Cdim7 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 Cdim7 — open string voicings
Cdim7 is C, Eb, Gb and A — Cdim 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.
Leading-tone or passing chord — it can resolve almost anywhere.
Cdim7 notes and formula
| C | Eb | Gb | A |
|---|---|---|---|
| 1 | ♭3 | ♭5 | ♭♭7 |
Also written C°7, Co7 or C diminished 7. The same chord either way; which spelling you meet depends on who wrote the chart.
How to play Cdim7
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.
Cdim7 has 1 of them, only on strings 6-5-4-3-2, all of them at the 4th fret — all in one inversion, so the bass note never moves. The one to learn first is the Bbb shape at the 4th fret, which is the easiest grip here.
Play Cdim7 as a shell — root, third and seventh — and the spare string takes the 9 (D), the 11 (F), the b13 (Ab) or the maj7 (B).
All 7 common shapes as fret numbers, lowest string first. Hover or tap one to see it drawn.
- xx1212, 1st fret, Eb, 1st inversion, top note Gb, all fretted
- x34242, 2nd fret, C, root position, top note Gb, all fretted
- xx4545, 4th fret, Gb, 2nd inversion, top note A, all fretted
- 8x7878, 7th fret, C, root position, top note C, barred
- 8-9-10-8-10-8, 8th fret, C, root position, top note C, barred
- x-x-10-11-10-11, 10th fret, C, root position, top note Eb, all fretted
- x-x-13-14-13-14, 13th fret, Eb, 1st inversion, top note Gb, all fretted
How to use Cdim7
A diminished seventh divides the octave evenly, so Cdim7 has no single root and no single destination: it can lead to F or to Db, and it is the same four notes either way.
What to play over Cdim7
Every note of Cdim7 is in C diminished and C half-whole diminished.
Chords near Cdim7
Change one note of Cdim7 and you have Cdim (drop the diminished seventh), Cm6 (the flat fifth becomes the fifth), Cm7b5 (the diminished seventh becomes the flat seventh) or CmMaj7b5 (the diminished seventh becomes the major seventh).
Cdim7 is a diminished chord — root, minor third, flat fifth. Diminished and half-diminished chords on every root.
The common shapes and the derived voicings come from different places, and both are explained in how this site is built.