A augmented chord (Aaug)

The A augmented chord (Aaug) is an augmented triad: A, C♯ and E♯, two major thirds stacked on top of each other (root, major third and augmented fifth).

Because it splits the octave into three equal major thirds, A augmented has the same notes as D♭ augmented and F augmented; only the bass note changes.

With A, C♯ and E♯, A augmented does not fit any major or natural minor scale: it is the chord on the third degree (III+) of the harmonic minor scale and is mostly used as a passing chord, as in I–I+–IV.

Below: voicings, notes on the fretboard, ukulele, piano and inversions.

How to play A augmented on guitar

There are 3 guitar voicings.

Frets from the 6th string to the 1st: x = not played, 0 = open string.

  • Voicing 1: x-0-3-2-2-1, open position, with A in the bass (fingers x-0-4-2-3-1).
  • Voicing 2: 5-x-7-6-6-x, with A in the bass (fingers 1-x-4-2-3-x).
  • Voicing 3: x-12-11-10-10-x, with A in the bass (fingers x-4-3-1-2-x).

Notes of the A augmented chord on the fretboard

A augmented has 3 notes: A, C♯ and E♯. This is where they fall on each string, from the nut to the 12th fret (fret number in parentheses):

  • String 6 (E): E♯ (1) · A (5) · C♯ (9)
  • String 5 (A): A (0) · C♯ (4) · E♯ (8) · A (12)
  • String 4 (D): E♯ (3) · A (7) · C♯ (11)
  • String 3 (G): A (2) · C♯ (6) · E♯ (10)
  • String 2 (B): C♯ (2) · E♯ (6) · A (10)
  • String 1 (E): E♯ (1) · A (5) · C♯ (9)

Formula and intervals of A augmented

Its formula is 1-3-♯5; in semitones from the root, 0-4-8.

  • A: Root, the note that gives the chord its name
  • C♯: Major third (M3), 4 semitones above A
  • E♯: Augmented fifth (A5), 8 semitones above A

A augmented on ukulele

  • Ukulele (G C E A): 2-1-1-0, barre at fret 1; it sounds A, C♯, E♯ and A.

A augmented on piano

  • Keys: A4, C♯5 and E♯5.

Inversions of A augmented

Each inversion puts a different note in the bass.

  • Root position: A, C♯ and E♯, with A in the bass.
  • First inversion (Aaug/C♯): C♯, E♯ and A, with C♯ in the bass.
  • Second inversion (Aaug/E♯): E♯, A and C♯, with E♯ in the bass.

Keys that use A augmented

A augmented (A, C♯ and E♯) is not a diatonic chord of any major or natural minor key. The augmented fifth does appear in the harmonic and melodic minor scales, where A augmented is the chord on the third degree.

Progressions with A augmented

  • Augmented passing chord in A major (I–I+–IV): A – Aaug – D

Frequently asked questions

What notes are in the A augmented chord?

A, C♯ and E♯: root, major third and augmented fifth. Its formula is 1-3-♯5.

Why does A augmented sound the same as D♭ augmented and F augmented?

Because the augmented chord divides the octave into three major thirds: A, C♯ and E♯. When you invert it, the bass note changes but the notes stay the same distance apart, so A augmented uses the same keys and frets as D♭ augmented and F augmented.

What is the A augmented chord used for?

Mostly as a passing chord, as in I–I+–IV: on the same root, the fifth of the major triad rises a half step, giving A, C♯ and E♯, which pushes toward IV. It is also the III+ of the harmonic minor scale.