Adim chord on guitar
Adim (A diminished) is a diminished chord built on A. It has 3 notes, A, C and E♭, and its formula is 1 ♭3 ♭5.
Notes and intervals of Adim
From the root upwards, Adim contains root (A), minor 3rd (C) and diminished 5th (E♭). Those intervals give the chord its colour: the formula 1 ♭3 ♭5 works the same way in every key, so once you know it for A you can build the chord on any note.
| Degree | Interval | Note |
|---|---|---|
| 1 | root | A |
| ♭3 | minor 3rd | C |
| ♭5 | diminished 5th | E♭ |
How to play Adim on guitar
The first shape above reads x 0 1 2 1 x from the low E string to the high E string (x means you do not play that string, 0 is an open string). The lowest note you play is A. The other diagrams show the same chord higher up the neck: pick the one closest to the chords before and after it in your song.
Let the open strings ring: strum slowly once and check that every note sounds clean before you speed up.
Which keys use Adim?
You find Adim as a diatonic chord in B flat major (vii°). The most common case is B flat major, where it plays the role of vii°.
Scales to play over Adim
To improvise over Adim, start with A blues scale. All of these scales contain every note of the chord: A blues scale and A Locrian mode. Aim for the chord notes on strong beats and use the other notes to move between them.
About diminished chords
Two stacked minor thirds: 1 ♭3 ♭5. The diminished fifth (a tritone) makes the diminished chord the most unstable triad: tense, dark and restless. It rarely stands alone and pulls towards the chord a semitone above its root. For example Bdim: B D F. Add a diminished seventh and you get the symmetrical diminished seventh chord.
In a major key it sits on vii° (for example Bdim in C major), acting as a lighter V7 that resolves to I. In a minor key it sits on ii°. Passing diminished chords connect neighbouring chords chromatically, for example I ♯i° ii (C C♯dim Dm). Classical music, jazz, ragtime and film scores use it to build suspense.
The triad is usually played as a small three or four-string shape on the middle or top strings, since full barres are awkward. Many guitarists play dim7 instead: a movable four-string shape that repeats every 3 frets, because the chord divides the octave into equal minor thirds. Slide it up three frets to hear a new inversion.
dim (three notes) and dim7 (four notes, with a diminished seventh) are not the same, though 'dim' on a jazz chart often means dim7. And dim is not m7♭5: the half-diminished chord adds a minor seventh (for example Bm7♭5: B D F A) and sounds much softer. Symbols: ° means diminished, ø means half-diminished.
Frequently asked questions
What notes are in the Adim chord?
Adim (A diminished) contains A, C and E♭. In intervals: root (A), minor 3rd (C) and diminished 5th (E♭).
How do you play Adim on guitar?
The easiest shape is x 0 1 2 1 x, from the low E string to the high E string. This page shows 3 positions with finger numbers.
What scale goes with Adim?
A blues scale fits Adim best. Other scales that contain all its notes: A Locrian mode.
What key is Adim in?
Adim belongs to B flat major (vii°). In B flat major it is the vii° chord.
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