A° (Diminished)

A · C · Eb · 3 notes

Chord

Formula: R – ♭3 – ♭5

A R

C ♭3

Eb ♭5

Bass note: A

Key	Degree
Bb Major	vii°
G Minor	ii°

The A° chord is a diminished chord built on A. It consists of the notes A, C, Eb (scale degrees R, ♭3, ♭5).

Diminished chords stack two minor 3rds (3+3 semitones), creating a tense, unresolved sound. They typically appear as the vii° in major keys.

Use the Key Finder to find what key these notes belong to, or the Progression Builder to use this chord in a sequence.