The Cdim chord
Think of the Cdim as the ragtime piano grease. The chord is built from C - D# - F#, a textbook diminished triad. It does its strongest work in early jazz and the Great American Songbook, where it tends to walk between two diatonic chords. The Cdim stays useful for years. A passing chord between two stable major chords. Ragtime piano lives on it. Voicings on both instruments, theory in plain language, progressions in multiple keys and a handful of real song references are all laid out below.
Hear the Cdim in the chord builder →Voicings for Cdim
Common ways to grip the Cdim 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 Cdim 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 Cdim
Progressions that use Cdim
Short progressions that put the Cdim 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 Cdim
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.
- My Funny Valentine by Standard. Cdim as a passing chord between two diatonic chords.
- Sweet Georgia Brown by Standard. Cdim within the ragtime turnaround.
- Take the A Train by Duke Ellington. Cdim colour in the verse.
Related chords
Chords a step away from the Cdim in the songwriting circle, the natural neighbours when you want a substitution.
Keys where Cdim 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 Cdim 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 Cdim 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 Cdim. For interactive playback, voice-leading hints and substitution suggestions, open the chord builder above.