Root position
C – Eb – GbThe root C is the lowest note. This is the shape most people learn first.
3 notes · 1 · ♭3 · ♭5
C Diminished Piano Chord (Cdim)
Cdim is built from C, Eb and Gb — the formula 1 · ♭3 · ♭5, or 3 and 6 semitones above C. The shape uses 1 white and 2 black keys, and you can hear it, invert it and compare it below.
Chord
C Diminished
Notes
C · D# · F#Formula
1 · ♭3 · ♭5Right hand
1 · 3 · 5C
D
E
F
G
A
B
C
C#
D#
F#
G#
A#
Choose a chord, then play it. Finger numbers run from thumb (1) to little finger (5).
The finder above already holds Cdim. Press P or the Play chord button to hear C, Eb, Gb sounded together, then change the root or the chord type to compare it with something else.
Chord tones
The notes in Cdim
A diminished triad is two minor thirds stacked on top of each other, which squeezes the fifth a semitone flat. The result is tense and unresolved. It appears on the seventh degree of a major scale and on the second degree of a minor key, and it usually leads straight back to a more stable chord.
| Note | Interval | Degree | Semitones | Right hand |
|---|---|---|---|---|
| Cwhite key | Root | 1 | 0 | 1 · thumb |
| Ebblack key | Minor third | ♭3 | 3 | 3 · middle finger |
| Gbblack key | Diminished fifth | ♭5 | 6 | 5 · little finger |
Step by step
How to play Cdim on piano
- Find C: it is the white key immediately left of every group of two black keys.
- Build upwards from C using 3 and 6 semitones to reach Eb and Gb.
- With the right hand, place finger 1 on C, finger 3 on Eb and finger 5 on Gb. Keep the wrist level and the knuckles rounded.
- Move your hand a little further in towards the fallboard so the black keys sit comfortably under your fingers.
- Play the notes together, then one at a time from the bottom up, and listen to how Cdim settles.
- Try first inversion as well: Eb – Gb – C. Inversions let you change chords without jumping around the keyboard.
Inversions
Cdim in 3 positions
An inversion keeps the same 3 notes and simply moves the lowest one up an octave. Learning them means you can change chords with small hand movements instead of jumping to a new part of the keyboard.
First inversion
Eb – Gb – CEb is the lowest note, so the minor third sits in the bass and the notes below it move up an octave.
Second inversion
Gb – C – EbGb is the lowest note, so the diminished fifth sits in the bass and the notes below it move up an octave.
In context
Which keys contain Cdim
In D♭ major the chord functions as vii°. Altogether it is produced by the scales of 3 keys, so learning it once pays off in several places.
- D♭ majorvii°
- C♯ harmonic minorvii°
- B♭ minorii°
Chord tones are spelled by the degree they occupy, so the third of a minor chord is written as a flat rather than a sharp even though it is the same key on the piano. A double sharp such as F## means the key one whole tone above F.
Compare
Cdim against C minor
Cdim and C minor share C and Eb. Moving the perfect fifth G down 1 semitone to the diminished fifth Gb turns C minor into Cdim.
Practise the pair together: hold the shared notes C, Eb still and move only the one finger. Hearing that single change is the quickest way to recognise the two chords by ear.
Open C minor →Good questions
Cdim questions
What notes are in the Cdim chord?
Cdim contains C, Eb and Gb. Counted from the root, that is the formula 1 · ♭3 · ♭5, or 3 and 6 semitones above C.
What is the right-hand fingering for Cdim?
A comfortable beginner fingering is 1 (thumb) on C, 3 (middle finger) on Eb and 5 (little finger) on Gb. Finger numbers run from the thumb (1) to the little finger (5), and they change once you start using inversions.
How is Cdim different from C minor?
Cdim and C minor share C and Eb. Moving the perfect fifth G down 1 semitone to the diminished fifth Gb turns C minor into Cdim.
Which keys use the Cdim chord?
It occurs naturally in D♭ major (vii°), C♯ harmonic minor (vii°) and B♭ minor (ii°). The roman numeral shows which degree of the key the chord is built on.
What are the inversions of Cdim?
root position is C – Eb – Gb, first inversion is Eb – Gb – C and second inversion is Gb – C – Eb. Every inversion holds the same notes; only the lowest one changes.