Cdim is a diminished, spelled C, Eb and Gb. In Open G tuning (D2 G2 D3 G3 B3 D4) the easiest shape is x54544, which sits at fret 4, needs a barre across 4 strings at fret 4 and mutes 1 string. 12 positions for it are shown below, from the nut up to fret 11.
Notes and intervals
Note
C
Eb
Gb
Interval
1P
3m
5d
12 ways to play it
Ordered by how hard they are to fret, easiest first, one per position on the neck. Fret numbers are relative to the position marked beside each grid.
x54544sits at fret 4, needs a barre across 4 strings at fret 4 and mutes 1 stringx51514sits at fret 1, needs a barre across 3 strings at fret 1 and mutes 1 stringxx108710sits at fret 7, spans 3 frets and mutes 2 strings108108xxsits at fret 8, needs a barre across 3 strings at fret 8 and mutes 2 stringsxx10111313sits at fret 10, spans 3 frets and mutes 2 stringsx1113111313sits at fret 11, needs a barre across 3 strings at fret 11 and mutes 1 stringx5454xsits at fret 4, needs a barre across 3 strings at fret 4 and mutes 2 stringsxxx544sits at fret 4, needs a barre across 2 strings at fret 4 and mutes 3 strings454544sits at fret 4 and needs a barre across 6 strings at fret 445454xsits at fret 4, needs a barre across 5 strings at fret 4 and mutes 1 stringxx4544sits at fret 4, needs a barre across 4 strings at fret 4 and mutes 2 stringsxx454xsits at fret 4, needs a barre across 3 strings at fret 4 and mutes 3 strings
Keys Cdim belongs to
Cdim is diatonic to 8 of the 96 keys this app knows, playing a different role in each.