	206 mm	omits G	subset
Guide tones, ♭3 and ♭♭7	E3 B♭3	6	83 mm	omits C♯ and G	subset
Rootless close	E3 G3 B♭3	6	83 mm	omits C♯	subset

Spans are measured centre to centre at a 165 mm octave (standard keyboard geometry).

Position	Bass note	Notes in order	Figured bass	Semitones	Span
Root position	C♯	C♯3, E3, G3, B♭3	7	9	124 mm
First inversion: C♯dim7/E	E	E3, G3, B♭3, C♯4	6/5	9	124 mm
Second inversion: C♯dim7/G	G	G3, B♭3, C♯4, E4	4/3	9	124 mm
Third inversion: C♯dim7/B♭	B♭	B♭3, C♯4, E4, G4	4/2	9	124 mm

One position per chord tone in the bass. Spans are for close position: voiced inversions appear under Voicings.

Change one note

Chords a single note away, and what moving that note does.

Chord	Change	Formula	Common tones
C♯dim	drops B♭	1 ♭3 ♭5	3
C♯m7♭5	B♭ becomes B	1 ♭3 ♭5 ♭7	3
C♯m6	G becomes G♯	1 ♭3 5 6	3
C♯m	G, B♭ becomes G♯	1 ♭3 5	2
C♯m7	G, B♭ becomes G♯, B	1 ♭3 5 ♭7	2
C♯mMaj7	G, B♭ becomes G♯, B♯	1 ♭3 5 7	2
C♯6	E, G becomes E♯, G♯	1 3 5 6	2

Frequencies

Note	MIDI	Frequency
C♯3	49	138.59 Hz
E3	52	164.81 Hz
G3	55	196.00 Hz
B♭3	58	233.08 Hz

Reference pitch A440, 12-TET, close root position.

Set theory: prime form, Forte number, interval vector

Absolute pitch class set: {1, 4, 7, 10}
Normal order: [1, 4, 7, 10]
Prime form: (0369)
Forte number: 4-28
Interval vector: <004002>

Pair	Interval	Semitones	Interval class
C♯ to E	Minor third	3	3
C♯ to G	Tritone	6	6
C♯ to B♭	Major sixth	9	3
E to G	Minor third	3	3
E to B♭	Tritone	6	6
G to B♭	Minor third	3	3

Where these facts come from

Every value on this page is derived from the note formula for a diminished 7th applied to the root C♯, using standard music theory. Nothing here is hand-entered per chord, so the notes, intervals, inversions and frequencies cannot drift out of agreement with each other. Pitches assume 12-TET at A440.

C♯ Diminished 7th

Fingerings

C♯ Diminished 7th: notes and degrees