Augmented Chords Explained
An augmented chord is a major triad with the fifth raised a half step, root, major third and sharp fifth, so Caug is C, E and G#. Two major thirds stacked on top of each other give it a restless, hovering sound that never quite settles, which is exactly why composers reach for it to add tension and lift between more stable chords.
Drill augmented chords by playing them
See an aug chord, play it, know instantly if you nailed it. No download, no signup. MIDI keyboard or microphone.
▶ Try ChordRunner Free Free in the browser - Level 4 is all augmented chords.The symmetric augmented triad
What makes the augmented chord special is its perfect symmetry. Stack a major third on the root, then another major third on that, and you land a sharp fifth: C to E to G#. Every gap is identical, four semitones, so the chord divides the octave into three equal slices. Your ear has no anchor, nothing tells it which note is the root, and that ambiguity is the source of its floating, slightly unsettled character.
That same symmetry has a practical payoff: there are only four augmented chords in all of music. Because Caug, Eaug and G#aug are built from exactly the same three notes, learning one covers three roots at once. Play through them and you will feel the pattern repeat every four semitones.
Build any augmented chord
Pick a root and watch root, major 3rd and sharp 5th light up. Try C, then E, then G# (Ab), the same three keys light every time.
Where augmented chords appear
Augmented chords rarely sit still; they are usually caught mid-motion. The most common use is a rising inner line: hold a C, raise its fifth to make Caug, and that G# wants to climb to the A of an F or C6 chord. That single chromatic step is behind countless dreamy pop turnarounds, the opening of the Beatles' Oh! Darling among them, and the lush lifts in jazz ballads. Spotting that hovering, unresolved quality by ear is a nice chord recognition challenge, because the augmented chord sounds unlike anything stable.
Augmented next to diminished
The augmented triad has a natural opposite. Where augmented stacks two major thirds and stretches the fifth sharp, a diminished chord stacks two minor thirds and squeezes the fifth flat. Both are symmetric, both sound unstable, and both are one altered note away from shapes you already know from chord training. Learning them as a pair, the stretch and the squeeze, makes each easier to remember.
Practise augmented chords in the game
Open the game and play Level 4, which is dedicated to augmented chords, or build a Custom pool of them. Play each on your MIDI keyboard or into your microphone and get told instantly whether the shape was right. Because there are only four distinct augmented chords, they come together fast once you feel the every-four-semitones pattern. Free in the browser, nothing to install.
Common questions
What is an augmented chord?
An augmented chord is a major triad with its fifth raised a half step: root, major third and sharp fifth. In C that is C, E and G#. The two stacked major thirds make it sound tense, dreamy and unstable, like it is hovering rather than resting.
Why are there only four augmented chords?
Because an augmented chord is perfectly symmetric: it is three notes a major third apart, dividing the octave evenly. Caug, Eaug and G#aug all contain the same three notes, just starting from a different one. So the 12 roots collapse into only four distinct augmented chords.
Where are augmented chords used?
As a passing tension. A common move raises the fifth of a chord to walk up into the next one, like C to Caug to C6 or F. They also colour dreamy pop and jazz progressions, and the Beatles used them often, for example the opening of Oh! Darling.
How do I practise augmented chords?
Drill them with instant feedback. In ChordRunner, Level 4 is dedicated to augmented chords, and Custom mode lets you pool them across roots. You play each on a MIDI keyboard or through your microphone and find out immediately whether the shape was right.