Gdim

Gdim is G, Bb and Db, a diminished triad. The shape this page opens on is written 31x32x, lowest string first.

Note by note. G is the root, Bb is the minor third and Db is the flat fifth.

Also written G°, Go or G diminished. The same chord either way; which spelling you meet depends on who wrote the chart.

There are 5 common shapes for Gdim on the guitar, and 48 derived voicings in the triad family.

One note away. Change a single note of Gdim and you have Gm (with one note moved), Gdim7 (with one note added), Gm7b5 (with one note added) or GmMaj7b5 (with one note added).

In which keys. Every note of Gdim belongs to F minor (the ii°) and Ab major (the vii°).

The common shapes, written lowest string first: 31x32x, xx56x6, x-10-8-x-8-9, x-10-11-12-11-x, 15-13-x-15-14-x.

Under the hand. None of the shapes for Gdim uses an open string, so every one of them is movable; the lowest sits at the 1st fret. None of them needs a barre. Together they cover the neck from the 1st fret to the 15th.

Triad. Three notes across one string set. Gdim has xxx323, x453xx, 3453xx, 645xxx, 6456xx, xx868x, xxx686, xx8686.

Tensions. A shell of Gdim, root, third and seventh, leaves a string free, and the tones that belong over it are the 11 (C) and the b13 (Eb).

What kind of chord this is. Gdim is a diminished chord — root, minor third, flat fifth. diminished and half-diminished chords on every root, and what they are for.

The common shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.