Cdim is a diminished, spelled C, Eb and Gb. In Standard tuning (E2 A2 D3 G3 B3 E4) the easiest shape is x3454x, which sits at fret 3, spans 2 frets and mutes 2 strings. 12 positions for it are shown below, from the nut up to fret 13.
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.
x3454xsits at fret 3, spans 2 frets and mutes 2 strings231xxxsits at fret 1, spans 2 frets and mutes 3 stringsxxx542sits at fret 2, spans 3 frets and mutes 3 stringsxx454xsits at fret 4, needs a barre across 3 strings at fret 4 and mutes 3 strings89108xxsits at fret 8, needs a barre across 4 strings at fret 8 and mutes 2 stringsxxx878sits at fret 7, spans 1 fret and mutes 3 strings1191011xxsits at fret 9, spans 2 frets and mutes 2 stringsxx10111311sits at fret 10, spans 3 frets and mutes 2 stringsxx13111311sits at fret 11, needs a barre across 3 strings at fret 11 and mutes 2 strings86108xxsits at fret 6, spans 4 frets and mutes 2 strings141513xxxsits at fret 13, spans 2 frets and mutes 3 stringsx6454xsits at fret 4, needs a barre across 3 strings at fret 4 and mutes 2 strings
Keys Cdim belongs to
Cdim is diatonic to 8 of the 96 keys this app knows, playing a different role in each.