Aaug is A, C# and E# — A with the fifth raised a semitone.
It sounds stretched, and suspended between keys. Its commonest job is passing between a major triad and its sixth or seventh, with the raised fifth as a single voice walking up.

| A | C# | E# |
|---|---|---|
| 1 | 3 | ♯5 |
Passing chord — it belongs to no key in particular.
Also written A+, A(#5) or A augmented. The same chord either way; which spelling you meet depends on who wrote the chart.
Aaug in root position puts A in the bass, which is the chord as it is spelled: the note it is named after underneath everything else.
8 of Aaug’s 9 common shapes do this: xxx221, x03221, 54322x, 5x7665, xx7665, x-12-11-10-10-x, x-12-x-14-14-13, x-12-15-14-14-x.
Start with xxx221 — only 3 fretted notes and down at the nut. 1 of the 9 shapes here sits in open position. None of them needs a barre. Together they cover the neck from the 1st fret to the 15th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| xxx221 | 1st fret | A, root position | E# | all fretted |
| x03221 | open position | A, root position | E# | 1 open string |
| 54322x | 2nd fret | A, root position | C# | all fretted |
| 5x7665 | 5th fret | A, root position | A | all fretted |
| xx7665 | 5th fret | A, root position | A | all fretted |
| x-x-11-10-10-9 | 9th fret | C#, 1st inversion | C# | all fretted |
| x-12-11-10-10-x | 10th fret | A, root position | A | all fretted |
| x-12-x-14-14-13 | 12th fret | A, root position | E# | all fretted |
| x-12-15-14-14-x | 12th fret | A, root position | C# | all fretted |
The same notes rebuilt from scratch give 45 triad voicings, each on its own page.
Every note of Aaug is in A whole tone and A altered.
Change one note of Aaug and you have A (the sharp fifth becomes a fifth), Amaj7#5 (add the major seventh), Aaug7 (add the flat seventh), A/E (the sharp fifth becomes a fifth), A/F (add the fifth) or A/C# (the sharp fifth becomes a fifth).
Aaug is a augmented chord — root, major third, sharp fifth. Augmented chords on every root.
On Aaug’s sound and use this page follows Stefan Kostka, Dorothy Payne & Byron Almén, Tonal Harmony (McGraw-Hill, 8th ed., 2018). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.