The F#dim chord
The F#dim (F# - A - C) is a diminished triad, which is why it sounds a passing chord that needs to move. Writers pick it for a moment of unease, and you can find it across early jazz and the Great American Songbook. On guitar the chord sits comfortably under a barre at the second fret; on piano it stacks straight up under the right hand. The page below covers the voicings worth memorising, the theory, the progressions where the F#dim earns its keep, and the records that lean on it.
Hear the F#dim in the chord builder →Voicings for F#dim
Common ways to grip the F#dim on guitar and piano. Guitar diagrams read low E to high E left-to-right; an × means muted, an open circle above the nut means an open string. Filled dots are fretted notes.
Guitar , full chord shapes
CAGED-derived voicings for F#dim across the neck. Pick the shape closest to where your hand already sits.
Guitar , triad shapes
Three-note triad shapes on each string set, shown moving up the neck. Light textures for arpeggios, pop layering and chord-melody work.
Piano voicings
Root position and inversions. The bass note matters: each inversion changes how the chord sits under a melody.
The theory behind F#dim
Progressions that use F#dim
Short progressions that put the F#dim to work. Each one is shown in a different key so you can pick the one that suits your singer.
This chord appears as a borrowed or passing chord in many minor-key progressions.
→ Build this in the chord builderSongs that feature F#dim
Real records where this chord does structural work. No lyrics quoted, just the title and artist so you can pull up a copy and hear it in context.
Related chords
Chords a step away from the F#dim in the songwriting circle, the natural neighbours when you want a substitution.
Keys where F#dim lives
The keys where this chord turns up diatonically. Open any key page for the full set of progressions that lean on it.
Related references
Other ways to put the F#dim to work across the reference library.
More songwriting tools
Got the chord but still wrestling with the lyric? Find the right rhyme in RhymeForge, or break a writer's block with the unexpected word-pair generator in CollisionLab. Need to map a full progression? The chord builder on the home page is where the F#dim fits into context. All free, no signup.
About the chord builder
The Undercover Zest chord progression builder is a free interactive tool that maps every diatonic and borrowed chord in every key. Click a Roman numeral to hear it, drag chords into a progression, then audition voicings, inversions and tensions until the song clicks.
This page is a static reference for the F#dim. For interactive playback, voice-leading hints and substitution suggestions, open the chord builder above.