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A#dim(Diminished Chord)

Built from two stacked minor thirds. Creates maximum tension and instability.

Notes
A# – C# – E
Intervals (semitones)
0 – 3 – 6
Type
Triad

🎹 A#dim on Piano

Press highlighted keys simultaneously to play the A#dim chord.

R
A#(Root (R))
2
C#(Minor 3rd (♭3))
3
E(Tritone (♭5))

🎸 A#dim on Guitar

The A#dim chord uses notes A#, C#, E. Build a voicing by finding these notes on any strings — root on the 6th string is a common starting point for barre chord shapes.

Interval Analysis

DegreeInterval NameSemitonesNote in A#
RootRoot (R)0A#
3rdMinor 3rd (♭3)3C#
5thTritone (♭5)6E

About the A# Diminished Chord

The A#dim chord (A# Diminished) consists of 3 notes: A#, C#, E. Built from two stacked minor thirds. Creates maximum tension and instability.

To build any diminished chord, apply intervals of 0, 3, 6 semitones above the root. Starting from A#: the notes land on A#, C#, E.

Playing A#dim on Piano

Press A#, C#, E simultaneously. In root position, A# is lowest. First inversion places C# in the bass for a lighter sound; second inversion uses E as the bass note.

Common Chord Progressions Using A#dim

  • I–IV–V: A#dim – D#dim – Fdim (blues and rock)
  • I–V–vi–IV: A#dim – F – Gm – D# (pop staple)
  • I–vi–IV–V: A#dim – Gm – D# – F (50s progression)

The A#dim Chord in Context

As a diminished chord, A#dim is the tonic (I) in the key of A# major. It also appears as the IV chord in F major, and as the V chord in D# major — making it one of the most important chords across all of Western music.

Other A# Chords

A#
Major
A#m
Minor
A#7
Dominant 7th
A#maj7
Major 7th
A#m7
Minor 7th
A#aug
Augmented

Diminished Chord in All 12 Keys

CdimC#dimDdimD#dimEdimFdimF#dimGdimG#dimAdimA#dimBdim
🎹 Virtual Piano
Play A#dim on piano
🎸 Virtual Guitar
See on the fretboard
🎵 A# Scale
Notes that fit A#dim
🎶 Songs
Find songs using A#dim

FAQ

A#dim Chord — Frequently Asked Questions

What notes are in the A#dim chord?
The A# Diminished chord contains: A#, C#, E. These notes are derived by applying the diminished interval formula (0–3–6 semitones) to the root note A#.
What is the A#dim chord used for?
Built from two stacked minor thirds. Creates maximum tension and instability. The A#dim chord is used across pop, rock, jazz, and classical music. As the I chord in the key of A# major, it functions as the most stable resting point in progressions.
How do you play A#dim on piano?
On piano, play A#, C#, E simultaneously. In root position, A# is the lowest note. Inversions move the bass note up — first inversion has C# lowest, second inversion has E lowest.
How many notes are in a diminished chord?
A diminished chord has 3 notes: A#, C#, E (in A#). It is a triad — the most fundamental chord type.
What is the difference between A# major and A# minor?
The A# major chord (A#–D–F) uses a major third (4 semitones), giving it a bright, happy sound. The A# minor chord (A#–C#–F) uses a minor third (3 semitones), giving it a darker, emotional sound.
What key does A#dim belong to?
A#dim naturally serves as the I chord in the key of A# major. It also appears as IV in the key of F major, and as V in the key of D# major.
Can I play A#dim on ukulele?
Yes. The ukulele uses GCEA tuning with 4 strings. The A#dim chord notes (A#, C#, E) can be fretted on a ukulele, though the shapes differ from guitar due to the 4-string layout and shorter scale.
What chords go well with A#dim?
In the key of A# major, A#dim pairs naturally with D# major (IV), F major (V), and Gm (vi). The classic I–IV–V (A#dim–D#–F) is the foundation of blues, country, and rock.
What is a chord inversion of A#dim?
An inversion places a non-root note in the bass. A#dim root position: A# in bass. First inversion: C# in bass. Second inversion: E in bass. Inversions create smoother bass line movement without changing the harmony.
How do I memorize the notes in a diminished chord?
Remember the formula: 0–3–6 semitones from root. For A#dim: start on A#, add 3 semitones, then 6 semitones. Practicing this across all 12 roots builds instant recognition of any diminished chord.