Cdim7 chord
Cdim7 is C, E♭, G♭ and B𝄫: 1–♭3–♭5–♭♭7 built on C. See and hear it on all three instruments below.
On guitar
x-3-4-2-4-x · movable · medium
- Notes
- C · E♭ · G♭ · B𝄫
- Formula
- 1 · ♭3 · ♭5 · ♭♭7
- First shape
- x-3-4-2-4-x
Cdim7 on guitar: every shape, finger by finger
On piano
root position · C–E♭–G♭–B𝄫 · right hand 1-2-3-5
- Notes
- C · E♭ · G♭ · B𝄫
- Formula
- 1 · ♭3 · ♭5 · ♭♭7
Cdim7 on piano: fingering and inversions
On ukulele
2-3-2-3 · movable · medium
- Notes
- C · E♭ · G♭ · B𝄫
- Formula
- 1 · ♭3 · ♭5 · ♭♭7
- First shape
- 2-3-2-3
Changing out of Cdim7
The moves below are the ones you'll meet most, shown for guitar and piano.
- Cdim7 → C♯ (leads up a half step)
Guitar: Cdim7 (x-3-4-2-4-x) to C♯ (x-4-6-6-6-4): the index finger lays across the A to high E strings at the 4th fret, your middle finger lands on the D string, 6th fret, move the ring finger to the G string, 6th fret. Nothing carries over, so drill it slowly, lifting and landing all fingers at once.
Piano: Cdim7 to C♯: play C♯ in root position (C♯–E♯–G♯), while C moves up to C♯, G♭ down to E♯ and B𝄫 down to G♯. C♯ - Cdim7 → C♯m (leads up a half step)
Guitar: Cdim7 (x-3-4-2-4-x) to C♯m (x-4-6-6-5-4): the index finger lays across the A to high E strings at the 4th fret, the middle finger goes to the B string, 5th fret, your ring finger lands on the D string, 6th fret. No finger can stay, so practice lifting all of them together and landing the new shape as a unit.
Piano: Cdim7 to C♯m: play C♯m in root position (C♯–E–G♯), while C moves up to C♯, E♭ up to E and B𝄫 down to G♯. C♯m - Cdim7 → F (a fifth down)
Guitar: Cdim7 (x-3-4-2-4-x) to F (1-3-3-2-1-1): the index finger lays across the low E to high E strings at the 1st fret, the middle finger goes to the G string, 2nd fret, your ring finger lands on the A string, 3rd fret. Nothing carries over, so drill it slowly, lifting and landing all fingers at once. Listen for C and B𝄫, which stay put while the rest moves.
Piano: Cdim7 to F: play F in 2nd inversion (C–F–A) and C and A stay under the same fingers, while G♭ moves down to F. F
How Cdim7 is built
Cdim7 is a diminished seventh: three minor thirds stacked, so the chord divides the octave into four equal parts. That symmetry means Cdim7 contains exactly the same four notes as D♯dim7, F♯dim7 and Adim7; which name you use depends on the bass note and the key.
Count keys (black and white) from C: 3 half steps up to E♭, 3 half steps up to G♭ then 3 half steps up to B𝄫.
| Note | Role | Half steps | Hear it |
|---|---|---|---|
| C | root | 0 | |
| E♭ | minor third | 3 | |
| G♭ | diminished fifth | 6 | |
| B𝄫 | diminished seventh | 9 |
Keys and progressions with Cdim7
No major or natural minor key contains Cdim7 as one of its own chords; it turns up as a passing chord on the way somewhere else.
Chords close to Cdim7
- Cdim7 is Cdim plus B𝄫. Cdim
Chords that share most of their notes with Cdim7: D♯dim7, F♯dim7, Adim7, Cdim, D♯dim, F♯dim.
Every C chord
Cdim7 chord: questions
What notes are in the Cdim7 chord?
C, E♭, G♭ and B𝄫. Cdim7 is built 1–♭3–♭5–♭♭7 from C: E♭ is the minor third, G♭ is the diminished fifth and B𝄫 is the diminished seventh.
How do you play Cdim7 on guitar?
The usual shape is x-3-4-2-4-x (movable). All 4 guitar shapes.
How do you play Cdim7 on piano?
Play C, E♭, G♭ and B𝄫 with right-hand fingers 1-2-3-5. C sits just left of the pair of black keys. Inversions and left hand.
How do you play Cdim7 on ukulele?
2-3-2-3 in standard GCEA tuning. More ukulele shapes.
What key is Cdim7 in?
No major or natural minor key contains Cdim7 as one of its own chords; it turns up as a passing chord on the way somewhere else.
What's the difference between Cdim7 and Cdim?
Cdim7 is Cdim plus B𝄫.
Diagrams and sound come from the same data, tested so they match. Updated September 2026.