A#dim7

Q: What notes are in the A#dim7 chord?

The A#dim7 chord (A# Diminished 7th) contains: A#, C#, E, G. Its interval structure is shown above in the Theory section.

Q: How do I build A#dim7 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#dim7 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#dim7?

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 7th

Octaves

Musical context

ChordA#dimTriad

ChordA#dim7A# Diminished 7th

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 7th
Symbol: A#dim7
Root: A#
Quality: Diminished 7th

Chord notes

1A#root

b3C#minor 3rd

b5Edim 5th

bb7Gdim 7th

Functions & resolutions

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
b6F#
bb7G
resolves down to the tonic 5th
Main resolution: A#dim7source
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#dim7source
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#dim7source
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#dim7source
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#dim7source
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: Fully diminished, symmetric and unstable
Characteristic interval: Diminished 7th (°7)
Description: Four tones are stacked in minor 3rds; the diminished 5th and 7th create two tritones. Symmetry allows any tone to be enharmonically reinterpreted as the root.
Application: Leading-tone seventh in minor
Secondary leading-tone chords
Chromatic voice leading

Voicing & structure

Root position

v1A#(A#4)Bass

root

v2C#(C#5)m3from A#

v3E(E5)m3from C#

v4G(G5)m3from E

Harmony

Compatible scales

All chord tones are contained in these scales — use them for improvisation.

ScaleC# Romanian minor ScaleC# Ukrainian Dorian ScaleE Romanian minor ScaleE Ukrainian Dorian ScaleG Romanian minor ScaleG Ukrainian Dorian ScaleA# Romanian minor ScaleA# Ukrainian Dorian ScaleC Phrygian dominant ScaleD Harmonic minor

This chord on guitar 🎸

See how A#dim7 looks on guitar.

Explore

Circle of fifths

Highlighted major keys contain this chord among their diatonic harmonies.

Relative key: GmG minor
Dominant: FF major
Subdominant: EbEb major
Key signature: 2 flats (Bb, Eb)

What to learn next

ScaleBb Chromatic scaleScale to improvise over this chord ChordA# DiminishedA nearby chord on the same root — compare the sound PracticeChord trainerLock the fingering into muscle memory ProgressionChord progressionsHow this chord works inside real progressions ChordA# Half-dim 7Another related chord to practise

Recommended for you

A# DiminishedA chord that sounds close

A# Half-dim 7A chord that sounds close

Bb Chromatic scaleA scale related to this chord

Bb Diminished scaleA scale related to this chord

Practice

Keyboard Trainer

Reinforce it in practice — play and name notes on the interactive keyboard.

Open Trainer

Test yourself

(Press any key to start)

What notes are in the A#dim7 chord?

How do I build A#dim7 on the keyboard?

Which keys is A#dim7 found in?

What can I substitute for A#dim7?