Bass · half diminished seventh
C♯m7♭5 Chord on Bass
C# Half-Diminished 7th (m7♭5) is C#, E, G, B — the 1-b3-b5-b7 pattern of a half diminished seventh chord. Here is the shape, the audio, and what usually goes wrong.
There is no open C#m7b5 on bass — the single shape below is a barre, which is exactly why this chord trips people up. Take it slowly and check every string.
Start here — Root-b3-b5-b7 Shape (9th fret)
Barre at fret 9 — the same movable idea, further up the neck: brighter, more compact, and easier to reach if you are already playing up there.
What beginners get wrong
Moving in and out of it
The shape above: Root-b3-b5-b7 Shape (9th fret) — barred at fret 9.
Listening: each shape above has its own play button, and each one plays the notes that shape actually produces — not a generic triad.
C#m7b5 on other instruments
Same notes, different hands. Every link below is a real page with diagrams and audio.
Guitar
C♯m7♭5 on guitar
2 voicings · easiest is intermediate
Piano
C♯m7♭5 on piano
3 voicings · easiest is intermediate
Ukulele
C♯m7♭5 on ukulele
1 voicing · easiest is intermediate
Mandolin
C♯m7♭5 on mandolin
1 voicing · easiest is intermediate
Banjo
C♯m7♭5 on banjo
1 voicing · easiest is advanced
Or see C# Half-Diminished 7th (m7♭5) on every instrument at once.
Chords next door
Same root, different colour — and all of them playable on bass.
C#m7b5 on Bass — questions people ask
What is the easiest way to play C#m7b5 on bass?
“Root-b3-b5-b7 Shape (9th fret)” — which we rate advanced — is the easiest C#m7b5 shape on bass. Barre at fret 9 — the same movable idea, further up the neck: brighter, more compact, and easier to reach if you are already playing up there. There is no open C#m7b5 on bass, so a barre is unavoidable; this is the least demanding one.
What notes are in the C# Half-Diminished 7th (m7♭5) chord?
C# Half-Diminished 7th (m7♭5) is C#, E, G, B — the 1-b3-b5-b7 interval pattern of a half diminished seventh chord. Every voicing on this page uses those notes and nothing else; they just appear in a different order and octave.
What can I play instead of C#m7b5?
The nearest stand-ins on bass that keep the same root are C#m, C#m7, C#dim. They keep the root and the fifth and only change what sits in the middle, so most songs still work — but check the swap against the melody, because the note you removed may be the one the tune is singing.
Can I play C#m7b5 on other instruments?
Yes. C#m7b5 is the same set of notes everywhere; only the fingering changes. This site has diagrams and audio for it on guitar, piano, ukulele, mandolin, banjo.
Learn the theory behind C#m7b5
The shape gets your fingers there. These explain why it sounds the way it does.
Functional Harmony: Three Roles, One Engine
Diminished chords are almost always doing a job. This explains which one.
6 min read
Cadences — The Four Ways a Phrase Ends
Where all that tension goes — how the chord resolves into the next one.
4 min read
Voice Leading — Hold What You Can, Move Only What You Must
Half-steps do the work here. Voice leading is how you find them.
6 min read