A#dim

Q: What notes are in the A#dim chord?

The A#dim chord (A# Diminished) contains: A#, C#, E. Its interval structure is shown above in the Theory section.

Q: How do I build A#dim on the keyboard?

Take the root and add the remaining chord tones following the interval formula. The highlight shows chord content, while the inversion control changes which chord tone is in the bass.

Q: Which keys is A#dim found in?

The chord acts as a diatonic degree in several keys — they are marked on the circle of fifths in the "Harmonic context" block.

Q: What can I substitute for A#dim?

A substitution depends on harmonic function and voice leading, not only on shared tones. Computed options appear in the "Substitutions" block and should be checked in context.

A# Diminished

Octaves

Musical context

ChordA#dimA# Diminished

ArpeggioA# minorBroken triad

ScaleA# minor7 notes

KeyA# minorMinor key

ProgressionAndalusianSequence

How the chord relates to the scale, mode, key and progression.

Theory

General info

Full name: A# Diminished
Symbol: A#dim
Root: A#
Quality: Diminished

Chord notes

1A#root

b3C#minor 3rd

b5Edim 5th

Functions & resolutions

Typical function in key: vii°Leading tone (vii°)B major
Stability / tension: Maximum tension — extremely unstable
Most common resolutions: BB Major DD Major
Unstable degrees: 2C
b3C#
resolves down to the 2nd
4D#
b5E
resolves inward to the 4th
Main resolution: A#dimsource
BB Major
Diminished A#dim acts as a leading-tone chord — resolves up a half step to B. All tones are unstable, moving by semitones inward and outward to stable degrees.
Other resolutions: A#dimsource
Deceptive resolution
DD Major
Due to its symmetry, a diminished 7th chord can resolve to any major or minor chord a minor 3rd apart.
A#dimsource
Modal resolution
CmC Minor
In modal context, a diminished chord can be used as a passing chord, connecting two diatonic chords through chromatic bass motion.
A#dimsource
Jazz reharmonization
A7A Dominant 7
In jazz, dim7 is often reinterpreted as a rootless dominant 7b9. For example, A#dim7 ≈ A7b9, opening additional resolution paths.
A#dimsource
Functional resolution
FmF Minor
A diminished chord can function as a leading-tone chord to any degree — not just the tonic. Often used before the ii, iii, or vi degrees.

Features

Character: Diminished, unstable
Characteristic interval: Diminished 5th (b5)
Description: Two stacked minor 3rds form a diminished 5th. The tritone makes the triad dissonant and directs voices toward neighbouring stable tones.
Application: vii° — vii degree of major
Passing chords
Horror, suspense