A♯aug: A♯/B♭ Augmented Piano Chord

Root position: either hand, fingers low note to high
Hand	Notes	Fingers
Right	A♯, C×, E×	1-3-5
Left	A♯, C×, E×	5-3-1

Scale degree, note, and interval measured from the root.
Degree	Note	Interval from root	Semitones
1	A♯	Perfect unison	0
3	C×	Major third	4
♯5	E×	Minor sixth	8

Construction

A♯ Augmented = Root + Major 3rd + Minor 6th = A♯, C♯♯, E♯♯

Note	Interval	Degree
A♯	Root	1
C♯♯	Major 3rd	3
E♯♯	Minor 6th	♯5

Fingering

Note	Key color	Right hand	Left hand
A♯	black	thumb (1)	little finger (5)
C♯♯	white	middle finger (3)	middle finger (3)
E♯♯	black	little finger (5)	thumb (1)

Right hand: thumb (1) on A♯, middle finger (3) on C♯♯, little finger (5) on E♯♯.

Left hand: little finger (5) on A♯, middle finger (3) on C♯♯, thumb (1) on E♯♯.

A♯ Augmented Inversions

Root position
A♯ – C♯♯ – E♯♯
1st inversion (A♯aug/C♯♯)
C♯♯ – E♯♯ – A♯
2nd inversion (A♯aug/E♯♯)
E♯♯ – A♯ – C♯♯

Key Signature

A Augmented chord is built from symmetrical or ambiguous intervals, so it doesn't belong to a single key and has no key signature of its own.

Chords in the Key of A♯ Major

These are the triads built on each degree of A♯ Major:

I — A♯ Major (major)

Degree	Numeral	Chord	Quality
1	I	A♯ Major	Major
2	ii	B♯ Minor	Minor
3	iii	C♯♯ Minor	Minor
4	IV	D♯ Major	Major
5	V	E♯ Major	Major
6	vi	F♯♯ Minor	Minor
7	vii°	G♯♯ Diminished	Diminished

Same Notes, Other Names

The notes A♯ – C♯♯ – E♯♯ aren’t exclusive to this chord. Depending on which note is the bass and how the chord functions, the same pitches also spell the following:

D Augmented→F♯ Augmented→

A♯ Augmented : Frequently Asked Questions

What notes are in A♯aug?

A♯aug contains A♯, C× and E×. The formula is 1, 3, ♯5.

How do you play A♯aug on piano?

Play A♯, C× and E× together. Right hand fingers 1, 3, 5; left hand 5, 3, 1. A♯ and E× are black keys; C× is white.

What are the inversions of A♯aug?

3 positions: root position A♯ C× E×, A♯aug/C×, A♯aug/E×.

What is the difference between A♯aug and A♯aug7?

Adds G♯. 3 of the notes are shared.

What is an easy A♯aug for small hands?

The root and third only voicing, A♯3 C×4, spans 4 semitones or about 55 mm.

What are the frequencies of A♯aug?

From A♯3 at A440 in 12-TET: 233.08, 293.66, 369.99 Hz.

What is the set class of A♯aug?

Prime form (048), Forte 3-12, interval vector <000300>.

How do I transpose A♯aug to another key?

Keep the 1, 3, ♯5 formula on the new root. Caug is C, E, G♯; D♭aug is D♭, F, A.

Is B♭aug the same as A♯aug?

Enharmonically yes: the same piano keys and the same sound, spelled differently.

A♯ Augmented in detail

Exact

Every pitch class is present and nothing outside the chord is added.

Type	Notes	Semitones	Span	Omissions and additions	Set relation
Close, root position	A♯3 C×4 E×4	8	110 mm	none	identical
Close, first inversion	C×4 E×4 A♯4	8	110 mm	none	identical
Close, second inversion	E×4 A♯4 C×5	8	110 mm	none	identical
Open, fifth on top	A♯2 E×3 C×4	16	220 mm	none	identical

Reduced

A subset of the pitch classes: the identity is incomplete rather than altered.

Type	Notes	Semitones	Span	Omissions and additions	Set relation	Fit
Root and third only	A♯3 C×4	4	55 mm	omits E×	subset

Spans are measured centre to centre at a 165 mm octave (standard keyboard geometry).

Position	Bass note	Notes in order	Figured bass	Semitones	Span
Root position	A♯	A♯3, C×4, E×4	5/3	8	110 mm
First inversion: A♯aug/C×	C×	C×4, E×4, A♯4	6/3	8	110 mm
Second inversion: A♯aug/E×	E×	E×4, A♯4, C×5	6/4	8	110 mm

One position per chord tone in the bass. Spans are for close position: voiced inversions appear under Voicings.

Change one note

Chords a single note away, and what moving that note does.

Chord	Change	Formula	Common tones
A♯aug7	adds G♯	1 3 ♯5 ♭7	3
A♯	E× becomes E♯	1 3 5	2
A♯maj7	E× becomes E♯, G×	1 3 5 7	2
A♯7	E× becomes E♯, G♯	1 3 5 ♭7	2
A♯6	E× becomes E♯, F×	1 3 5 6	2
A♯add9	E× becomes E♯, B♯	1 3 5 9	2
A♯m	C×, E× becomes C♯, E♯	1 ♭3 5	1
A♯dim	C×, E× becomes C♯, E	1 ♭3 ♭5	1
A♯sus2	C×, E× becomes B♯, E♯	1 2 5	1
A♯sus4	C×, E× becomes D♯, E♯	1 4 5	1

Frequencies

Note	MIDI	Frequency
A♯3	58	233.08 Hz
C×4	62	293.66 Hz
E×4	66	369.99 Hz

Reference pitch A440, 12-TET, close root position.

Set theory: prime form, Forte number, interval vector

Absolute pitch class set: {10, 2, 6}
Normal order: [2, 6, 10]
Prime form: (048)
Forte number: 3-12
Interval vector: <000300>

Pair	Interval	Semitones	Interval class
A♯ to C×	Major third	4	4
A♯ to E×	Minor sixth	8	4
C× to E×	Major third	4	4

Where these facts come from

Every value on this page is derived from the note formula for a augmented applied to the root A♯, using standard music theory. Nothing here is hand-entered per chord, so the notes, intervals, inversions and frequencies cannot drift out of agreement with each other. Pitches assume 12-TET at A440.

A♯ Augmented

Fingerings

A♯ Augmented: notes and degrees