Also written Adim or A°
A diminished contains A, C, and E♭. The 5th-fret shape spreads one finger per string across four frets, so keep the wrist low and the fingers arched.
The same three notes, with a different one in the bass.
A diminished is built from the formula 1, ♭3, ♭5. The ♭5 interval gives the chord its tense, unstable quality. Compare A minor, which raises the fifth to E.
A diminished works as a passing chord between A minor and B♭ major, or over a G natural minor line. The ♭5 interval creates a tritone that pulls toward the next chord, suiting jazz walk-ups and metal riffs.
The 5th-fret shape puts A in the bass for a root-position sound. The Adim/C inversion at the 8th fret places C in the bass, which softens the chord's bite.
A diminished is played at the 5th fret as 5 6 7 5: index finger on the E string at fret 5, ring finger on the A string at fret 6, pinky finger on the D string at fret 7 and middle finger on the G string at fret 5.
Tip — The pinky must reach the 7th fret on the 2nd string while the middle finger holds the 5th fret on the 1st string.
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 5 | 1 | A (1) |
| 3 (A) | 6 | 3 | E♭ (♭5) |
| 2 (D) | 7 | 4 | A (1) |
| 1 (G) | 5 | 2 | C (♭3) |
A diminished is played at the 6th fret as 8 6 7 8: ring finger on the E string at fret 8, index finger on the A string at fret 6, middle finger on the D string at fret 7 and pinky finger on the G string at fret 8.
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 8 | 3 | C (♭3) |
| 3 (A) | 6 | 1 | E♭ (♭5) |
| 2 (D) | 7 | 2 | A (1) |
| 1 (G) | 8 | 4 | E♭ (♭5) |
A diminished is played at the 5th fret as × 6 7 5: middle finger on the A string at fret 6, ring finger on the D string at fret 7 and index finger on the G string at fret 5. The E string stays muted.
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | muted | — | — |
| 3 (A) | 6 | 2 | E♭ (♭5) |
| 2 (D) | 7 | 3 | A (1) |
| 1 (G) | 5 | 1 | C (♭3) |
A diminished is played at the 10th fret as 11 12 10 ×: middle finger on the E string at fret 11, ring finger on the A string at fret 12 and index finger on the D string at fret 10. The G string stays muted.
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 11 | 2 | E♭ (♭5) |
| 3 (A) | 12 | 3 | A (1) |
| 2 (D) | 10 | 1 | C (♭3) |
| 1 (G) | muted | — | — |
Write A° or Adim. The root is A, and the chord is spelled A–C–E♭.
The ♭5 interval creates a tritone with the root, which wants to resolve. This tension is what gives diminished chords their forward drive.
Only when you want that darker, more dissonant color. A diminished lowers the fifth, so it clashes with melodies that expect the perfect fifth E.