C Augmented Seventh Chord

Chord Tones: C Augmented Seventh Chord

Symbol: aug7, +7, 7♯5 — Formula: 1-3-♯5-♭7

Chord Notation

Roman numeral (e.g. I, IV, V) and Nashville Number notation are key-dependent. See Keys pages for chord function within specific keys.

Inversions

Harmonic Function

The C augmented seventh chord commonly functions as the tonic (I) in C major/minor. Its harmonic role varies by key — in major keys it provides extended harmonic tension.

The augmented seventh chord adds a minor seventh to the augmented triad, combining the restlessness of an augmented fifth with the tension of a dominant seventh. Used for maximum harmonic tension. The C Augmented Seventh Chord specifically contains 4 notes: C, E, G♯, A♯ (formula: 1-3-♯5-♭7). On piano, C-rooted chords sit entirely on white keys in their basic triad form, making them the first chords most students learn. Pop, folk, and singer-songwriter music heavily use C-rooted chords because open-position guitar voicings and piano shapes are immediately accessible.

Common Progressions

The C Augmented Seventh Chord frequently appears in these progression patterns (shown in Roman numeral notation relative to key):

• Vaug7-I
• Iaug7-IV

Songs Featuring the Augmented Seventh Chord

Well-known songs where the C Augmented Seventh Chord — or this chord type — plays a prominent role:

• Whole Lotta Love – Led Zeppelin
• Come Together – Beatles (chord variant)
• Spanish Key – Miles Davis

Tuning Frequencies Across Temperaments

Frequencies shown at A=440 Hz. View full temperament data for any note.

Scales Containing the C Augmented Seventh Chord

These scales include the C Augmented Seventh Chord as a diatonic or characteristic chord: