Learn to Play A Half-Diminished 7
What notes are in a half-diminished 7?
The a half-diminished 7 chord (Am7b5) is built from the notes A, C, Eb, G — root, minor 3rd, ♭5, minor 7th.
Am7b5
A diminished triad plus a MINOR 7th: root, ♭3, ♭5, ♭7. Also written m7♭5 — a minor 7 whose 5th collapsed a half step.
How does a half-diminished 7 sound?
Melancholy suspended in mid-air — darker than m7, softer than diminished. The half-diminished chord aches rather than alarms.
The ii chord of minor keys: iiø7–V7–im is THE minor cadence. Its ♭5 already points at the V's 9th, so the resolution feels inevitable.
Where do you use Am7b5?
Aø7 opens the minor cadence: Aø7 → D7 → Gm is THE ii–V–i in G minor — the "Autumn Leaves" move, from bar one.
A shares blues-rock duty with E and D; every jam session eventually lands on an A chord, usually sooner than you expected.
"Autumn Leaves" bar one, "Stairway to Heaven"'s descending line, bossa nova's saddest turns — the gateway chord to sounding like you know jazz.
How do you finger Am7b5 on piano?
The narrow ♭3-♭5 middle packs fingers 2-3 close together: 1-2-3-5 with a consciously relaxed middle of the hand stops the compressed shape from tensing up.
1 of the 4 keys here is black — play those with the longer fingers and keep the wrist level.
Tip: the common mistake
Mixing it up with the fully diminished 7. Half-diminished keeps the MINOR 7th (one half step higher than dim7's ♭♭7) — that single note is the difference between ache and panic.
Reading about A Half-Diminished 7 is step one — recognizing it at speed is the game. Chord Rush drills it until your hands know it.
- ⚡Speed
- ◎Accuracy
- ♪Recognition