C#aug

Q: What notes are in the C#aug chord?

The C#aug chord (C# Augmented) contains: C#, E#, A. Its interval structure is shown above in the Theory section.

Q: How do I build C#aug on the keyboard?

Take the root and add the remaining chord tones following the interval formula. The highlight shows chord content, while the inversion control changes which chord tone is in the bass.

Q: Which keys is C#aug found in?

The chord acts as a diatonic degree in several keys — they are marked on the circle of fifths in the "Harmonic context" block.

Q: What can I substitute for C#aug?

A substitution depends on harmonic function and voice leading, not only on shared tones. Computed options appear in the "Substitutions" block and should be checked in context.

C# Augmented

Octaves

Musical context

ChordC#augC# Augmented

ArpeggioC# majorBroken triad

ScaleC# major7 notes

KeyC# majorMajor key

ProgressionPop axisSequence

How the chord relates to the scale, mode, key and progression.

Theory

General info

Full name: C# Augmented
Symbol: C#aug
Root: C#
Quality: Augmented

Chord notes

1C#root

3E#major 3rd

#5Aaug 5th

Functions & resolutions

Typical function in key: vii°Leading tone (vii°)D major
Stability / tension: Marked tension — unstable, seeks resolution
Most common resolutions: C#C# Major F#F# Major
Unstable degrees: #5A
6A#
resolves up to the 6th
Main resolution: C#augsource
C#C# Major
Augmented C#aug has a raised 5th. As a dominant it resolves up a 4th — the raised 5th rising a semitone. Returning to the major of the same root, it instead falls back to a perfect 5th.
Other resolutions: C#augsource
Deceptive resolution
C#mC# Minor
An augmented chord can resolve to the minor chord of the same root: the raised 5th falls to a perfect 5th and the major 3rd lowers to a minor 3rd.
C#augsource
No resolution needed
In a whole-tone context, the augmented chord can be used as a color chord — without mandatory resolution.
C#augsource
Jazz reharmonization
F#F# Major
In jazz, aug often acts as a dominant with raised 5th, resolving up a 4th as a V7 substitute.
C#augsource
Functional resolution
FF Major
Due to its symmetry (equal intervals), an augmented chord can resolve to chords a major 3rd apart.

Bbmharmonic minor

C#augdegree III

The raised 7th of harmonic minor makes the III triad augmented — C#aug arises within the key on its own.

C#augV+

F#resolution

As a dominant it resolves a fourth up: the raised fifth (A) rises a semitone into the tonic's third (Bb).

Features

Character: Augmented, symmetric and unstable
Characteristic interval: Augmented 5th (#5)
Description: The augmented fifth (#5) is raised a semitone above normal. The chord is symmetric — all three notes are equidistant by major thirds.
Application: Chromatic passing
III in harmonic minor
Unexpected colors

Voicing & structure

Root position

v1C#(C#4)Bass

root

v2E#(E#4)M3from C#

v3A(A4)M3from E#

Harmony

Compatible scales

All chord tones are contained in these scales — use them for improvisation.

ScaleC# Whole tone scale ScaleC# Augmented scale ScaleF Whole tone scale ScaleF Augmented scale ScaleA Whole tone scale ScaleA Augmented scale ScaleD Augmented scale ScaleD# Whole tone scale ScaleF# Augmented scale ScaleG Whole tone scale

This chord on guitar 🎸

See how C#aug looks on guitar.

Explore

Circle of fifths

Highlighted major keys contain this chord among their diatonic harmonies.

Relative key: BbmBb minor
Dominant: AbAb major
Subdominant: F#F# major
Key signature: 5 flats (Bb, Eb, Ab, Db, Gb)

What to learn next

ScaleC# Chromatic scaleScale to improvise over this chord ChordC# MajorA nearby chord on the same root — compare the sound PracticeChord trainerLock the fingering into muscle memory ProgressionChord progressionsHow this chord works inside real progressions ChordC# Dominant 7Another related chord to practise

Recommended for you

C# MajorA chord that sounds close

C# Dominant 7A chord that sounds close

C# Chromatic scaleA scale related to this chord

C# Persian scaleA scale related to this chord

C# ByzantineA scale related to this chord

Practice

Keyboard Trainer

Reinforce it in practice — play and name notes on the interactive keyboard.

Open Trainer

Test yourself

(Press any key to start)

What notes are in the C#aug chord?

How do I build C#aug on the keyboard?

Which keys is C#aug found in?

What can I substitute for C#aug?