A Diminished Seventh Chord

Chord Tones: A Diminished Seventh Chord

Symbol: dim7, °7 — 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 A diminished seventh chord commonly functions as the submediant (vi) in C major or dominant (V) in D major. Its harmonic role varies by key — in major keys it provides extended harmonic tension.

The diminished seventh chord consists of four equally-spaced minor thirds, creating a symmetrical, highly dissonant chord. It is used as a dramatic pivot chord and in chromatic passing harmony. The A Diminished Seventh Chord specifically contains 4 notes: A, C, D♯, F♯ (formula: 1-♭3-♭5-𝄫7). On guitar, A-rooted chords anchor to the open A string (5th string), and barre chord shapes rooted on A form the basis of the "A-shape" CAGED system. Blues, rock, and country music use A-rooted chords extensively — the classic 12-bar blues often starts on A, and many rock power chord riffs center on the open A string.

Common Progressions

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

• viidim7-I
• sharpivdim7-V

Songs Featuring the Diminished Seventh Chord

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

• While My Guitar Gently Weeps – Beatles
• Georgia on My Mind – Ray Charles
• Sophisticated Lady – Duke Ellington

Tuning Frequencies Across Temperaments

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

Scales Containing the A Diminished Seventh Chord

These scales include the A Diminished Seventh Chord as a diatonic or characteristic chord: