B♭ / A♯ half-diminished (m7♭5)
How to play B♭m7♭5 — Half-diminished (m7♭5)
B♭m7♭5 (Half-diminished (m7♭5))B♭ · D♭ · F♭ · A♭
Guitar samples: Acoustic guitar — University of Iowa (via tonejs-instruments, CC-BY 3.0)
B♭ / A♯ half-diminished (m7♭5) — notes and structure
The B♭m7♭5 chord is the half-diminished chord: a minor seventh with a flattened fifth, the key ii chord of minor ii–V–i progressions.
The B♭m7♭5 half-diminished (m7♭5) consists of the notes B♭, D♭, F♭, A♭. Its interval structure is R–3–5–7 — the root, then each chord tone stacked above it. This is the same chord you see in the interactive finder above, drawn on the guitar fretboard with the root circled and every chord tone labelled.
B♭m7♭5 stacks a minor third (D♭), a diminished fifth (F♭) and a minor seventh (A♭) above the root B♭.
The finder shows 2 ways to play B♭m7♭5 — an open-position shape reaching up to the 11th fret. None of them need a barre.
What key is B♭m7♭5 in?
Every note of B♭m7♭5 belongs to the scales below, so the chord sounds at home in each of these keys — the roman numeral is the degree it sits on.
- B major — the vii° chord
- G♯ minor — the ii° chord
Chords that go with B♭m7♭5
In B major, the chords built on the first, fourth and fifth degrees carry most songs — put B♭m7♭5 next to these:
Frequently asked questions
- What notes are in the B♭ / A♯ half-diminished (m7♭5) chord?
- The B♭m7♭5 chord contains the notes B♭, D♭, F♭, A♭. It is the half-diminished chord: a minor seventh with a flattened fifth, the key ii chord of minor ii–V–i progressions.
- How many ways can you play B♭m7♭5 on guitar?
- 2 voicings are shown on this page — from open position up the neck — each with its own fingering diagram and audio.
- Is B♭m7♭5 a hard chord to play?
- It is fairly beginner-friendly — there is an open-position shape and none of the voicings need a barre.
- What key does B♭m7♭5 belong to?
- B♭m7♭5 fits B major (where it is the vii° chord), G♯ minor (where it is the ii° chord) — every note of the chord is in those scales.