Cm7b5 Chord on Guitar
Cm7b5 = C – D# – F# – A# (Root, Minor 3rd, Tritone, Minor 7th)
Cm7b5 — also called C half-diminished — sits in a specific and important harmonic niche: it's the standard ii chord in minor-key jazz progressions, the essential first link in a minor ii-V-i cadence. At the eighth fret, its E-shape barre voicing is one of the more physically involved shapes in this cluster, needing an extra reach for the flattened fifth beyond what a plain minor seventh chord requires.
The notes are C, D#, F#, and A# — root, minor third, diminished fifth, flat seventh — which makes it easy to confuse with a diminished seventh chord on paper, but the two are meaningfully different: a full diminished seventh flattens the seventh twice, while half-diminished flattens it only once, giving m7b5 a smoother, more functional sound that fits naturally into ii-V-i minor cadences rather than existing purely as unstable passing color. In that role — as ii in a minor key — Cm7b5 leads directly into a dominant chord (often altered) before resolving to the i, forming the backbone of countless jazz standards written in minor keys.
Fingerings
Barre (8th fret)
How to Practice It
The diminished fifth demands a stretch beyond what the plain Cm7 shape asks for, similar to the reach the diminished triad needs but layered onto a fuller four-note chord, so isolating that specific finger placement before attempting the whole shape at tempo is worthwhile. Because this chord's real identity comes from its function within a ii-V-i progression, practicing it directly alongside the V and i chords it typically precedes builds a far more useful understanding than learning the shape in isolation ever would.
Common Progressions
- Cm7b5 – F7 – Bbm (ii7b5 – V7 – i, a textbook minor ii-V-i)
- Cm7b5 – F7b9 – Bbm7 (a jazzier version with an altered dominant)
- Cm7b5 – F7 – Bbm6 (resolving the minor ii-V into a colored tonic)
- Dm7 – Cm7b5 – F7 – Bbm (a longer minor-key jazz turnaround)
FAQ
- What's the difference between Cm7b5 and Cdim7?
- Half-diminished (m7b5) flattens the seventh once, giving a flat seventh, while a full diminished seventh flattens it twice, giving a diminished seventh — an interval that's enharmonically the same as a major sixth — making Cdim7 the more symmetrical and unstable of the two despite sharing the same first three notes.
- Why is Cm7b5 called 'half-diminished'?
- It shares the diminished triad's root, minor third, and flattened fifth, but instead of continuing the pattern with a fully diminished seventh, it uses a regular flat seventh instead — 'half' diminished because only part of the chord follows the fully diminished stacking pattern.
- What's Cm7b5's most common harmonic role?
- It functions as the ii chord in minor-key ii-V-i progressions — an essential building block of jazz harmony in minor keys, leading into a dominant chord (often altered) before resolving to the minor tonic.
- Why does this chord need an extra stretch to finger?
- The flattened fifth sits a half step below the perfect fifth a plain Cm7 would use, and reaching that lowered note while keeping the rest of the barre-based shape intact demands more precision and reach than the unaltered minor seventh chord asks for.
- Is Cm7b5 common outside of jazz?
- It's much less common in rock and pop, where plain minor or minor seventh chords are the default, but it does appear in more harmonically ambitious singer-songwriter and film-score writing that wants the specific tension of a ii chord in a minor key.
- How does Cm7b5 lead into a dominant chord in practice?
- As ii in a minor key, it typically moves to V (often with an altered ninth or fifth for extra tension) before resolving to i, following the same functional logic as a major-key ii-V-I but with darker, more chromatically active harmony throughout.
- Does Cm7b5 ever substitute for a diminished seventh chord?
- Occasionally, since the two chords share three of their four notes and both carry unstable, tension-heavy character, but they're not fully interchangeable — m7b5's smoother flat seventh gives it a more functional, less symmetrical role than the fully diminished chord's.
Cm7b5 on other instruments: Cm7b5 on Piano. Related: how chords are built, chord finder.