C♯dim7
C# Diminished 7th — perfectly symmetrical stacked minor thirds — the ultimate passing chord, able to resolve almost anywhere.
The keys
C♯ – E – G – B♭
What's inside C♯dim7
| Note | Interval from root | Degree |
|---|---|---|
| C♯ | Root | 1 |
| E | Minor 3rd | b3 |
| G | Diminished 5th | b5 |
| B♭ | Diminished 7th | bb7 |
Inversions
| Position | Keys (low → high) |
|---|---|
| Root position | D♭4 – E4 – G4 – B♭4 |
| 1st inversion | E4 – G4 – B♭4 – D♭5 |
| 2nd inversion | G4 – B♭4 – D♭5 – E5 |
| 3rd inversion | B♭4 – D♭5 – E5 – G5 |
A working voicing
Split the chord between two hands the way working players do — a solid shell low down, the colour tones up top:
| Hand | Keys |
|---|---|
| Left (shell) | D♭2 – B♭2 |
| Right (colour) | E4 – G4 |
Where C♯dim7 lives
As the ii chord
C♯dim7 → G♭7 → Bmaj7
Minor-family sevenths live on the ii — this is the move they were born for.
Stepwise colour
D♭ → C♯dim7 → E♭m7
Used as a passing colour between neighbouring chords.
Put C♯dim7 under your fingers
Hear every voicing, see the keys light up, and drill it in the interactive Chord & Voicing Lab.
Open the Chord & Voicing Lab →