What notes are in a C diminished chord?

C diminished contains three notes: C (the root), E♭ (the minor third), and G♭ (the diminished fifth).

How is C diminished different from C minor?

Only the fifth changes. C minor (C–E♭–G) has a perfect fifth; C diminished (C–E♭–G♭) lowers that fifth a half step. The result sounds tenser and demands resolution.

What does the ° symbol mean?

The ° (degree sign) is the standard chord-symbol notation for diminished. C° means "C diminished triad"; C°7 means "C diminished seventh."

Where does C diminished appear in real music?

Most commonly as a passing chord in flat-side keys, or as the ii° of B♭ minor leading to F major. It's also frequently used as a chromatic neighbour to C major in late-Romantic harmony.

C diminished chord — notes, intervals, and practice

C diminished is built by stacking two minor thirds: C, E♭, G♭. The chord is symmetric in semitones (3 + 3 = 6), and its tritone between root and fifth gives it a distinctly tense, unresolved sound. C° most often appears as the ii° chord of B♭ minor or as a passing chord between diatonic neighbours in flat-side keys.

Intervals

The C diminished chord stacks two thirds on the root. Each interval and its size in semitones:

C→Ebminor 3rd3 semitones
Eb→Gbminor 3rd3 semitones
C→Gbdiminished 5th6 semitones

On the keyboard

Each note of the C diminished chord highlighted on a piano. Pitch class is what matters — any octave works.

On the guitar

One voicing of the C diminished chord on a six-string guitar fretboard.

Common mistakes

The trap with C diminished is the fifth — G♭, not G natural. Replacing G♭ with G voices a C minor chord (C–E♭–G), a much more stable harmony. The diminished fifth is what gives C° its tritone-driven pull. On guitar there's no fully-open voicing; you'll usually see a small barre on the upper four strings or a partial three-string voicing.

In context

C° is the ii° chord of B♭ minor (where it precedes V = F major and resolves to i = B♭ minor) and a common passing chord between B♭ major and D♭ major in chromatic harmony. Bach uses dim triads constantly as transitional sonorities — they're unstable enough to demand resolution but flexible enough to bridge many chord pairs.

Drill it

The C diminished chord is one of 48 in the Chord Trainer. Open the full trainer to practice it alongside related chords with timing and best-time tracking.

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Frequently asked

What notes are in a C diminished chord?: C diminished contains three notes: C (the root), E♭ (the minor third), and G♭ (the diminished fifth).
How is C diminished different from C minor?: Only the fifth changes. C minor (C–E♭–G) has a perfect fifth; C diminished (C–E♭–G♭) lowers that fifth a half step. The result sounds tenser and demands resolution.
What does the ° symbol mean?: The ° (degree sign) is the standard chord-symbol notation for diminished. C° means "C diminished triad"; C°7 means "C diminished seventh."
Where does C diminished appear in real music?: Most commonly as a passing chord in flat-side keys, or as the ii° of B♭ minor leading to F major. It's also frequently used as a chromatic neighbour to C major in late-Romantic harmony.