The C diminished seventh chord (Cdim7) is a highly tense and dramatic chord consisting of the notes C, E♭, G♭, and B𝄫, forming a fully diminished seventh chord. Built entirely from stacked minor third intervals, it produces a symmetrical and unstable sound that naturally drives toward resolution. The C diminished seventh chord is widely used in classical, jazz, and cinematic music to create suspense, tension, and dramatic transitions within harmonic progressions. Its unique structure allows it to function as a pivot chord, enabling modulation between keys while adding a rich, dark, and complex tonal color to compositions.
Name: C diminished seventh chord
Symnonyms:: C fully diminished chord
Notes: C, E♭, G♭, B𝄫
Intervals: 1, ♭3, ♭5, 𝄫7
Chord symbol: Co7
Alternative symbols: Cdim7, Cdim, Co
Type: Tetrad (four-note chord)
C diminished seventh chord on the Staff
C diminished seventh chord on Piano
C diminished seventh chord on Guitar
C diminished seventh chord on Ukulele
Rowan Ellis is a musician and educator with a passion for exploring the language of harmony and melody. With years of experience across classical, jazz, and contemporary styles, Rowan breaks down music theory into clear, practical insights. His goal is to make chords and scales less intimidating and more inspiring for every musician.