A Flat Diminished Chord
The a flat diminished chord (A♭dim) is A♭, C♭, D. Play those 3 notes together and you have it.
It is the vii° chord of A Major and turns up in 1 other key.
The keyboards below are live. Press the notes and the page grades what you played, so you can check the shape without guessing, root position first, then both inversions, which is where chord playing stops sounding like exercises and starts sounding like music.
How to play A♭dim on piano
Play the A Flat Diminished Chord (Root Position)
Tap the highlighted keys — any order.
Right hand: fingers 1, 3 and 5 on A♭, C♭, D, thumb on the A♭.
Left hand: the same notes, fingers 5, 3 and 1, little finger on the A♭.
Press all the notes at once rather than rolling them, and listen for whether they arrive together. A chord that is nearly simultaneous is the single most common thing that makes playing sound robotic, and it is fixable in a week.
Try it on the keyboard above. Any octave counts.
A♭dim, first inversion
Play the A Flat Diminished Chord (First Inversion)
Tap the highlighted keys — any order.
C♭, D, A♭: A♭dim with the third, C♭, at the bottom. A chord chart writes it A♭dim/C♭. The outside fingers span a major 6th, C♭ up to A♭, so the right hand takes it with fingers 1, 2 and 5.
Use it when the chord before or after shares notes with it: the hand moves one or two keys instead of jumping, and the bass line steps rather than leaps. Play A♭dim/C♭ on the keyboard above, then A♭dim in root position, and listen to which way each one leans.
A♭dim, second inversion
Play the A Flat Diminished Chord (Second Inversion)
Tap the highlighted keys — any order.
D, A♭, C♭: A♭dim with the fifth, D, at the bottom. A chord chart writes it A♭dim/D. The outside fingers span a major 6th, D up to C♭, so the right hand takes it with fingers 1, 3 and 5.
Use it when the chord before or after shares notes with it: the hand moves one or two keys instead of jumping, and the bass line steps rather than leaps. Play A♭dim/D on the keyboard above, then A♭dim in root position, and listen to which way each one leans.
How the A♭dim chord is built
Count in semitones from the root, A♭:
| Note | Semitones above the root | Interval |
|---|---|---|
| A♭ | 0 | root |
| C♭ | 3 | minor 3rd |
| D | 6 | diminished 5th |
That pattern is the chord. Move the whole shape up two semitones and you have the same chord on a different root, which is why learning one quality well is worth more than memorizing twelve chords separately.
A semitone is the distance to the very next key, whether black or white. Count them on the keyboard above if the numbers do not mean much yet; they will after a few chords.
Where A♭dim turns up
A♭dim is a chord of 2 keys. Knowing which is how you work out what to play next.
| Key | Role |
|---|---|
| A Major | vii° |
| F Sharp Minor | ii° |
If a piece is in A Major and this chord appears, it is doing the job of the vii°. The other keys give you the same chord with a different meaning, and that is the whole reason a song can pivot from one key to another on a single chord.
Practicing A♭dim
Five minutes, in this order:
- Right hand, root position. A♭, C♭, D, played together, four times.
- Both inversions, in order, going up and then back down. Say which one you are on.
- Left hand alone, the same three steps. It is always the weaker hand and always the one people skip.
- Hands together, left hand playing just the root while the right hand plays the chord.
- Find it in a piece. A chord you have only met in isolation does not stay learned.
Do not chase speed here. A chord you can place accurately without looking is worth more than four you can nearly place quickly.