Cm7b5 C half-diminished seventh chord
- Notes
- C Eb Gb Bb
- Formula
- 1 b3 b5 b7
- Semitones
- 0 3 6 10 above the root
- Other symbols
- Cø7, Cø, Cm7(b5), Cmin7b5
C to Eb is a minor third (3 semitones), Eb to Gb is a minor third (3 semitones), Gb to Bb is a major third (4 semitones). A diminished triad plus a minor seventh, Bb, so C to Gb is a tritone. It is also called half-diminished: the fully diminished Cdim7 has a diminished seventh (9 semitones) instead. With Eb in the bass the same four keys read as Ebm6.
Cm7b5 on the piano
Root position from C4: C4, Eb4, Gb4, Bb4. Middle C is C4.
Cm7b5 on the guitar
Standard tuning (E A D G B E). Strings run low E on the left to high e on the right, frets downwards; × is a muted string, ○ an open string, and each dot shows the note it sounds, with the root in blue-green. Every shape below has C as its lowest note.
x 3 4 3 4 x (low E to high e)
Sounds C3 Gb3 Bb3 Eb4
8 x 8 8 7 x (low E to high e)
Sounds C3 Bb3 Eb4 Gb4
The E-shape and A-shape grips are movable: an E-shape chord's root is the note under your first finger on the low E string, an A-shape chord's root is the note on the A string. Slide the same grip up or down to play half-diminished seventh chords on other roots.
Inversions of Cm7b5
An inversion puts a note other than the root in the bass. The name is what semicord's chord finder calls those notes played bottom to top; a slash name like C/E means a C chord with E in the bass.
| Position | Notes, bass first | Named | Listen |
|---|---|---|---|
| Root position | C Eb Gb Bb | Cm7b5 | |
| 1st inversion | Eb Gb Bb C | Ebm6 (also read as Cm7b5/Eb) | |
| 2nd inversion | Gb Bb C Eb | Cm7b5/Gb | |
| 3rd inversion | Bb C Eb Gb | Cm7b5/Bb |
Where Cm7b5 fits
Cm7b5 is viiø7 in Db major, iiø7 in Bb minor. As iiø7 it opens the minor ii–V–i: Cm7b5 → F7 → Bbm, the minor-key twin of the ii–V–I.