Aaug: A 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	white	thumb (1)	little finger (5)
C♯	black	middle finger (3)	middle finger (3)
E♯	white	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 (Aaug/C♯)
C♯ – E♯ – A
2nd inversion (Aaug/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:

C♯ Augmented→F Augmented→

A Augmented : Frequently Asked Questions

What notes are in Aaug?

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

How do you play Aaug on piano?

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

What are the inversions of Aaug?

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

What is the difference between Aaug and Aaug7?

Adds G. 3 of the notes are shared.

What is an easy Aaug for small hands?

The root and third only voicing, A3 C♯4, spans 4 semitones or about 55 mm.

What are the frequencies of Aaug?

From A3 at A440 in 12-TET: 220.00, 277.18, 349.23 Hz.

What is the set class of Aaug?

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

How do I transpose Aaug to another key?

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

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	A3 C♯4 E♯4	8	110 mm	none	identical
Close, first inversion	C♯4 E♯4 A4	8	110 mm	none	identical
Close, second inversion	E♯4 A4 C♯5	8	110 mm	none	identical
Open, fifth on top	A2 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	A3 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	A3, C♯4, E♯4	5/3	8	110 mm
First inversion: Aaug/C♯	C♯	C♯4, E♯4, A4	6/3	8	110 mm
Second inversion: Aaug/E♯	E♯	E♯4, A4, 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
Aaug7	adds G	1 3 ♯5 ♭7	3
A	E♯ becomes E	1 3 5	2
Amaj7	E♯ becomes E, G♯	1 3 5 7	2
A7	E♯ becomes E, G	1 3 5 ♭7	2
A6	E♯ becomes E, F♯	1 3 5 6	2
Aadd9	E♯ becomes E, B	1 3 5 9	2
Am	C♯, E♯ becomes C, E	1 ♭3 5	1
Adim	C♯, E♯ becomes C, E♭	1 ♭3 ♭5	1
Asus2	C♯, E♯ becomes B, E	1 2 5	1
Asus4	C♯, E♯ becomes D, E	1 4 5	1

Frequencies

Note	MIDI	Frequency
A3	57	220.00 Hz
C♯4	61	277.18 Hz
E♯4	65	349.23 Hz

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

Set theory: prime form, Forte number, interval vector

Absolute pitch class set: {9, 1, 5}
Normal order: [1, 5, 9]
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