Augmented
aug
0 - 4 - 8Root + major 3rd + augmented 5th
About Augmented
An augmented chord is a three-note chord built from a root, a major third and an augmented fifth — in C that is C, E and G♯, written Caug, C+ or C♯5. It divides the octave into three equal parts, and that perfect symmetry is both what makes it strange and what makes it useful.
Notes and formula
The formula is 1 – 3 – ♯5, or 0 – 4 – 8 in semitones: two major thirds stacked. C to E is four semitones, E to G♯ another four, and G♯ back to C a third four.
Because all three gaps are equal, the chord has no bottom. C–E–G♯, E–G♯–C and A♭–C–E are the same four-semitone stack starting in different places, so an augmented triad on C is also one on E and one on A♭. There are only four distinct augmented chords in all of music.
How to play it
On piano the chord is C–E–G♯, and the sharpened fifth is the only note that moves from a plain C major.
On guitar the open form is x32110 — an open C major with the second string raised a fret. Because the shape is symmetrical, sliding it three frets up gives the same chord again under a different name, which is a fast way to reach an augmented chord anywhere on the neck.
What it does
An augmented chord belongs to no ordinary key: build triads on a major scale and not one of them comes out augmented. It arrives instead as an alteration, almost always as a major chord whose fifth is on its way somewhere — usually up a semitone to the sixth degree, occasionally down again.
That single moving voice is the whole effect. C to Caug to F is a chord change in which only G moves, to G♯ and then to A, and the ear follows the line rather than the harmony. Roy Orbison built the opening of Crying on it, the Beatles used it to lead into Oh! Darling, and it remains standard in film scoring for the same reason: it makes a change of scene sound continuous.
Where you hear it
Beyond the classic passing use it appears as a dominant with a raised fifth — the augmented seventh chord, which is this triad plus a minor seventh — and there it points hard at the chord a fourth away.
In jazz and in impressionist writing the symmetry itself is the attraction: an augmented triad belongs equally to two whole-tone scales, so composers use it when they want harmony to lose its sense of gravity for a bar or two. Debussy uses it that way constantly.
Augmented or diminished
The names sound like opposites, and structurally they are: one stacks major thirds, the other minor thirds; one stretches the fifth by a semitone, the other shrinks it. Both are symmetrical and neither belongs to a plain major key.
They behave differently, though. A diminished chord is a dominant in disguise and resolves inward; an augmented chord is a major chord with a rising line inside it and resolves outward. Hearing which is which is easier than reading it: the augmented sound is bright and unresolved, the diminished one dark and unresolved.
Scales that contain it
The whole-tone scale — six notes, each a tone apart — contains the chord and nothing that contradicts it, which is why it is the default choice for improvising over one. There are only two whole-tone scales, and an augmented triad belongs to one of them.
The harmonic minor scale produces the chord on its third degree, and that is where augmented triads appear in written music without any alteration at all: in C minor with a raised leading tone, E♭–G–B is an augmented triad by construction.
Frequently asked questions
What notes are in a C augmented chord?
C, E and G♯ — a C major chord with the fifth raised a semitone. On guitar it is x32110.
Why do Caug, Eaug and A♭aug sound the same?
They contain the same three notes. Because the chord is built from equal four-semitone steps, any of its notes can be called the root, so the three names describe one sound in three contexts.
When would I use an augmented chord?
Most often between a major chord and the chord a fourth above it, to move the fifth up by semitones — C, Caug, F. It is a connector, and it works because only one voice changes.