A#m7b5 Chord
1st Fret · A-String RootThe standard jazz grip for a half-diminished chord, and the one to learn first. Index on the A string at fret 1 for A#, ring on the D string at fret 2 for E, middle on the G string at fret 1 for G# and pinky on the B string at fret 2 for C# — four notes, one per string, no barre. It is the m7 grip on the A string with the 5th lowered a fret. Let the index tip touch the low E to mute it, and keep the high e out of the strum.
A#m7b5 Chord
6th Fret · E-String RootThe E-string partner to the A-string grip — the pair covers the whole neck between them. Middle finger on the low E at fret 6 for A#, ring on the D string at fret 6 for G#, pinky on the G string at fret 6 for C#, and index on the B string one fret back at 5 for E. The underside of the middle finger mutes the A string and the fingers' pads keep the high e quiet. It is the classic comping shape for the ii chord of a minor ii–V–i.
A#m7b5 Chord
8th Fret · D-String RootFour strings, rooted on the D string — the voicing for when the bass player has the low end. Index on the D string at fret 8 for A#, then middle, ring and pinky side by side on the G, B and high e strings at fret 9 for E, G# and C#. It is the open Dm7b5 shape moved up the neck, with the index standing in for the nut. Mute the low E and A.
Start from A#m7
Play A#m7 and lower the 5th by one fret, to E. Nothing else moves. That single half step is the whole difference, and it is why the chord is written m7♭5.
Half-diminished, not diminished
The bottom three notes — A#, C#, E — are A#dim. Add the minor 7th, G#, and you have A#m7b5. Add a 7th one fret lower instead and you have A#dim7, a different chord. Charts that say "dim" sometimes mean either, so check the notes.
Hear it in a minor ii–V–i
Play A#m7b5 – D#7 – G#m. The half-diminished chord is the ii of G# minor, and that three-chord move is the backbone of minor-key jazz standards and bossa nova. Its C# is also the 7th of D#7, which is why the two chords sit so naturally side by side.
Same notes as two other chords
A#m7b5 contains exactly the same four notes as C#m6 — the bass decides the name — and it is also the top four notes of F#9, played without the root. Every shape on this page keeps A# lowest, so let the root ring.
Slide the grip
The A-string, E-string and D-string shapes use no open strings once they leave the nut, so they slide. Move any one up a fret and you have Bm7b5; down a fret and you have Am7b5.
About the A#m7b5 or B♭m7b5 Chord on Guitar
The A#m7b5 or B♭m7b5 chord — also written A#m7♭5, A#ø7 or A# half-diminished — is built from four notes: A# (the root), C# (the minor 3rd), E (the diminished 5th) and G# (the minor 7th). The formula is 1 – ♭3 – ♭5 – ♭7: a A#m7 chord with the 5th lowered a half step. The bottom three notes form a diminished triad, which is where the name comes from — the triad is diminished but the 7th is not, so the chord is only half-diminished. That lowered 5th makes it restless rather than sad; the chord wants to move, and it almost always moves to a dominant 7th. Its home is the minor ii–V–i, A#m7b5 – D#7 – G#m, the progression at the heart of minor-key jazz, bossa nova and a good deal of pop and neo-soul. It is also the vii chord of B major. Two things it is not: A#dim7, which has a 7th one fret lower, and A#m7, which keeps the perfect 5th. And one thing it is, note for note: C#m6, the same four notes with a different bass. This page covers three voicings: the A-string root grip at fret 1, the E-string root grip at fret 6, and a four-string form rooted on the D string at fret 8. Every diagram is interactive and playable with acoustic guitar sound.
- 013 A#m7b5 chord shapes at intermediate level
- 02Interactive diagrams — click Play to hear each chord
- 03Acoustic guitar sound via audio engine
- 04Built from 4 notes: A#, C#, E and G# (formula 1 – ♭3 – ♭5 – ♭7)
- 05A-string root, E-string root, and D-string root voicings
- 06Difficulty rating on every shape
- 07Free — no sign-up or download needed
ANATOMY
Chord Tones
The 4 notes that form the A# or B♭ Minor 7th Flat 5 chord and their role in the major scale.
Every half-diminished (m7♭5) chord follows this same formula — root, minor third, diminished fifth, minor seventh. A diminished triad with a minor 7th on top, not the diminished 7th of a dim7 chord.
Frequently Asked Questions
Play x-1-2-1-2-x — index on the A string at fret 1 for the root, ring on the D string at fret 2 (E, the ♭5), middle on the G string at fret 1 (G#, the ♭7), and pinky on the B string at fret 2 (C#, the ♭3). Mute the low E and the high e.
A#, C#, E and G# — root, minor 3rd, diminished 5th and minor 7th.
Because only half of it is diminished. A#–C#–E is a diminished triad, but the 7th, G#, is a minor 7th. A fully diminished 7th chord, A#dim7, lowers that 7th one more fret.
As the ii chord in a minor key — A#m7b5 – D#7 – G#m — or anywhere a minor 7th needs more pull toward the next chord. It almost always resolves to a dominant 7th a 4th above, here D#7.