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C diminished 7th chord on guitar (Cdim7)
Also called or written Cdim7 or C°7
C diminished 7th contains C, E♭, G♭ and B♭♭. The 1st fret shape is a barre chord that requires a strong index finger.
How it is built
Formula 1, ♭3, ♭5, ♭♭7
- Root positionC–E♭–G♭–B♭♭Cdim7×-3-1-2-1-2
- First inversionE♭–G♭–B♭♭–CCdim7/E♭×-×-1-2-1-2
- Second inversionG♭–B♭♭–C–E♭Cdim7/G♭2-0-1-2-1-×
- Third inversionB♭♭–C–E♭–G♭Cdim7/B♭♭×-0-1-2-1-2
How do you play a C diminished 7th chord on guitar?
C diminished 7th is played at the 1st fret as × 3 1 2 1 2: barre your index finger across fret 1, pinky finger on the A string at fret 3, middle finger on the G string at fret 2 and ring finger on the high e string at fret 2. The low E string stays muted.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | muted | — | — |
| 5 (A) | 3 | 4 | C (1) |
| 4 (D) | 1 | 1 (barre) | E♭ (♭3) |
| 3 (G) | 2 | 2 | B♭♭ (6) |
| 2 (B) | 1 | 1 (barre) | C (1) |
| 1 (e) | 2 | 3 | G♭ (♭5) |
AdvancedThe 1st fret barre requires the index finger to fret the D and B strings cleanly while the pinky reaches the 3rd fret on the A string.
2nd fret
C diminished 7th is played at the 2nd fret as × 3 4 2 4 2: barre your index finger across fret 2, middle finger on the A string at fret 3, ring finger on the D string at fret 4 and pinky finger on the B string at fret 4. The low E string stays muted.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | muted | — | — |
| 5 (A) | 3 | 2 | C (1) |
| 4 (D) | 4 | 3 | G♭ (♭5) |
| 3 (G) | 2 | 1 (barre) | B♭♭ (6) |
| 2 (B) | 4 | 4 | E♭ (♭3) |
| 1 (e) | 2 | 1 (barre) | G♭ (♭5) |
7th fret
C diminished 7th is played at the 7th fret as 8 9 7 8 7 ×: barre your index finger across fret 7, middle finger on the low E string at fret 8, pinky finger on the A string at fret 9 and ring finger on the G string at fret 8. The high e string stays muted.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | 8 | 2 | C (1) |
| 5 (A) | 9 | 4 | G♭ (♭5) |
| 4 (D) | 7 | 1 (barre) | B♭♭ (6) |
| 3 (G) | 8 | 3 | E♭ (♭3) |
| 2 (B) | 7 | 1 (barre) | G♭ (♭5) |
| 1 (e) | muted | — | — |
8th fret
C diminished 7th is played at the 8th fret as 8 9 10 8 10 8: barre your index finger across fret 8, middle finger on the A string at fret 9, ring finger on the D string at fret 10 and pinky finger on the B string at fret 10.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | 8 | 1 (barre) | C (1) |
| 5 (A) | 9 | 2 | G♭ (♭5) |
| 4 (D) | 10 | 3 | C (1) |
| 3 (G) | 8 | 1 (barre) | E♭ (♭3) |
| 2 (B) | 10 | 4 | B♭♭ (6) |
| 1 (e) | 8 | 1 (barre) | C (1) |
10th fret
C diminished 7th is played at the 10th fret as × × 10 11 10 11: index finger on the D string at fret 10, ring finger on the G string at fret 11, middle finger on the B string at fret 10 and pinky finger on the high e string at fret 11. The low E and A strings stay muted.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | muted | — | — |
| 5 (A) | muted | — | — |
| 4 (D) | 10 | 1 | C (1) |
| 3 (G) | 11 | 3 | G♭ (♭5) |
| 2 (B) | 10 | 2 | B♭♭ (6) |
| 1 (e) | 11 | 4 | E♭ (♭3) |
Why it sounds like that
C diminished 7th is built from the intervals 1, ♭3, ♭5 and ♭♭7. The ♭♭7, a diminished seventh above the root, creates the chord's distinctive tension. Compare it with C minor 7th flat 5th, which has a minor seventh instead.
What goes wrong with C diminished 7th?
- Letting the low E string ring instead of muting it.
- Not pressing the barre hard enough, causing the B string to buzz.
- Flattening the middle finger onto the B string and muting the barre note.
When to use it
C diminished 7th often resolves to D minor or D major. It suits tense jazz and classical passages.
Changing to and from C diminished 7th
- Sliding the shape up one fret to the 2nd fret gives C♯ diminished 7th.
- From D minor, move the pinky from the 3rd fret of the A string to the 3rd fret of the D string and add the barre.
Which voicing to use
The 1st fret barre keeps the root C in the bass and is the default voicing. The 7th fret barre shape moves the root to the low E string for a heavier sound.
Other C chords
Common questions
How is C diminished 7th written?
C diminished 7th is written C°7 or Cdim7.
What is the difference between C diminished 7th and C minor 7th flat 5th?
C diminished 7th has a diminished seventh (B♭♭), while C minor 7th flat 5th has a minor seventh (B♭). The diminished seventh makes the chord fully diminished.
Why is the low E string muted in the 1st fret shape?
The open low E is not a chord tone of C diminished 7th. Muting it keeps the voicing clean and the bass note on C.