Sevenths
C♯ half-diminished 7th chord
Dark and unresolved; often the ii chord in a minor key.
C♯m7♭5 is the viiø7 chord in D major. In minor keys: iiø7 in B minor.
- Notes
- C♯EGB
- Formula
- 1♭3♭5♭7
- Built from
- root · minor 3rd · diminished 5th · minor 7th
How to play C♯m7♭5
About the C♯ half-diminished 7th chord
Playing it
On guitar, C♯m7♭5 is one of the friendlier shapes: x42000 needs just two fingers and lets the open strings ring. Don’t strum the low E string.
On piano, C♯m7♭5 has one black key (C♯) and three white keys.
On ukulele the usual C♯m7♭5 shape is 0102, using two fingers.
Related chords
Take away the root and the other three notes form Em (E G B) — so you can think of C♯m7♭5 as Em with C♯ added underneath.
C♯m7♭5 contains exactly the same notes as Em6. Which name fits depends on which note is in the bass and what key you’re in.
Move a single note and C♯m7♭5 becomes a different chord: raise G to G♯ for C♯m7, drop the B for C♯dim and lower B to B♭ for C♯dim7.
