The standard grips this chord is usually shown with.
F#dim7 is F#, A, C and Eb — F#dim with a diminished seventh stacked on top.
It sounds suspenseful and rootless. Three stacked minor thirds divide the octave evenly, so the same four notes spell four dim7 chords and the shape repeats every three frets.

| F# | A | C | Eb |
|---|---|---|---|
| 1 | ♭3 | ♭5 | ♭♭7 |
Leading-tone or passing chord — it can resolve almost anywhere.
Also written F#°7, F#o7 or F# diminished 7. The same chord either way; which spelling you meet depends on who wrote the chart.
F#dim7 in 2nd inversion puts C in the bass instead of F#, the 5th of the chord. The notes are the same; what changes is what the bass line does, which is most of why you would reach for it — it lets the lowest voice move by step where the root would have jumped.
One of F#dim7’s 7 common shapes does this: x-x-10-11-10-11.
Start with 2x121x — no barre and down at the nut. None of the shapes for F#dim7 uses an open string, so every one of them is movable; the lowest sits at the 1st fret. 2 of the 7 need a barre. Together they cover the neck from the 1st fret to the 14th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| 2x121x | 1st fret | F#, root position | C | all fretted |
| 234242 | 2nd fret | F#, root position | F# | barred |
| xx4545 | 4th fret | F#, root position | A | all fretted |
| xx7878 | 7th fret | A, 1st inversion | C | all fretted |
| x-9-10-8-10-8 | 8th fret | F#, root position | C | all fretted |
| x-x-10-11-10-11 | 10th fret | C, 2nd inversion | Eb | all fretted |
| 14-x-13-14-13-14 | 13th fret | F#, root position | F# | barred |
The same notes rebuilt from scratch give 6 shell, 14 drop 2, 9 drop 3 and 1 open string voicings, each on its own page.
Tensions. A shell of F#dim7, root, third and seventh, leaves a string free, and the tones that belong over it are the 9 (G#), the 11 (B), the b13 (D) and the maj7 (E#).
A diminished seventh divides the octave evenly, so F#dim7 has no single root and no single destination: it can lead to B or to G, and it is the same four notes either way.
Every note of F#dim7 is in F# diminished and F# half-whole diminished.
Change one note of F#dim7 and you have F#dim (drop the sixth), F#m6 (the flat fifth becomes a fifth), F#m7b5 (the sixth becomes a flat seventh) or F#mMaj7b5 (the sixth becomes a major seventh).
F#dim7 is a diminished chord — root, minor third, flat fifth. Diminished and half-diminished chords on every root.
On F#dim7’s sound and use this page follows Stefan Kostka, Dorothy Payne & Byron Almén, Tonal Harmony (McGraw-Hill, 8th ed., 2018). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.