Root position
A# – C## – E##The root A# is the lowest note. This is the shape most people learn first.
3 notes · 1 · 3 · ♯5
A# Augmented Piano Chord (A#aug)
A#aug is built from A#, C## and E## — the formula 1 · 3 · ♯5, or 4 and 8 semitones above A#. The shape uses 1 white and 2 black keys, and you can hear it, invert it and compare it below.
Chord
A# Augmented
Notes
A# · D · F#Formula
1 · 3 · ♯5Right hand
1 · 3 · 5C
D
E
F
G
A
B
C
C#
D#
F#
G#
A#
Choose a chord, then play it. Finger numbers run from thumb (1) to little finger (5).
The finder above already holds A#aug. Press P or the Play chord button to hear A#, C##, E## sounded together, then change the root or the chord type to compare it with something else.
Chord tones
The notes in A#aug
An augmented triad is two major thirds stacked, so the fifth is raised by a semitone. Every note sits four semitones from the next, which leaves the chord without an obvious home and gives it a suspended, slightly uneasy colour. It is not diatonic to the major scale; it appears on the third degree of the harmonic minor scale and as an altered dominant.
| Note | Interval | Degree | Semitones | Right hand |
|---|---|---|---|---|
| A#black key | Root | 1 | 0 | 1 · thumb |
| C##white key | Major third | 3 | 4 | 3 · middle finger |
| E##black key | Augmented fifth | ♯5 | 8 | 5 · little finger |
Step by step
How to play A#aug on piano
- Find A#: it is the third black key in a group of three.
- Build upwards from A# using 4 and 8 semitones to reach C## and E##.
- With the right hand, place finger 1 on A#, finger 3 on C## and finger 5 on E##. Keep the wrist level and the knuckles rounded.
- Move your hand a little further in towards the fallboard so the black keys sit comfortably under your fingers.
- Play the notes together, then one at a time from the bottom up, and listen to how A#aug settles.
- Try first inversion as well: C## – E## – A#. Inversions let you change chords without jumping around the keyboard.
Inversions
A#aug in 3 positions
An inversion keeps the same 3 notes and simply moves the lowest one up an octave. Learning them means you can change chords with small hand movements instead of jumping to a new part of the keyboard.
First inversion
C## – E## – A#C## is the lowest note, so the major third sits in the bass and the notes below it move up an octave.
Second inversion
E## – A# – C##E## is the lowest note, so the augmented fifth sits in the bass and the notes below it move up an octave.
In context
Which keys contain A#aug
In G harmonic minor the chord functions as III+. It is the only key listed here that produces this chord from its own scale, which is part of why the chord sounds unusual.
- G harmonic minorIII+
Chord tones are spelled by the degree they occupy, so the third of a minor chord is written as a flat rather than a sharp even though it is the same key on the piano. A double sharp such as F## means the key one whole tone above F.
Compare
A#aug against A# major
A#aug and A# major share A# and C##. Moving the perfect fifth E# up 1 semitone to the augmented fifth E## turns A# major into A#aug.
Practise the pair together: hold the shared notes A#, C## still and move only the one finger. Hearing that single change is the quickest way to recognise the two chords by ear.
Open A# major →Good questions
A#aug questions
What notes are in the A#aug chord?
A#aug contains A#, C## and E##. Counted from the root, that is the formula 1 · 3 · ♯5, or 4 and 8 semitones above A#.
What is the right-hand fingering for A#aug?
A comfortable beginner fingering is 1 (thumb) on A#, 3 (middle finger) on C## and 5 (little finger) on E##. Finger numbers run from the thumb (1) to the little finger (5), and they change once you start using inversions.
How is A#aug different from A# major?
A#aug and A# major share A# and C##. Moving the perfect fifth E# up 1 semitone to the augmented fifth E## turns A# major into A#aug.
Which keys use the A#aug chord?
It occurs naturally in G harmonic minor (III+). The roman numeral shows which degree of the key the chord is built on.
What are the inversions of A#aug?
root position is A# – C## – E##, first inversion is C## – E## – A# and second inversion is E## – A# – C##. Every inversion holds the same notes; only the lowest one changes.
Is A#aug the same as the B♭ chord?
On an equal-tempered piano A# and B♭ are the same key, so the chords sound identical. Written music chooses between them according to the key signature: pages here are named after the sharp spelling of the root, and the chord tones are then spelled by the degree each one occupies, which is why a double sharp occasionally appears.