C#aug Chord on Guitar
C#aug = C# – F – A (Root, Major 3rd, Minor 6th)
C#augmented mirrors the diminished chord's symmetry from the opposite direction, stacking major thirds instead of minor ones and raising the fifth by a half step to produce a triad that feels suspended and slightly disoriented rather than clearly major or tense. At the ninth fret, this E-shape barre needs a genuine stretch in the fretting hand, since the raised fifth pushes one finger further from the others than the plain major triad at this position requires.
The notes are C#, F, and A — root, major third, augmented fifth — two major thirds stacked evenly, the mirror image of how diminished chords stack two minor thirds. That symmetry gives augmented triads their characteristic dreamlike, faintly unsettled color, distinct from diminished chords' sharper tension; they're often used as a brief embellishment on a major chord right before it moves elsewhere, the raised fifth acting almost like a chromatic passing note dressed up as a full triad.
Fingerings
Barre (9th fret)
How to Practice It
The stretch to the raised fifth is the main technical hurdle, sitting a half step higher than the same finger would need to reach for a plain major triad — a genuine test of finger independence at a fret position where spacing is already tight. Because augmented chords are typically brief embellishments rather than chords meant to be held, practicing the specific motion of sliding from C# major into C#aug and onward (often to A# minor or F# major) captures how the chord is actually used far better than holding it static.
Common Progressions
- C# – C#aug – F# (I – I+ – IV, a chromatic passing move via the raised fifth)
- C# – C#aug – A#m (an ascending-fifth embellishment resolving to the relative minor)
- F# – C#aug – A#m – D#m (using augmented color as a connective passing chord)
- C# – C#aug – C#6 (a decorative move through the raised and then natural sixth)
FAQ
- Why does C#augmented sound dreamlike rather than harsh?
- Its two stacked major thirds create a symmetrical structure with no single note obviously demanding resolution, producing a floating, ambiguous quality rather than sharp tension.
- How is C#augmented related to C#diminished?
- They're structural opposites — diminished stacks minor thirds and lands below the perfect fifth, while augmented stacks major thirds and lands above it, giving the two a kind of mirror-image relationship despite sounding quite different.
- Why does this fingering demand an extra stretch?
- The augmented fifth sits a half step higher than the plain perfect fifth used in a major triad, pushing that finger further from the rest of the shape.
- How many augmented chords does one shape cover?
- Because augmented triads are also evenly stacked, a single fingering shape covers three different roots a major third apart.
- Where does C#augmented typically get used?
- Most often as a brief chromatic passing chord, raising a major chord's fifth by a half step on the way to another chord a few beats later.
- Is C#augmented ever sustained rather than used briefly?
- Occasionally, particularly in film-score or adventurous jazz writing that wants its floating quality as a deliberate mood, but most guitar-based popular music uses it briefly.
- Is the augmented triad's symmetry ever exploited the way dim7's is?
- Yes, though less often — because it also repeats evenly, the same shape slid in four-fret jumps covers all three roots it can represent, a smaller-scale version of the same trick diminished seventh chords use across three shapes.
C#aug on other instruments: C#aug on Piano. Related: how chords are built, chord finder.