Learn › C Diminished 7th Chord on Piano (Cdim7)
New Released in April 2026
C Diminished 7th Chord on Piano (Cdim7)
C diminished 7th (Cdim7) is spelled C - Eb - Gb - Bbb. It sounds like Cdim with an extra Bbb, the note that gives it its tense, dramatic colour. Here you will find its inversions, both hands and the chords it belongs with.
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- MIDI keyboard
- Digital or acoustic piano
- Guitar
- Computer, phone or tablet
Cdim7 fingering, both hands
| Hand | C | Eb | Gb | Bbb |
|---|---|---|---|---|
| Right hand | 1 (thumb) | 2 | 3 | 5 (little) |
| Left hand | 5 (little) | 3 | 2 | 1 (thumb) |
Play Cdim7 broken first, C, Eb, Gb, Bbb one by one, then together: a wrong key stands out.
Cdim7 without the fifth
The fifth (Gb) adds little colour. C Eb Bbb is enough to sound like Cdim7 and is far easier to reach.
A 5-minute Cdim7 routine
- Play C, Eb, Gb, Bbb slowly in root position and say "Cdim7" each time.
- Climb the four positions: C Eb Gb Bbb, then Eb Gb Bbb C, Gb Bbb C Eb and Bbb C Eb Gb, and back down.
- Loop Cdim7 → C#m until the change into and out of Cdim7 is clean.
- Then mix it with chords you already know, in an order you do not choose: that is where it sticks.
A few minutes every day on Cdim7 beat one long session a week.
Cdim7 compared with the other 7th chords on C
Same root, same fifth: watch the third and the seventh.
Four ways to play Cdim7
A seventh chord has four notes, so it has four positions. Each one is still Cdim7.
Root position: C Eb Gb Bbb
1st inversion: Eb Gb Bbb C
2nd inversion: Gb Bbb C Eb
3rd inversion: Bbb C Eb Gb
What Cdim7 does in music
- Cdim7 is the vii°7 chord of C# minor: it pulls up one key, Cdim7 → C# / C#m.
- Every note is three keys above the one before, so Cdim7, Ebdim7, F#dim7 and Adim7 use the same four keys.
- That even spacing is why Cdim7 sounds tense, dramatic and can lead to several different chords.
- Bbb is the same key as A.
vii°7 → i: Cdim7 → C#m
Practise Cdim7 by playing
Knowing Cdim7 on paper is step one. ChordRunner makes you find it fast, mixed with other chords. MIDI keyboard or microphone, both work.
Play the demoCommon questions
How do you play Cdim7 on the piano?
Press C, Eb, Gb, Bbb together. Right hand 1, 2, 3, 5 with the thumb on C; any octave and any order of those notes is still Cdim7.
What are the inversions of Cdim7?
Root position C Eb Gb Bbb, 1st inversion Eb Gb Bbb C, 2nd inversion Gb Bbb C Eb and 3rd inversion Bbb C Eb Gb. Every position is still Cdim7.
Where does Cdim7 go?
Cdim7 is the vii°7 chord of C# minor: it pulls up one key, Cdim7 → C# / C#m. Every note is three keys above the one before, so Cdim7, Ebdim7, F#dim7 and Adim7 use the same four keys.
Can I practise Cdim7 with a MIDI keyboard?
Yes. In ChordRunner a USB MIDI keyboard is detected automatically, and an acoustic piano works through the microphone. Cdim7 counts in any inversion, as long as C, Eb, Gb, Bbb sound together.
Your instrument is the controller.
ChordRunner is a browser game that teaches piano and guitar chords: a chord appears on screen, you play it on a real instrument, and your runner jumps. MIDI keyboard or microphone, both work.
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