C♯m7♭5 chord on guitar
C♯m7♭5 (C sharp half-diminished) is a half-diminished chord built on C♯. It has 4 notes, C♯, E, G and B, and its formula is 1 ♭3 ♭5 ♭7.
Notes and intervals of C♯m7♭5
From the root upwards, C♯m7♭5 contains root (C♯), minor 3rd (E), diminished 5th (G) and minor 7th (B). Those intervals give the chord its colour: the formula 1 ♭3 ♭5 ♭7 works the same way in every key, so once you know it for C♯ you can build the chord on any note.
| Degree | Interval | Note |
|---|---|---|
| 1 | root | C♯ |
| ♭3 | minor 3rd | E |
| ♭5 | diminished 5th | G |
| ♭7 | minor 7th | B |
How to play C♯m7♭5 on guitar
The first shape above reads x 4 5 4 5 x from the low E string to the high E string (x means you do not play that string, 0 is an open string), starting at fret 4. The lowest note you play is C♯. The other diagrams show the same chord higher up the neck: pick the one closest to the chords before and after it in your song.
This is a barre or movable shape: keep your index finger straight and close to the fret, and press with the side of the finger rather than the flat pad.
Which keys use C♯m7♭5?
You find C♯m7♭5 as a diatonic chord in D major (viiø7). The most common case is D major, where it plays the role of viiø7.
Scales to play over C♯m7♭5
To improvise over C♯m7♭5, start with C sharp blues scale. All of these scales contain every note of the chord: C sharp blues scale and C sharp Locrian mode. Aim for the chord notes on strong beats and use the other notes to move between them.
About half-diminished chords
A diminished triad plus a minor seventh: 1 ♭3 ♭5 ♭7. Called half-diminished (ø), it is dark and unsettled but softer than a full diminished seventh, because its seventh is minor. It sounds like a question, a sigh that wants to move on. For example Bm7♭5: B D F A.
Its main home is the minor ii-V-i: iiø7 V7 i (for example Bm7♭5 E7 Am). In a major key it sits on viiø7. Jazz, bossa nova and neo-soul use it constantly, and it can also stand in for ivm6 in a minor key, since both chords share the same notes (for example Bm7♭5 and Dm6).
Two movable shapes cover most needs: root on the 5th string (for example Bm7♭5 x2323x) and root on the 6th string with the 5th string muted (for example Bm7♭5 7x776x). Learn each one together with the 7 chord and the minor chord that follow it in a minor ii-V-i, in the same area of the neck.
m7♭5 is not dim7: dim7 has a diminished seventh (A♭ in Bdim7), m7♭5 a minor seventh (A in Bm7♭5). It is not m6 either, although the two share notes: the bass decides. And remember that m7♭5, m7(♭5), -7♭5 and ø7 are all names for the same chord.
Frequently asked questions
What notes are in the C♯m7♭5 chord?
C♯m7♭5 (C sharp half-diminished) contains C♯, E, G and B. In intervals: root (C♯), minor 3rd (E), diminished 5th (G) and minor 7th (B).
How do you play C♯m7♭5 on guitar?
The easiest shape is x 4 5 4 5 x, from the low E string to the high E string, starting at fret 4. This page shows 3 positions with finger numbers.
What scale goes with C♯m7♭5?
C sharp blues scale fits C♯m7♭5 best. Other scales that contain all its notes: C sharp Locrian mode.
What key is C♯m7♭5 in?
C♯m7♭5 belongs to D major (viiø7). In D major it is the viiø7 chord.
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