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The Aaug chord

The Aaug (A - C# - F) is a augmented triad, which is why it sounds off-balance in a deliberate way. Writers pick it for a moment of weirdness, and you can find it across Beatles bridges and James Bond themes. On guitar the chord sits right under the fingers in open position; on piano it stacks straight up under the right hand. The page below covers the voicings worth memorising, the theory, the progressions where the Aaug earns its keep, and the records that lean on it.

Hear the Aaug in the chord builder →

Voicings for Aaug

Common ways to grip the Aaug on guitar and piano. Guitar diagrams read low E to high E left-to-right; an × means muted, an open circle above the nut means an open string. Filled dots are fretted notes.

Guitar , full chord shapes

CAGED-derived voicings for Aaug across the neck. Pick the shape closest to where your hand already sits.

Guitar: A-string aug
Notes: A - C# - F (chord tones)
Guitar: E-shape aug at fr.5
Notes: A - C# - F (chord tones)
Guitar: D-string aug at fr.7
Notes: A - C# - F (chord tones)
Guitar: top-4 voicing
Notes: A - C# - F (chord tones)

Guitar , triad shapes

Three-note triad shapes on each string set, shown moving up the neck. Light textures for arpeggios, pop layering and chord-melody work.

Triad: top strings (G-B-e) · fr.1
Notes: top-string triad, fr.1
Triad: top strings (G-B-e) · fr.5
Notes: top-string triad, fr.5
Triad: top strings (G-B-e) · fr.9
Notes: top-string triad, fr.9
Triad: middle strings (D-G-B) · fr.2
Notes: middle-string triad, fr.2
Triad: middle strings (D-G-B) · fr.6
Notes: middle-string triad, fr.6
Triad: middle strings (D-G-B) · fr.10
Notes: middle-string triad, fr.10
Triad: bass strings (A-D-G) · fr.2
Notes: bass-side triad, fr.2
Triad: bass strings (A-D-G) · fr.6
Notes: bass-side triad, fr.6
Triad: bass strings (A-D-G) · fr.10
Notes: bass-side triad, fr.10

Piano voicings

Root position and inversions. The bass note matters: each inversion changes how the chord sits under a melody.

Piano: root position
Notes: A - C# - F. Root A at the bottom. The classic stacked-thirds spelling of a augmented triad.
Piano: first inversion
Notes: C# - F - A. C# at the bottom. Common in chord-melody, walking bass lines and gentler voicings.
Piano: second inversion
Notes: F - A - C#. F at the bottom. A floating, suspended feel often used in hymns and ballads.

The theory behind Aaug

Aaug is a augmented triad built on A. Its three or four notes (A - C# - F) sit a specific distance apart: root, major third, augmented fifth. That makes it a passing chord in the key of a closely related major key, and the same chord works as the passing chord in a closely related major key. The simplest rule of thumb: the Aaug wants to resolve up a half-step into the next major chord.

Progressions that use Aaug

Short progressions that put the Aaug to work. Each one is shown in a different key so you can pick the one that suits your singer.

IIVV key of C major
Aaug (as passing colour)

This chord appears as a borrowed or passing chord in many major-key progressions.

→ Build this in the chord builder

Songs that feature Aaug

Real records where this chord does structural work. No lyrics quoted, just the title and artist so you can pull up a copy and hear it in context.

Related chords

Chords a step away from the Aaug in the songwriting circle, the natural neighbours when you want a substitution.

Keys where Aaug lives

The keys where this chord turns up diatonically. Open any key page for the full set of progressions that lean on it.

Related references

Other ways to put the Aaug to work across the reference library.

More songwriting tools

Got the chord but still wrestling with the lyric? Find the right rhyme in RhymeForge, or break a writer's block with the unexpected word-pair generator in CollisionLab. Need to map a full progression? The chord builder on the home page is where the Aaug fits into context. All free, no signup.

About the chord builder

The Undercover Zest chord progression builder is a free interactive tool that maps every diatonic and borrowed chord in every key. Click a Roman numeral to hear it, drag chords into a progression, then audition voicings, inversions and tensions until the song clicks.

This page is a static reference for the Aaug. For interactive playback, voice-leading hints and substitution suggestions, open the chord builder above.