Chord · A Diminished
Adim Chord
Adim is A, C and Eb — tense, unstable; resolves outward.
Adim on every instrument
The same 3 notes, 6 sets of hands. Open a diagram for alternate shapes, audio and the mistakes to avoid.
What Adim is made of
Adim (A diminished) is built from the notes A, C, Eb, with the interval pattern 1, b3, b5.
Stack 1, b3 and b5 on a root of A and you get A, C and Eb. That interval recipe is what makes the chord a diminished chord — move the same shape to another root and the character travels with it, which is why Cdim sounds like a transposed Adim.
Diminished: Tense, unstable; resolves outward.
Spelling: the notes above are written the way a score would write them, not simplified to the nearest piano key. That is why this chord is spelled with E♭ rather than its enharmonic equivalent.
Keys that contain Adim
All 3 notes sit inside the scale of 2 keys. The roman numeral marks the degree the chord is rooted on.
Major keys
Minor keys
Other chords on A
Same root, different colour.
The same diminished shape, moved
The identical interval recipe, built on other roots.
Questions people ask about Adim
- What notes are in the Adim chord?
- Adim is made of A, C and Eb — the 1, b3 and b5 degrees of a diminished chord built on A.
- What keys use the Adim chord?
- Every note of Adim belongs to 2 keys: Bb Major (vii°), G Minor (ii°). The roman numeral is the scale degree the chord is rooted on.
- How do you play Adim on guitar and piano?
- This page shows Adim on guitar, piano, ukulele, bass, mandolin and banjo — 9 voicings in total. Each diagram links to the full instrument page with alternate shapes, audio and common mistakes.
Learn the theory behind it
Why Adim behaves the way it does — the guides that explain the chord instead of just spelling it.