The Fdim chord
Built from F - Ab - B, the Fdim is a diminished triad that sounds all leading tone and no rest. It lives at the centre of jazz turnarounds and ragtime piano, and it fits into more keys than most writers expect. What follows below: the voicings worth memorising on guitar and piano, the theory in plain language, progressions in two or three different keys, and a short list of real records that lean on the chord.
Hear the Fdim in the chord builder →Voicings for Fdim
Common ways to grip the Fdim 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 Fdim 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 Fdim
Progressions that use Fdim
Short progressions that put the Fdim 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 Fdim
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 Fdim in the songwriting circle, the natural neighbours when you want a substitution.
Keys where Fdim 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 Fdim 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 Fdim 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 Fdim. For interactive playback, voice-leading hints and substitution suggestions, open the chord builder above.