C#dim7 guitar chord
An open string left ringing against a fretted grip. Because it costs no finger, it sounds a note the closed shape has none left for -- a tension on top, or a pedal root underneath. Either a familiar grip with open strings added, or a shape so sparse the open strings carry the chord. These belong to their key rather than to a shape, so D, A, G and E have many and Eb a handful.
- Tap a note to hear it
- Arrows change position
- Fingers, notes or intervals
- Play the chord
About C#dim7 — open string voicings
C#dim7 is C#, E, G and Bb — C#dim with a diminished seventh stacked on top.
It sounds suspenseful and rootless. Three stacked minor thirds divide the octave evenly, so the same four notes spell four dim7 chords and the shape repeats every three frets.
C#dim7 notes and formula
| C# | E | G | Bb |
|---|---|---|---|
| 1 | ♭3 | ♭5 | ♭♭7 |
Leading-tone or passing chord — it can resolve almost anywhere.
Also written C#°7, C#o7 or C# diminished 7. The same chord either way; which spelling you meet depends on who wrote the chart.
How to play C#dim7
An open string left ringing against a fretted grip. It costs no finger, so it can sound a note the closed shape has none left for: a tension on top, or a pedal root underneath.
These belong to their key rather than to a shape: they cannot be moved up the neck. D, A, G and E have many; E♭ has a handful.
C#dim7 has 1 of them, only on strings 6-5-4-3-2-1, all of them at the 5th fret — all in one inversion, so the bass note never moves. The one to learn first is the E shape at the 5th fret, which is the easiest grip here.
Start with xx2323 — no barre and down at the nut. None of the shapes for C#dim7 uses an open string, so every one of them is movable; the lowest sits at the 2nd fret. 2 of the 6 need a barre. Together they cover the neck from the 2nd fret to the 12th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| xx2323 | 2nd fret | E, 1st inversion | G | all fretted |
| x45353 | 3rd fret | C#, root position | G | all fretted |
| xx5656 | 5th fret | G, 2nd inversion | Bb | all fretted |
| 9x8989 | 8th fret | C#, root position | C# | barred |
| 9-10-11-9-11-9 | 9th fret | C#, root position | C# | barred |
| x-x-11-12-11-12 | 11th fret | C#, root position | E | all fretted |
The same notes rebuilt from scratch give 5 shell, 14 drop 2 and 10 drop 3 voicings, each on its own page.
Tensions. A shell of C#dim7, root, third and seventh, leaves a string free, and the tones that belong over it are the 9 (D#), the 11 (F#), the b13 (A) and the maj7 (B#).
How to use C#dim7
A diminished seventh divides the octave evenly, so C#dim7 has no single root and no single destination: it can lead to F# or to D, and it is the same four notes either way.
What to play over C#dim7
Every note of C#dim7 is in C# diminished and C# half-whole diminished.
Chords near C#dim7
Change one note of C#dim7 and you have C#dim (drop the sixth), C#m6 (the flat fifth becomes a fifth), C#m7b5 (the sixth becomes a flat seventh) or C#mMaj7b5 (the sixth becomes a major seventh).
C#dim7 is a diminished chord — root, minor third, flat fifth. Diminished and half-diminished chords on every root.
On C#dim7’s sound and use this page follows Stefan Kostka, Dorothy Payne & Byron Almén, Tonal Harmony (McGraw-Hill, 8th ed., 2018). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.