C♯ half-diminished (C♯m7b5) chord on piano

Half-diminished seventh chord (a diminished triad plus a minor seventh) on C♯: the notes of the C♯m7b5 chord are C♯ – E – G – B. The same chord with a different spelling: D♭ half-diminished (D♭m7b5).

Root position: C♯4 – E4 – G4 – B4

Chord finder Transposer

What the C♯m7b5 chord sounds like

The half-diminished (m7b5) chord is a diminished triad with a minor seventh. In a minor key it sits on degree ii – the first chord of the minor ii–V–i.

Notes of the C♯m7b5 chord

Degree	Note	Interval from the root
1	C♯	root
3	E	minor third (3 semitones)
5	G	diminished fifth (6 semitones)
7	B	minor seventh (10 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 – B4

1st inversion

E4 – G4 – B4 – C♯5

2nd inversion

G4 – B4 – C♯5 – E5

3rd inversion

B4 – C♯5 – E5 – G5

Which keys is it in?

The C♯m7b5 chord is built from the notes of these keys (for minor keys, both the natural and the harmonic minor are considered):

D major: viiø7
B minor: iiø7

Similar chords and substitutes

If C♯m7b5 is too hard, or you want a different colour in the same spot, these chords are worth a try.

Substitutes (by function)

A9 – a rootless dominant ninth: the same notes over a root a major third lower
F♯7 – the next chord in a minor ii–V–i (V)

Same notes

Em6 – 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♯m7b5 chord?

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

How do I play the C♯m7b5 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♯m7b5 chord written?

The chord symbol is C♯m7b5 (also written C#m7b5), and its full name is C♯ half-diminished.