C Diminished 7th
Cdim7
Notes
C · Eb · Gb · Bbb
Intervals
- RootC (1P)
- Minor 3rdEb (3m)
- Diminished 5thGb (5d)
- Diminished 7thBbb (7d)
Fretboard
On the fretboard, Bb represents Bbb.
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About
The C fully diminished 7 (C–E♭–G♭–B♭♭) stacks four minor thirds, giving it a fully symmetrical structure. Each note can be respelled as a root — C°7 is enharmonically the same chord as E♭°7, G♭°7, and B♭♭°7 — meaning a single shape on the guitar can function as four different leading-tone chords depending on context. This flexibility makes dim7 especially useful as a passing or substitution chord, often resolving up a half step (here to D♭). All four tones carry the chord’s identity; the chord is defined by its symmetry, so removing any note weakens that quality. On guitar, one shape repeats identically every three frets. Compared to Cm7♭5, dim7 is more unstable and dramatically tense.
Similar chords
Chords sharing two or more notes with this one, ranked by overlap.
Scales containing this chord
- C Blues (deg 1)
- B♭ Diminished (deg 2)
- B♭ Harmonic Minor (II)
- B♭ Natural Minor (II)
- D♭ Diminished (deg 8)
- D♭ Harmonic Minor (VII)
- D♭ Major (VII)
- D♭ Melodic Minor (VII)
- E Diminished (deg 6)
- E♭ Diminished (deg 7)
- E♭ Melodic Minor (VI)
- G Diminished (deg 4)
- G Harmonic Minor (IV)
- C Locrian (I)
- A♭ Mixolydian (III)
- E♭ Dorian (VI)
- F Phrygian (V)
- F♯ Lydian (IV)
Scales whose notes include every chord tone. Roman numeral marks the chord root’s position in the scale; dashed badges aren’t linked yet.