Fdim

Fdim is F, Ab and Cb, a diminished triad. The shape this page opens on is written xx34x4, lowest string first.

Note by note. F is the root, Ab is the minor third and Cb is the flat fifth.

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

There are 4 common shapes for Fdim on the guitar, and 48 derived voicings in the triad family.

One note away. Change a single note of Fdim and you have Fm (with one note moved), Fdim7 (with one note added), Fm7b5 (with one note added), FmMaj7b5 (with one note added) or Fm/C (with one note moved).

In which keys. Every note of Fdim belongs to Eb minor (the ii°) and F# major (the vii°).

The common shapes, written lowest string first: xx34x4, x86x67, x-8-9-10-9-x, 13-11-x-13-12-x.

Under the hand. None of the shapes for Fdim uses an open string, so every one of them is movable; the lowest sits at the 3rd fret. None of them needs a barre. Together they cover the neck from the 3rd fret to the 13th.

Triad. Three notes across one string set. Fdim has xx310x, xxx101, x231xx, xx3101, 1231xx, x2310x, 423xxx, 4234xx.

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

What kind of chord this is. Fdim 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.