Augmented Chords Explained: Theory, Notation, and Practical Use

Augmented chords are three-note chords (triads) consisting of a root, a major third, and an augmented fifth. They produce a bright, tense, and somewhat dreamlike quality, often used to create harmonic instability and smooth chromatic transitions. This article explores their construction, notation, variations, and iconic uses across genres.

Quick Facts

Etymology / Origin

The term “augmented” derives from the Latin augmentare, meaning “to increase.” In music theory, it refers to the raising (augmenting) of a perfect interval by a semitone. The augmented triad first appeared as a chromatic alteration in the common practice period, often as a byproduct of voice leading. It gained prominence in the Romantic era (e.g., Liszt, Wagner) and became a staple in Impressionist music (Debussy, Ravel) due to its symmetrical structure and ambiguity. The chord’s inherent tension made it a favorite in 20th-century jazz and film scoring.

How It Works

An augmented chord is built by stacking two major thirds. For example, a C augmented chord (Caug) contains the notes C, E, and G♯. The interval between C and E is a major third (4 semitones), and between E and G♯ is also a major third. This symmetry means the chord divides the octave into three equal parts, and any inversion of an augmented chord is itself an augmented chord (e.g., C aug = E aug = G♯ aug). Because of this, there are only four distinct augmented chords in 12-tone equal temperament.

The augmented fifth creates a strong sense of instability. The chord naturally resolves by moving any of its tones up or down a half step, often to a major or minor chord. For instance, C aug (C–E–G♯) can resolve to F major (C–F–A) or A minor (C–E–A) by moving the G♯ to A. This chromatic voice leading makes augmented chords powerful tools for modulation and adding color to progressions.

Notation & Diagrams

Augmented chords are notated in several ways:

• Chord symbols: Caug, C+, C+5, C(♯5)
• Roman numerals: III+ (in minor keys, e.g., E♭+ in C minor)
• Lead sheet notation: C aug

Piano diagram (C augmented): Play C with the left hand, and E–G♯–C with the right. The chord can be voiced in any inversion.

Guitar tab (C augmented, open position):

e|---0---
B|---1---
G|---1---
D|---2---
A|---3---
E|---x---

This voicing (x-3-2-1-1-0) produces C–E–G♯–C–E, doubling the root and third. Other common shapes include the barre chord at the 3rd fret (3-2-1-1-1-x) for G♯ aug.

Step-by-Step / How to Play

1. Choose a root note. For example, C.
2. Add a major third above the root. Count 4 semitones up from C to E.
3. Add an augmented fifth. Count 8 semitones up from C to G♯ (or 4 semitones above the third).
4. On piano: Play the three notes simultaneously. Experiment with inversions (E–G♯–C, G♯–C–E).
5. On guitar: Find a voicing that includes the root, major third, and augmented fifth. The open C aug shape is a good start. Move the shape up the neck for other roots.
6. Practice voice leading: Resolve the augmented fifth up a half step to a consonant chord (e.g., C aug to F major).

Common Variations

• Augmented major seventh (Caugmaj7): C–E–G♯–B. Adds a major seventh, creating a lush, mysterious sound (used in jazz and film noir).
• Augmented dominant seventh (Caug7 or C+7): C–E–G♯–B♭. Functions as an altered dominant, often resolving to F major or F minor.
• Augmented sixth chords: Italian (It+6), French (Fr+6), German (Ger+6). These are enharmonic equivalents of dominant seventh chords, used for pre-dominant function in classical music.
• Whole-tone harmony: The augmented triad is the basic building block of the whole-tone scale, where any chord built in thirds is augmented.

Common Mistakes

• Confusing augmented with diminished: Diminished chords have a minor third and diminished fifth (e.g., Cdim: C–E♭–G♭). Augmented chords have a major third and augmented fifth.
• Mislabeling the root: Because of symmetry, a chord like C–E–G♯ could be labeled C aug, E aug, or G♯ aug. Always consider the harmonic context to determine the correct root.
• Overusing the chord: Augmented chords are highly chromatic; using them too frequently can make the harmony sound aimless. Use them sparingly for maximum impact.
• Poor voice leading: The augmented fifth should resolve smoothly, typically by step. Avoid awkward leaps that break the voice-leading logic.

Notable Examples in Songs

• “Oh! Darling” – The Beatles
• “Life on Mars?” – David Bowie
• “The Entertainer” – Scott Joplin
• “Stairway to Heaven” – Led Zeppelin
• “Giant Steps” – John Coltrane
• “Clair de Lune” – Claude Debussy