Sevenths
A♭ half-diminished 7th chord
Dark and unresolved; often the ii chord in a minor key.
A♭m7♭5 is the viiø7 chord in A major. In minor keys: iiø7 in F♯ minor.
- Notes
- A♭C♭E𝄫G♭
- Formula
- 1♭3♭5♭7
- Built from
- root · minor 3rd · diminished 5th · minor 7th
How to play A♭m7♭5
About the A♭ half-diminished 7th chord
Playing it
On guitar, A♭m7♭5 has an open-position shape, 420102, using four fingers alongside the open strings.
On piano, A♭m7♭5 has two black keys (A♭ and G♭) and two white keys.
On ukulele the usual A♭m7♭5 shape is 1222, using four fingers.
Related chords
Take away the root and the other three notes form C♭m (C♭ E𝄫 G♭) — so you can think of A♭m7♭5 as C♭m with A♭ added underneath.
A♭m7♭5 contains exactly the same notes as Bm6. Which name fits depends on which note is in the bass and what key you’re in.
Move a single note and A♭m7♭5 becomes a different chord: raise E𝄫 to E♭ for A♭m7, drop the G♭ for A♭dim and lower G♭ to G𝄫 for A♭dim7.
Where you’ll hear it
Notice the C♭ in A♭m7♭5 (A♭ C♭ E𝄫 G♭): each note of the chord takes its own letter (A–C–E–G), so the minor 3rd has to be written C♭ rather than B — the same key on a piano, spelled to fit the chord.
