Fdim is a diminished, spelled F, Ab and Cb. In DADGAD tuning (D2 A2 D3 G3 A3 D4) the easiest shape is xx3123, which sits at fret 1, 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
F
Ab
Cb
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.
xx3123sits at fret 1, spans 2 frets and mutes 2 stringsxxx10119sits at fret 9, spans 2 frets and mutes 3 strings32642xsits at fret 2, needs a barre across 4 strings at fret 2 and mutes 1 stringx891011xsits at fret 8, spans 3 frets and mutes 2 stringsxx15131415sits at fret 13, spans 2 frets and mutes 2 stringsx8648xsits at fret 4, spans 4 frets and mutes 2 strings686xxxsits at fret 6, needs a barre across 3 strings at fret 6 and mutes 3 strings1511151311xsits at fret 11, needs a barre across 4 strings at fret 11 and mutes 1 string3231xxsits at fret 1, spans 2 frets and mutes 2 stringsxx312xsits at fret 1, spans 2 frets and mutes 3 stringsx2312xsits at fret 1, spans 2 frets and mutes 2 stringsxxx123sits at fret 1, spans 2 frets and mutes 3 strings
Keys Fdim belongs to
Fdim is diatonic to 8 of the 96 keys this app knows, playing a different role in each.