A#m7b5 is a half-diminished 7th chord, and on the guitar it is played from the notes A#, C#, E, G#. Its first guitar voicing is the open position: low E string open; A string at fret 1 (index finger); D string at fret 2 (ring finger); G string at fret 1 (middle finger); B string at fret 2 (little finger); high e string open. This page is a complete reference for it: notes and intervals, fingerings, mistakes to avoid, the keys it belongs to and a short practice routine.
What notes are in the A#m7b5 chord?
The A#m7b5 chord is a half-diminished 7th chord, and its notes are fixed: A#, C#, E, G#. Every voicing on every instrument uses these same notes, in some order and in some octave — change one of them and you are playing a different chord. The table below lists each note with its interval from the root A#, so you can see the structure of A#m7b5 at a glance. On the guitar, start with the first voicing above and listen for the notes A#, C#, E, G# in A#m7b5.
| Note | Interval |
|---|---|
| A# | Root |
| C# | b3 |
| E | b5 |
| G# | b7 |
The root is A#, the note the chord is named after and the note your ear hears as home. Above it, the intervals in A#m7b5 are b3, b5, b7. Once you know the intervals, you can build A#m7b5 from any root by counting the same semitone steps, which is how the chord works in every key. On the guitar, the notes appear in the order the fingering dictates, but the set of notes never changes.
A#m7b5 sounds dark, jazzy and unresolved — the half-diminished chord is the sound of the ii chord in minor keys. Listen for that character when you play it — if A#m7b5 does not sound that way, one of the notes is probably wrong, and the table above is the place to check. On the guitar, the open position voicing is the place to hear it in A#m7b5.
Comparing A#m7b5 with its closest relatives helps to fix it in your ear. In short, half-diminished against diminished 7th: A#m7b5 keeps the flattened 7th G#; the diminished 7th flattens it further to G. The half-diminished sounds softer and more usable. Practise the two chords back to back and listen to the one note that changes — that single note is the difference between the two chords. On the guitar, start with the first voicing above and listen for the notes A#, C#, E, G# in A#m7b5.
How to play A#m7b5 on guitar
On the guitar, A#m7b5 has 3 voicings in the data below, and each one uses the same notes — A#, C#, E, G# — in a different place on the neck. Start with the first voicing and get it clean before you try the movable shapes further up the neck. Finger numbers below use 1 for the index finger, 2 for the middle finger, 3 for the ring finger and 4 for the little finger, and x means the string is not played.
For the open position, A#m7b5 sits in open position: low E string open; A string at fret 1 (index finger); D string at fret 2 (ring finger); G string at fret 1 (middle finger); B string at fret 2 (little finger); high e string open. This voicing is comfortable because the fretted notes sit close together, from fret 1 to fret 2, so your hand stays relaxed and every note can ring. Strum or pluck it slowly first and check that every note in A#m7b5 — A#, C#, E, G# — sounds, with no buzz and no accidental open string.
The barre chord is the voicing to learn if you want A#m7b5 in open position: low E string muted; A string at fret 1 (index finger); D string at fret 2 (middle finger); G string at fret 1 (index finger); B string at fret 2 (ring finger); high e string open. It barres across strings 2 to 4 at fret 1 with the index finger. The barre is the hard part: the index finger must press every string from 2 to 4 evenly at fret 1, so roll it slightly onto its bony side and keep it close to the fret wire. If the barre buzzes, move it a fraction closer to the fret and press from the arm, not the thumb alone. Strum or pluck it slowly first and check that every note in A#m7b5 — A#, C#, E, G# — sounds, with no buzz and no accidental open string.
Another way to play A#m7b5 is the movable voicing, in around fret 3: low E string at fret 6 (little finger); A string at fret 4 (middle finger); D string at fret 6 (little finger); G string at fret 3 (index finger); B string at fret 5 (ring finger); high e string open. The stretch is the challenge: the fretted notes span from fret 3 to fret 6, so keep your thumb low behind the neck and let your fingers reach rather than squeezing the neck. Strum or pluck it slowly first and check that every note in A#m7b5 — A#, C#, E, G# — sounds, with no buzz and no accidental open string.
Choosing between the voicings of A#m7b5 is a musical decision, not a right-or-wrong one. The open or low-position voicing rings the most and suits strumming, while a barre or movable voicing lets you slide A#m7b5 up the neck to any key without changing the shape. When you change chords, pick the voicing of A#m7b5 that sits closest to the chord before it — shorter moves between shapes mean faster, cleaner changes. Practise the change into A#m7b5 from the chord that comes before it in your song, not the chord on its own, because the move is the skill. On the guitar, the open position of A#m7b5 puts those notes under your fingers in the order the fingering lists them.
A short practice routine for A#m7b5 on the guitar: play the first voicing four times slowly, checking each note, then change to it from the chord a fourth above A# and back, four times, at a slow tempo. Then play the second voicing the same way. If a note buzzes, stop and fix the finger placement rather than playing through the buzz — clean notes at a slow tempo become clean notes at full tempo, while buzzes practised fast become habits. Use the Guitar Chord Finder to see the diagram for A#m7b5 while you practise, and the Chord Finder to compare it with the same chord on other instruments.
Common mistakes
These are the mistakes that most often make A#m7b5 sound wrong on the guitar, and each one has a concrete fix. Work through them one at a time rather than trying to fix everything at once.
Playing a perfect 5th. The 5th must be flattened to E. A perfect 5th turns this into a plain minor 7th chord. On the guitar, the open position of A#m7b5 puts those notes under your fingers in the order the fingering lists them.
Playing the diminished 7th. The 7th here is G#, not G. Flatten it once more and you have the fully diminished chord. On the guitar, start with the first voicing above and listen for the notes A#, C#, E, G# in A#m7b5.
Using it as a tonic. A#m7b5 is a ii chord, not a home chord. It wants to move to the dominant and then resolve. On the guitar, the open position voicing is the place to hear it in A#m7b5.
Burying the flattened 5th. E is the note that defines this chord. If it is muted, the chord collapses into a minor 7th. On the guitar, the open position of A#m7b5 puts those notes under your fingers in the order the fingering lists them.
Where A#m7b5 is used
A#m7b5 is not a diatonic triad in any major or minor key, because it is an extended or altered chord, but its base triad belongs to the key of C# major, the key of F# major, the key of G# major. a passing chord in jazz, leading to a dominant chord and then home. As a dominant-type chord it also points toward D# major, the key a perfect fourth above A#, which is the tonic it most often resolves to. That is where A#m7b5 does its work: not as a home chord, but as a chord that creates movement and then resolves. On the guitar, start with the first voicing above and listen for the notes A#, C#, E, G# in A#m7b5.
Because A#m7b5 is an extended or altered chord, it appears in progressions as a colour or a dominant rather than as a diatonic staple. Try it in place of the plain A# triad in a progression you already know, and listen to how the extra notes change the feel — that substitution is the usual way extended chords enter real music. The Chord Progression Builder lets you try A#m7b5 in a progression in any key and hear how it connects to the chords around it. On the guitar, the open position voicing is the place to hear it in A#m7b5.
The same chord on other instruments is covered in A#m7b5 on piano, A#m7b5 on ukulele, A#m7b5 on bass, and the scales that fit over it are the A# major scale and the A# minor pentatonic scale. Learning A#m7b5 on the guitar and then checking it on another instrument is one of the best ways to fix the notes — A#, C#, E, G# — in your memory, because the notes stay the same while everything else changes.
Practising A#m7b5
A short worked example makes A#m7b5 concrete. Play the four-chord progression D# – A# – Cm – G# in D# major, the key A#m7b5 most often resolves toward: D# – A# – Cm – G#. Play each chord for one bar at a slow tempo, and listen to how A#m7b5 sounds in that sequence — whether it feels like home, like a lift, or like a chord on its way somewhere else. Then play the same four chords in a different order, starting on A#m7b5 itself, and notice how its character changes when it opens the progression instead of sitting inside it. On the guitar, the open position of A#m7b5 puts those notes under your fingers in the order the fingering lists them.
For a second exercise, play A#m7b5 and then the chord a fourth above A#, back and forth, four times each. That move — a chord and the chord a fourth above it — is the most common resolution in Western music, and it is the move A#m7b5 is built for when it acts as a dominant. Finish by playing A#m7b5 on its own, slowly, and naming each note out loud as you play it: A#, C#, E, G#. Naming the notes while you play them is what turns a shape into knowledge you can use in any key. Test yourself with the Practice Chord Quiz and keep time with the Metronome as the tempo rises. On the guitar, the open position voicing is the place to hear it in A#m7b5.
Frequently asked questions
Where is A#m7b5 used?
As the ii chord in minor keys, in the minor ii–V–i progression, and in jazz standards and bossa nova. It almost always leads to a dominant chord. On the guitar, the first voicing above shows where that note sits.
What is the difference between A#m7b5 and A#dim7?
A#m7b5 has the flattened 7th G#; A#dim7 has the double-flattened 7th G. A#m7b5 sounds softer and more usable; the diminished 7th sounds tenser and more dramatic. On the guitar, the first voicing above shows where that note sits.
How do you play A#m7b5 on the guitar?
The first voicing is the open position: frets 0–1–2–1–2–0, fingers 0–1–3–2–4–0, on the guitar. That voicing uses the notes A#, C#, E, G#, and it is the one to learn first. The page above lists more voicings for A#m7b5, so you can choose the shape nearest the chords around it.
Is A#m7b5 hard to play on the guitar?
It depends on the voicing. The first voicing of A#m7b5 on the guitar is the easiest starting point, and the movable voicings further up the neck are harder because they need a barre or a wider stretch. Practise the first voicing cleanly at a slow tempo before you try the others, and the harder shapes will come more easily.
What is the easiest voicing of A#m7b5 on the guitar?
The open position is the easiest voicing listed for A#m7b5 on the guitar: frets 0–1–2–1–2–0, fingers 0–1–3–2–4–0. Learn that shape first, get every note ringing cleanly, and only then move on to the alternative voicings further up the neck.