A diminished chord (Adim)
Adim is A, C and E♭: 1–♭3–♭5 built on A. Below: guitar, piano and ukulele, each playable.
On guitar
x-0-1-2-1-x · open · easy
- Notes
- A · C · E♭
- Formula
- 1 · ♭3 · ♭5
- First shape
- x-0-1-2-1-x
Adim on guitar: every shape, finger by finger
On piano
root position · A–C–E♭ · right hand 1-3-5
- Notes
- A · C · E♭
- Formula
- 1 · ♭3 · ♭5
Adim on piano: fingering and inversions
On ukulele
5-3-5-3 · movable · medium
- Notes
- A · C · E♭
- Formula
- 1 · ♭3 · ♭5
- First shape
- 5-3-5-3
Adim and the chords around it
The moves below are the ones you'll meet most, shown for guitar and piano.
- Adim → B♭ (leads up a half step)
Guitar: Adim (x-0-1-2-1-x) to B♭ (x-1-3-3-3-1): the index finger lays across the A to high E strings at the 1st fret, move the middle finger to the D string, 3rd fret, your ring finger lands on the G string, 3rd fret, the pinky finger comes down on the B string, 3rd fret. Everything moves: lift the whole hand and place the new shape in one go.
Piano: Adim to B♭: play B♭ in root position (B♭–D–F), while A moves up to B♭, C up to D and E♭ up to F. B♭ - Adim → B♭m (leads up a half step)
Guitar: Adim (x-0-1-2-1-x) to B♭m (x-1-3-3-2-1): the index finger lays across the A to high E strings at the 1st fret, your middle finger lands on the B string, 2nd fret, the ring finger goes to the D string, 3rd fret, the pinky finger comes down on the G string, 3rd fret. Nothing carries over, so drill it slowly, lifting and landing all fingers at once.
Piano: Adim to B♭m: play B♭m in root position (B♭–D♭–F), while A moves up to B♭, C up to D♭ and E♭ up to F. B♭m - Adim → Dm (iii in B♭ major)
Guitar: Adim (x-0-1-2-1-x) to Dm (x-x-0-2-3-1): your index finger lands on the high E string, 1st fret, your middle finger lands on the G string, 2nd fret, the ring finger goes to the B string, 3rd fret. No finger can stay, so practice lifting all of them together and landing the new shape as a unit. The two chords share A, which is why the change sounds smooth.
Piano: Adim to Dm: play Dm in 2nd inversion (A–D–F) and A stays under the same finger, while C moves up to D and E♭ up to F. Dm
How Adim is built
Adim is a diminished triad: two minor thirds stacked. It sounds tense and unstable and rarely stays long. Its most common job is to lead up a half step, so Adim usually moves to B♭ or B♭m.
Count keys (black and white) from A: 3 half steps up to C then 3 half steps up to E♭.
| Note | Role | Half steps | Hear it |
|---|---|---|---|
| A | root | 0 | |
| C | minor third | 3 | |
| E♭ | diminished fifth | 6 |
Keys and progressions with Adim
You'll find Adim as vii° in B♭ major. On the minor side it's ii° in G minor.
Chords close to Adim
- Adim and Am differ by one note: E♭ in Adim, E in Am. They share A and C. Am
Chords that share most of their notes with Adim: Cm6, Cdim7, D♯dim7, F7, F♯dim7, Adim7.
Every A chord
A diminished chord: questions
What notes are in the A diminished chord?
A, C and E♭. Adim is built 1–♭3–♭5 from A: C is the minor third and E♭ is the diminished fifth.
How do you play Adim on guitar?
The usual shape is x-0-1-2-1-x (open). All 4 guitar shapes.
How do you play Adim on piano?
Play A, C and E♭ with right-hand fingers 1-3-5. A sits between the last two black keys of the three. Inversions and left hand.
How do you play Adim on ukulele?
5-3-5-3 in standard GCEA tuning. More ukulele shapes.
What key is Adim in?
You'll find Adim as vii° in B♭ major. On the minor side it's ii° in G minor.
What's the difference between Adim and Am?
Adim and Am differ by one note: E♭ in Adim, E in Am. They share A and C.
Diagrams and sound come from the same data, tested so they match. Updated September 2026.