A♯ Diminished
Also Known As
Hear the A♯ Diminished chord played for you.
A♯°
A♯ – C♯ – E
Formula:R-m3-d5
Intervals:P1-m3-d5
Scale Degrees:1-b3-b5
Introduction
The A♯ Diminished chord is a three-note chord made up of A♯, C♯, and E. It is built from a root, minor third, and diminished fifth.
The A# Diminished piano chord (A#dim) consists of the notes A#, C#, E. It is built by stacking two minor thirds (3 semitones each), giving it a tense, unstable, and dissonant character. Formula: R-m3-d5 | Scale degrees: 1-b3-b5.
Notes
A♯ Diminished Inversions
| Position | Notes |
|---|---|
| Root Position | A♯ – C♯ – E |
| 1st Inversion | C♯ – E – A♯ |
| 2nd Inversion | E – A♯ – C♯ |
Key Signature
The key of A# Diminished (enharmonically equivalent to Bb Diminished) has 2 flats.
B♭E♭
Order of flats
Flats are added in a fixed order — the reverse of the sharp order. Each new flat key adds the next flat on the list.
B♭E♭A♭D♭G♭C♭F♭
Mnemonic: Battle Ends And Down Goes Charles’ Father
Chords in the Key of A♯ Major
These are the diatonic triads built on each degree of the A♯ major scale:
C
D
E
F
G
A
B
C
D
E
F
G
A
B
I — A♯ Major (major)
Theory: Intervals
Formula: R-m3-d5
Intervals: P1-m3-d5
The A♯ Diminished is built by stacking intervals from the root note. The formula R-m3-d5 describes the scale degrees used. The intervals P1-m3-d5 show the distance between each note in the chord.
A♯ Diminished — Frequently Asked Questions
What notes are in the A# Diminished chord?
The A# Diminished chord contains: A# (root), C# (minor third), and E (diminished fifth). Both intervals are compressed: the minor third is 3 semitones above the root, and the diminished fifth is 6 semitones — a tritone.
How does A# Diminished differ from A# Minor?
A# Minor has a perfect fifth. A# Diminished lowers the fifth by one semitone to E (diminished fifth). That extra compression creates intense harmonic tension — the tritone between root and diminished fifth is the most dissonant interval in Western music.
What is the symbol for the A# Diminished?
A# Diminished is written as A#dim or A#°. The ° or "dim" symbol means both the third and fifth are minor/diminished. Do not confuse with A#dim7 or A#ø (half-diminished), which include additional notes.
What are the inversions of A# Diminished?
First inversion (A# Diminished/C#): C#–E–A#. Second inversion (A# Diminished/E): E–A#–C#. Diminished triads are used in classical music as the vii° chord — the chord one semitone below the tonic, with strong resolution pull.
How is A# Diminished used in music?
A# Diminished most commonly functions as the vii° chord in a major key, creating strong resolution back to the tonic. It also works as a chromatic passing chord between two nearby chords, and in classical music as a brief point of dissonance. Jazz uses the full four-note dim7 more often than the triad.
What songs use diminished chords?
Michelle (Beatles) uses a diminished chord as a chromatic passing chord. Many classical pieces use vii°–I cadences. Jazz standards use dim7 chords as chromatic passing and approach chords. Diminished harmony also appears in flamenco and film music for dramatic tension.
Practice Tips
- Compare A# Minor and A# Diminished: only the fifth changes (E vs perfect fifth). Play both back to back — the extra compression is striking.
- The tritone between A# and E creates maximum tension — practice just this two-note interval to hear its characteristic sound.
- A# Diminished most naturally resolves up by half step: play A#dim then a chord whose root is A# raised by one semitone.
- Practice all inversions: A#–C#–E, C#–E–A#, E–A#–C#.
- Use A# Diminished as a vii° chord: it is one semitone below A## Major — try A#dim → A## Major to feel this powerful classical resolution.
- In a major key, find where A# Diminished fits naturally as a passing chord between two diatonic chords a step apart.
Related Tools
Chord FinderLook up any chord — see the notes, hear it, and play along.Chord DrillTimed drills to build speed and recognition across all chord types.Practice RoomPlug in a MIDI keyboard and get real-time feedback on every chord and scale.Circle of FifthsVisualize key relationships, relative minors, and key signatures.MIDI MonitorLive MIDI message stream with note names, velocity, and a scrolling staff.