Am7b5 A half-diminished seventh chord
- Notes
- A C Eb G
- Formula
- 1 b3 b5 b7
- Semitones
- 0 3 6 10 above the root
- Other symbols
- Aø7, Aø, Am7(b5), Amin7b5
A to C is a minor third (3 semitones), C to Eb is a minor third (3 semitones), Eb to G is a major third (4 semitones). A diminished triad plus a minor seventh, G, so A to Eb is a tritone. It is also called half-diminished: the fully diminished Adim7 has a diminished seventh (9 semitones) instead. With C in the bass the same four keys read as Cm6.
Am7b5 on the piano
Root position from A4: A4, C5, Eb5, G5. Middle C is C4.
Am7b5 on the guitar
Standard tuning (E A D G B E). Strings run low E on the left to high e on the right, frets downwards; × is a muted string, ○ an open string, and each dot shows the note it sounds, with the root in blue-green. Every shape below has A as its lowest note.
x 0 1 0 1 x (low E to high e)
Sounds A2 Eb3 G3 C4
5 x 5 5 4 x (low E to high e)
Sounds A2 G3 C4 Eb4
The E-shape and A-shape grips are movable: an E-shape chord's root is the note under your first finger on the low E string, an A-shape chord's root is the note on the A string. Slide the same grip up or down to play half-diminished seventh chords on other roots.
Inversions of Am7b5
An inversion puts a note other than the root in the bass. The name is what semicord's chord finder calls those notes played bottom to top; a slash name like C/E means a C chord with E in the bass.
| Position | Notes, bass first | Named | Listen |
|---|---|---|---|
| Root position | A C Eb G | Am7b5 | |
| 1st inversion | C Eb G A | Cm6 (also read as Am7b5/C) | |
| 2nd inversion | Eb G A C | Am7b5/Eb | |
| 3rd inversion | G A C Eb | Am7b5/G |
Where Am7b5 fits
Am7b5 is viiø7 in Bb major, iiø7 in G minor. As iiø7 it opens the minor ii–V–i: Am7b5 → D7 → Gm, the minor-key twin of the ii–V–I.