Package leaflet · Information for the musician · Chord

C sharp Half-Diminished Seventh Chord (C♯m7♭5)

Yearning, dark and unresolved. A diminished triad with a minor seventh, softer than a full diminished seventh.

C♯m7♭5
4 notes
x42000

1Composition: what it contains

C♯ – E – G – B

Symbol: C♯m7♭5
Also written: C♯m7♭5, C♯ø, C♯ø7, C♯-7♭5, C♯mi7(♭5)
Formula: 1 ♭3 ♭5 ♭7
Same sound as: D♭m7♭5

Degree	Note	Interval	Semitones
1	C♯	unison	0
♭3	E	minor third	3
♭5	G	diminished fifth	6
♭7	B	minor seventh	10

2Appearance: diagrams and sound

On the guitar

C sharp Half-Diminished Seventh Chord (C♯m7♭5) – guitar chord diagram 1 (x42000) — `x42000`open position

C sharp Half-Diminished Seventh Chord (C♯m7♭5) – guitar chord diagram 2 (x42423) — `x42423`fret 2

C sharp Half-Diminished Seventh Chord (C♯m7♭5) – guitar chord diagram 3 (x4545x) — `x4545x`fret 4

C sharp Half-Diminished Seventh Chord (C♯m7♭5) – guitar chord diagram 4 (9-10-9-9-12-9) — `9-10-9-9-12-9`fret 9

C sharp Half-Diminished Seventh Chord (C♯m7♭5) – guitar chord diagram 5 (x-x-11-12-12-12) — `x-x-11-12-12-12`fret 11

On the ukulele

C sharp Half-Diminished Seventh Chord (C♯m7♭5) – ukulele chord diagram 1 (0102) — `0102`open position

C sharp Half-Diminished Seventh Chord (C♯m7♭5) – ukulele chord diagram 2 (4434) — `4434`fret 3

C sharp Half-Diminished Seventh Chord (C♯m7♭5) – ukulele chord diagram 3 (6777) — `6777`fret 6

On the piano

Piano keyboard

On the staff

Treble clef

On bass and as an arpeggio

Chord tones on the bass neck

Bass pattern: root and fifth

Bass arpeggio

Chord tones on the guitar neck (degrees)

3Indications: what it is used for

The iiø7 chord of a minor key: in a minor ii–V–i it leads to V7(♭9) and then to i. It is also the vii chord of a major key (viiø7), used as a dominant-function chord resolving to I. In jazz it appears in minor ii–V's and as a passing chord; in classical music it is a common pre-dominant. Locrian or Locrian ♮2 is the usual scale. It shares notes with the minor sixth chord built a minor third above its root.

4Dosage: how to practise it

On guitar, learn the shape rooted on the fifth string (the most common), the shape rooted on the sixth string with the fifth string muted, and drop-2 voicings. On piano, play it in all inversions and in the minor ii–V–i progression with smooth voice leading. Practise the minor ii–V–i around the circle of fifths at 70–120 BPM. Arpeggiate 1-♭3-♭5-♭7. Five to ten minutes daily, alternating with the diminished seventh to hear the difference.

5Warnings and common mistakes

Do not confuse m7♭5 (half-diminished) with dim7 (fully diminished): the seventh is minor here and diminished in the dim7. On guitar, check that the fifth is really flat; muscle memory from m7 shapes often keeps a perfect fifth. Do not mix up the symbol ø (half-diminished, slashed circle) with ° (diminished). When improvising, the flat second (♭9) is the avoid note.

6Interactions with chords, scales and keys

Inversions

Inversion 1 · C♯m7♭5/E · E – G – B – C♯
Inversion 2 · C♯m7♭5/G · G – B – C♯ – E
Inversion 3 · C♯m7♭5/B · B – C♯ – E – G

Scales to play over C♯m7♭5

Where it appears (keys and Roman numerals)

7Other presentations available

The same chord from every note

Cm7♭5 Dm7♭5 E♭m7♭5 Em7♭5 Fm7♭5 F♯m7♭5 Gm7♭5 A♭m7♭5 Am7♭5 B♭m7♭5 Bm7♭5

Other chords on C♯

C♯ C♯m C♯dim C♯aug C♯sus2 C♯sus4 C♯5 C♯6 C♯m6 C♯7 C♯maj7 C♯m7 C♯dim7 C♯m(maj7) C♯7sus4 C♯add9 C♯m(add9) C♯6/9 C♯9 C♯maj9 C♯m9 C♯11 C♯m11 C♯13 C♯7♭9 C♯7♯9 C♯7♯5 C♯7♭5

Read this leaflet carefully before playing. Keep it near your instrument. Free to use, print and share for personal and educational use.