3 notes · 1 · 3 · ♯5

C# Augmented Piano Chord (C#aug)

C#aug is built from C#, E# and G## — the formula 1 · 3 · ♯5, or 4 and 8 semitones above C#. The shape uses 2 white and 1 black key, and you can hear it, invert it and compare it below.

Root noteChord type

Chord

C# Augmented

Notes

C# · F · A

Formula

1 · 3 · ♯5

Right hand

1 · 3 · 5

Choose a chord, then play it. Finger numbers run from thumb (1) to little finger (5).

The finder above already holds C#aug. Press P or the Play chord button to hear C#, E#, G## sounded together, then change the root or the chord type to compare it with something else.

Chord tones

The notes in C#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.

Each tone of C# augmented with its interval, scale degree, distance in semitones from C# and a suggested right-hand finger.
Note	Interval	Degree	Semitones	Right hand
C#black key	Root	1	0	1 · thumb
E#white key	Major third	3	4	3 · middle finger
G##white key	Augmented fifth	♯5	8	5 · little finger

Step by step

How to play C#aug on piano

Find C#: it is the first black key in a group of two.
Build upwards from C# using 4 and 8 semitones to reach E# and G##.
With the right hand, place finger 1 on C#, finger 3 on E# and finger 5 on G##. Keep the wrist level and the knuckles rounded.
Move your hand a little further in towards the fallboard so the black key sits comfortably under your fingers.
Play the notes together, then one at a time from the bottom up, and listen to how C#aug settles.
Try first inversion as well: E# – G## – C#. Inversions let you change chords without jumping around the keyboard.

Inversions

C#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.

Root position

C# – E# – G##

The root C# is the lowest note. This is the shape most people learn first.

First inversion

E# – G## – C#

E# is the lowest note, so the major third sits in the bass and the notes below it move up an octave.

Second inversion

G## – C# – E#

G## 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 C#aug

In B♭ 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.

B♭ 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

C#aug against C# major

C#aug and C# major share C# and E#. Moving the perfect fifth G# up 1 semitone to the augmented fifth G## turns C# major into C#aug.

Practise the pair together: hold the shared notes C#, E# still and move only the one finger. Hearing that single change is the quickest way to recognise the two chords by ear.

Open C# major →

Good questions

C#aug questions

What notes are in the C#aug chord?

C#aug contains C#, E# and G##. Counted from the root, that is the formula 1 · 3 · ♯5, or 4 and 8 semitones above C#.

What is the right-hand fingering for C#aug?

A comfortable beginner fingering is 1 (thumb) on C#, 3 (middle finger) on E# and 5 (little finger) on G##. Finger numbers run from the thumb (1) to the little finger (5), and they change once you start using inversions.

How is C#aug different from C# major?

C#aug and C# major share C# and E#. Moving the perfect fifth G# up 1 semitone to the augmented fifth G## turns C# major into C#aug.

Which keys use the C#aug chord?

It occurs naturally in B♭ harmonic minor (III+). The roman numeral shows which degree of the key the chord is built on.

What are the inversions of C#aug?

root position is C# – E# – G##, first inversion is E# – G## – C# and second inversion is G## – C# – E#. Every inversion holds the same notes; only the lowest one changes.

Is C#aug the same as the D♭ chord?

On an equal-tempered piano C# and D♭ 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.