Chord · C Diminished
Cdim Chord
Cdim is C, Eb and Gb — tense, unstable; resolves outward.
Cdim on every instrument
The same 3 notes, 6 sets of hands. Open a diagram for alternate shapes, audio and the mistakes to avoid.
What Cdim is made of
Cdim (C diminished) is built from the notes C, Eb, Gb, with the interval pattern 1, b3, b5.
Stack 1, b3 and b5 on a root of C and you get C, Eb and Gb. That interval recipe is what makes the chord a diminished chord — move the same shape to another root and the character travels with it, which is why Ddim sounds like a transposed Cdim.
Diminished: Tense, unstable; resolves outward.
Spelling: the notes above are written the way a score would write them, not simplified to the nearest piano key. That is why this chord is spelled with E♭ rather than its enharmonic equivalent.
Keys that contain Cdim
All 3 notes sit inside the scale of 4 keys. The roman numeral marks the degree the chord is rooted on.
Other chords on C
Same root, different colour.
The same diminished shape, moved
The identical interval recipe, built on other roots.
Questions people ask about Cdim
- What notes are in the Cdim chord?
- Cdim is made of C, Eb and Gb — the 1, b3 and b5 degrees of a diminished chord built on C.
- What keys use the Cdim chord?
- Every note of Cdim belongs to 4 keys: Db Major (vii°), C# Major (vii°), Bb Minor (ii°), A# Minor (ii°). The roman numeral is the scale degree the chord is rooted on.
- How do you play Cdim on guitar and piano?
- This page shows Cdim on guitar, piano, ukulele, bass, mandolin and banjo — 9 voicings in total. Each diagram links to the full instrument page with alternate shapes, audio and common mistakes.
Learn the theory behind it
Why Cdim behaves the way it does — the guides that explain the chord instead of just spelling it.