The standard grips this chord is usually shown with.
Gdim7 is G, Bb, Db and Fb — Gdim 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.

| G | Bb | Db | Fb |
|---|---|---|---|
| 1 | ♭3 | ♭5 | ♭♭7 |
Leading-tone or passing chord — it can resolve almost anywhere.
Also written G°7, Go7 or G diminished 7. The same chord either way; which spelling you meet depends on who wrote the chart.
Gdim7 in root position puts G in the bass, which is the chord as it is spelled: the note it is named after underneath everything else.
6 of Gdim7’s 8 common shapes do this: 31x320, 3x2320, 345353, xx5656, x-10-11-9-11-9, 15-x-14-15-14-15.
Start with 31x320 — no barre and 1 open string. 2 of the 8 shapes here sit in open position. 2 of the 8 need a barre. Together they cover the neck from the 1st fret to the 15th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| 31x320 | open position | G, root position | Fb | 1 open string |
| 3x2320 | open position | G, root position | Fb | 1 open string |
| 345353 | 3rd fret | G, root position | G | barred |
| xx5656 | 5th fret | G, root position | Bb | all fretted |
| xx8989 | 8th fret | Bb, 1st inversion | Db | all fretted |
| x-10-11-9-11-9 | 9th fret | G, root position | Db | all fretted |
| x-x-11-12-11-12 | 11th fret | Db, 2nd inversion | Fb | all fretted |
| 15-x-14-15-14-15 | 14th fret | G, root position | G | barred |
The same notes rebuilt from scratch give 6 shell, 14 drop 2, 10 drop 3 and 1 open string voicings, each on its own page.
Tensions. A shell of Gdim7, root, third and seventh, leaves a string free, and the tones that belong over it are the 9 (A), the 11 (C), the b13 (Eb) and the maj7 (F#).
A diminished seventh divides the octave evenly, so Gdim7 has no single root and no single destination: it can lead to C or to Ab, and it is the same four notes either way.
Every note of Gdim7 is in G diminished and G half-whole diminished.
Change one note of Gdim7 and you have Gdim (drop the sixth), Gm6 (the flat fifth becomes a fifth), Gm7b5 (the sixth becomes a flat seventh) or GmMaj7b5 (the sixth becomes a major seventh).
Gdim7 is a diminished chord — root, minor third, flat fifth. Diminished and half-diminished chords on every root.
On Gdim7’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.