Augmented Chords: How They Work and How Composers Use Them

What Is an Augmented Chord?

A major triad is a major third with a minor third on top: C–E–G. A minor triad is the reverse. Both are built from a pair of opposite thirds. An augmented triad is built from two matching major thirds: C–E–G♯. Its fifth is a half step higher than a perfect fifth — an augmented fifth, which gives the chord its name — and it is written Caug or C+.

That structure has a consequence that shapes everything else. Because every interval in the chord is a major third, the chord is perfectly symmetrical: C–E–G♯, E–G♯–C and G♯–C–E are all the same three notes, and any of them could be the root. Diminished chords share this property in miniature (two minor thirds), which is why the two are usually taught together — see our guide to diminished chords — but where the diminished triad feels compressed and tense, the augmented triad, built from wider thirds, feels expansive.

Both chords are also, in a sense, basic: they are simply the two remaining ways to stack thirds. But they are drastically less common than major and minor chords, and that rarity is a large part of their effect. Used sparingly, an augmented chord is a colour we do not hear often, and the ear notices.

Why It Sounds the Way It Does

Three things give the augmented chord its character.

No perfect fifth. The perfect fifth is what makes a major or minor triad feel grounded. Replace it with an augmented fifth and the floor disappears; the raised fifth has a distinctly sharp sound, and the chord seems to float.

Symmetry. Because any note can be the root, the ear cannot settle on where the chord is centred. Three augmented triads — C+, E+ and G♯+ — are the same chord. That ambiguity is what makes augmented chords a little harder to catch by ear, and what gives them their elusive, slippery quality.

The whole-tone scale. Build a scale entirely from whole steps — C–D–E–F♯–G♯–A♯ — and the triad you get from it is augmented. The whole-tone scale and the augmented chord are two faces of the same sound: run the scale on a harp over an augmented chord and you have a texture that reads instantly as magic. Write an entire passage from augmented chords, and the melody has to be whole-tone too; the parallel motion that results sounds strange, mysterious and, in a full orchestra, like outer space.

Debussy was the pioneer of both sounds, and the augmented chord is one of several ideas — along with chordal voicings and borrowed chords — that modern Japanese composers such as Joe Hisaishi and Ryuichi Sakamoto inherited from French impressionism and developed further.

Two Jobs in Functional Harmony

In tonal writing, the vast majority of augmented chords do one of two things.

As an altered dominant

The augmented triad most often appears on the V chord. Raise the fifth of G major and you get G–B–D♯: G+, or V+. It still has a dominant function and still wants to resolve to I; what changes is the colour, which is crunchier and more dissonant than the plain V. If you are training your ear, this is worth knowing: when a chord sounds augmented, it is most likely the V, so listen for the fifth degree of the key in the bass, then for that sharp raised fifth above it.

Add a minor seventh and you get the augmented seventh chord: G–B–D♯–F, written G+7 or G7♯5. Now there is a tritone between the B and the F, and the ear starts itching for it to resolve — a real sense of restlessness and urge to move on. Two details matter here. First, the augmented seventh chord is no longer symmetrical, so it loses the triad's flexibility and behaves like any other dominant. Second, "augmented seventh" almost always means this dominant version; if you want a major seventh on top (G–B–D♯–F♯), you have to say augmented major seventh.

One distinction trips people up. A raised fifth (♯5) and a flat thirteenth (♭13) are the same pitch, but not the same thing. It is only a ♭13 if the regular fifth is also present in the chord. Take the fifth away and what you have is an augmented chord. So V+7 has only the raised fifth; V7♭13 has both.

As a passing chord

The other common job is to connect two harmonies with a smooth chromatic line. Because the augmented chord shares two notes with the major triad on the same root, you can hold those two notes and move the third by a half step: C–C+–Am/C–C7, with the top voice climbing G–G♯–A–B♭ while the C stays put. Or go the other way: C–B+–Gm/B♭, with the common tone held while the bass descends. In both cases the music passes through several harmonies while one note stays constant, and the augmented chord is the hinge.

The same move works from a minor chord. Start on A minor (A–C–E) and move to C+ (C–E–G♯): only one pitch has changed, and the chord has become something elusive. That is the sneaking quality of magic — things slipping, not quite what they seemed — produced by a single half step.

The Legend of Otoe: Levels 2 & 3 Diminished and augmented chords, altered dominants, non-functional harmony and impressionist colour, with a full sketch written in every level. Explore the course

One Augmented Triad, Six Keys

The symmetry has a practical payoff. Because any note of an augmented triad can be its root, any augmented triad is potentially the V+ of three different keys — and each of those can be major or minor. C+ is the same chord as E+ and G♯+, so it can resolve to F or F minor, to A or A minor, and to C♯ or C♯ minor. One chord, six possible destinations.

In practice this makes the augmented triad an excellent pivot. Arrive on one, and the listener has no way of knowing which of the six doors you will leave by. If you want a modulation to feel sudden but still logical, an augmented chord that both keys can claim is one of the cleanest ways to do it. The voice leading is simple in every case: the third of the augmented chord is the leading tone of the new key and rises by a half step, while the raised fifth either rises into the major third or, respelled, already is the minor third and stays put. E+ into A major moves G♯ to A and C to C♯; E+ into A minor moves only G♯ to A, and the C stays. That is why a C+ chord, with its G♯ straining upward, can be heard as the V of F: the E rises to F, and the G♯ becomes A in F major or remains as A♭ in F minor.

The Sound of Magic: Augmented Chords as Colour

Outside functional harmony, the augmented chord stops being a signpost and becomes the sound itself. This is where media composers use it most.

Magic and mystery. In the "magic" style of fantasy scoring, augmented chords are often not passing chords on the way somewhere else — they are the world the music lives in. Sustain one, arpeggiate it, or run a whole-tone scale over it, and the result is mysterious, odd and suspenseful: something is going on here. Combined with chromatic mediants, diminished chords and planing, it is one of the four harmonic ingredients of the wizard sound — though using an augmented chord alone does not make anything sound like wizards. Style is the combination of harmony, melody, rhythm and instruments, and the augmented chord is one piece of it.

Late-Romantic colour. Chained augmented chords moving chromatically have an old-timey, turn-of-the-century quality — the chromaticism of late-Romantic music. It is worth knowing that reference so you can lean into it or avoid it.

A vibe to sit in. In a dark cave sketch, the B section can be built on nothing more than a single augmented triad, laid out as whole notes, with the A section's figure played over it in the same shape but on the new pitches. Four bars of one chord, repeated, because it is simply a mood — and because by the B section you should be playing with material you have already set up, not inventing new things.

Layered tension. In a villain theme, layering an augmented chord on top of a minor chord — an E+ over G minor, for instance — increases the tension beyond what the plain minor harmony gives you. The two chords share nothing, and the friction is the point.

A twist at the cadence. If a phrase is expected to end on a plain major chord, end it on the augmented version instead: B♭+ where the ear expects B♭. The chord still arrives where it should, so the cadence works, but the raised fifth leaves it hanging for a moment. Use it once and it is a surprise; bring it back at a later cadence and it becomes a small identifying mark of the piece.

Comedy. Because the chord sounds slightly wrong, it reads as mischief when the orchestration is light. A short pizzicato figure in the strings with a triangle on the off-beats, harmonized with augmented chords rather than the expected diatonic ones, sounds like tiptoeing — something sneaking rather than something threatening. The same chords under sustained low strings would sound eerie; the lightness of the scoring is what turns weird into funny.

Composing Worlds: Wizards & Witches The harmony, melody, rhythm and orchestration of magical fantasy scoring — augmented chords, chromatic mediants and planing, applied in a complete sketch and mock-up. Explore the course

Augmented Chord or Augmented Sixth?

One source of confusion is worth clearing up. Augmented sixth chords are not augmented chords. They are a family of chromatic chords from eighteenth- and nineteenth-century harmony — Mozart, Beethoven and Schubert use them constantly — built on the flat sixth degree of the key. What defines them is the interval of an augmented sixth between the bass and an upper voice: in C major, A♭ in the bass against F♯ above it. That interval resolves outward, both voices moving by half step to G, so the chord leads straight into the dominant. The three classical types differ only in the middle notes: the Italian sixth adds the third (A♭–C–F♯), the French adds the second (A♭–C–D–F♯), the German adds the fifth (A♭–C–E♭–F♯).

In C major, the German sixth (A♭–C–E♭–F♯) happens to contain the same four notes as an A♭ dominant seventh (A♭–C–E♭–G♭). In jazz terms, A♭7 is the tritone substitute for D7, the dominant of G, and it resolves to G in exactly the same way, by half step in the bass. So the classical German sixth of C major and the jazz tritone substitution of C major's V/V arrive at the same chord doing the same job, described in two different vocabularies a century and a half apart. The so-called Blackadder chord of anime harmony has been proposed as a fourth member of the family, a Japanese augmented sixth. All of these share a name with the augmented triad only because both contain an augmented interval; they are different chords doing different jobs. Our tritone guide covers the substitution side of the story.

Common Mistakes

• Confusing ♯5 with ♭13. They are the same pitch. It is only a ♭13 if the natural fifth is also in the chord; otherwise you have an augmented chord.
• Expecting symmetry from the seventh chord. The augmented triad can be any of three roots; add a seventh and that flexibility is gone.
• Using it everywhere. The chord is rare, and its effect depends on that. One augmented moment in a phrase reads as magic; a phrase full of them reads as a whole-tone exercise.
• Forgetting the melody. Over an augmented chord the melody needs to live in the whole-tone scale or on chord tones; a diatonic melody will fight the raised fifth.
• Mixing up augmented chords and augmented sixths. Different chords, same adjective.

For the wider harmonic context, see our complete guide to chord progressions for composers and our guide to diminished chords, the augmented chord's symmetrical sibling.