The standard grips this chord is usually shown with.
Adim7 is A, C, Eb and Gb — Adim with a diminished seventh stacked on top.
It sounds suspenseful and rootless. Three stacked minor thirds divide the octave evenly, so the same four notes spell four dim7 chords and the shape repeats every three frets.

| A | C | Eb | Gb |
|---|---|---|---|
| 1 | ♭3 | ♭5 | ♭♭7 |
Leading-tone or passing chord — it can resolve almost anywhere.
Also written A°7, Ao7 or A diminished 7. The same chord either way; which spelling you meet depends on who wrote the chart.
Adim7 in 2nd inversion puts Eb in the bass instead of A, the 5th of the chord. The notes are the same; what changes is what the bass line does, which is most of why you would reach for it — it lets the lowest voice move by step where the root would have jumped.
2 of Adim7’s 8 common shapes do this: xx1212, x-x-13-14-13-14.
Start with x01212 — no barre and 1 open string. 1 of the 8 shapes here sits in open position. 2 of the 8 need a barre. Together they cover the neck from the 1st fret to the 14th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x01212 | open position | A, root position | Gb | 1 open string |
| xx1212 | 1st fret | Eb, 2nd inversion | Gb | all fretted |
| 5x4545 | 4th fret | A, root position | A | barred |
| 567575 | 5th fret | A, root position | A | barred |
| xx7878 | 7th fret | A, root position | C | all fretted |
| x-x-10-11-10-11 | 10th fret | C, 1st inversion | Eb | all fretted |
| x-12-13-11-13-11 | 11th fret | A, root position | Eb | all fretted |
| x-x-13-14-13-14 | 13th fret | Eb, 2nd inversion | Gb | all fretted |
The same notes rebuilt from scratch give 5 shell, 14 drop 2, 9 drop 3 and 1 open string voicings, each on its own page.
Tensions. A shell of Adim7, root, third and seventh, leaves a string free, and the tones that belong over it are the 9 (B), the 11 (D), the b13 (F) and the maj7 (G#).
A diminished seventh divides the octave evenly, so Adim7 has no single root and no single destination: it can lead to D or to Bb, and it is the same four notes either way.
Every note of Adim7 is in A diminished and A half-whole diminished.
Change one note of Adim7 and you have Adim (drop the sixth), Am6 (the flat fifth becomes a fifth), Am7b5 (the sixth becomes a flat seventh), AmMaj7b5 (the sixth becomes a major seventh) or Am/F# (the flat fifth becomes a fifth).
Adim7 is a diminished chord — root, minor third, flat fifth. Diminished and half-diminished chords on every root.
On Adim7’s sound and use this page follows Stefan Kostka, Dorothy Payne & Byron Almén, Tonal Harmony (McGraw-Hill, 8th ed., 2018). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.