# A♯ Diminished 7th piano chord (A♯dim7) A♯dim7 contains A♯, C♯, E and G. Three stacked minor thirds. A♯ and C♯ are black keys; E and G are white. - Canonical page: https://piano.org/chords/diminished-7th/a-sharp/ - Entity: chord:diminished-7th:a-sharp - Notes: A♯ C♯ E G - Formula: 1 ♭3 ♭5 ♭♭7 - Intervals from root: P1, m3, TT, M6 - Interval stack (semitones): 3 3 3 - Also written: A♯dim7, A#dim7, A♯ diminished 7th - Parameters: A440, 12-TET, 165 mm octave, spans centre to centre ## Construction | Degree | Note | Interval from root | Semitones | | --- | --- | --- | --- | | 1 | A♯ | Perfect unison | 0 | | ♭3 | C♯ | Minor third | 3 | | ♭5 | E | Tritone | 6 | | ♭♭7 | G | Major sixth | 9 | ## Fingering Rest your right hand over the notes with finger 2 on A♯, finger 3 on C♯, finger 4 on E, finger 5 on G. The left hand mirrors it. Right hand 2-3-4-5, left hand 5-4-3-2. Source: piano.org fingering method v1. ## Inversions | Position | Bass | Notes in order | Figured bass | Span | | --- | --- | --- | --- | --- | | Root position | A♯ | A♯3 C♯4 E4 G4 | 7 | 9 st, 124 mm | | First inversion (A♯dim7/C♯) | C♯ | C♯4 E4 G4 A♯4 | 6/5 | 9 st, 124 mm | | Second inversion (A♯dim7/E) | E | E4 G4 A♯4 C♯5 | 4/3 | 9 st, 124 mm | | Third inversion (A♯dim7/G) | G | G4 A♯4 C♯5 E5 | 4/2 | 9 st, 124 mm | ## Voicings (10) | Voicing | Notes | Span | Relation | Omits or adds | | --- | --- | --- | --- | --- | | Close, root position | A♯3 C♯4 E4 G4 | 9 st, 124 mm | identical | none | | Close, first inversion | C♯4 E4 G4 A♯4 | 9 st, 124 mm | identical | none | | Close, second inversion | E4 G4 A♯4 C♯5 | 9 st, 124 mm | identical | none | | Close, third inversion | G4 A♯4 C♯5 E5 | 9 st, 124 mm | identical | none | | Drop 2 | E3 A♯3 C♯4 G4 | 15 st, 206 mm | identical | none | | Drop 3 | C♯3 A♯3 E4 G4 | 18 st, 248 mm | identical | none | | Drop 2 and 4 | A♯2 E3 C♯4 G4 | 21 st, 289 mm | identical | none | | Shell, root ♭♭7 ♭3 | A♯2 G3 C♯4 | 15 st, 206 mm | subset | omits E | | Guide tones, ♭3 and ♭♭7 | C♯4 G4 | 6 st, 83 mm | subset | omits A♯ and E | | Rootless close | C♯4 E4 G4 | 6 st, 83 mm | subset | omits A♯ | ## One-edit neighbors | Becomes | Edit | Changes | Common tones | | --- | --- | --- | --- | | A♯dim | 1 ♭3 ♭5 | drops G | 3 | | A♯m7♭5 | 1 ♭3 ♭5 ♭7 | G becomes G♯ | 3 | | A♯m6 | 1 ♭3 5 6 | E becomes E♯ | 3 | | A♯m | 1 ♭3 5 | E, G becomes E♯ | 2 | | A♯m7 | 1 ♭3 5 ♭7 | E, G becomes E♯, G♯ | 2 | | A♯mMaj7 | 1 ♭3 5 7 | E, G becomes E♯, G× | 2 | | A♯6 | 1 3 5 6 | C♯, E becomes C×, E♯ | 2 | ## Set theory - Absolute pitch classes: {10, 1, 4, 7} - Relative pitch classes: [0, 3, 6, 9] - Normal order: [1, 4, 7, 10] - Prime form: (0369) - Forte number: 4-28 - Interval vector: <004002> ## Frequencies (close root position) | Note | MIDI | Frequency | | --- | --- | --- | | A♯3 | 58 | 233.08 Hz | | C♯4 | 61 | 277.18 Hz | | E4 | 64 | 329.63 Hz | | G4 | 67 | 392.00 Hz | ## Questions and answers ### What notes are in A♯dim7? A♯dim7 contains A♯, C♯, E and G. The formula is 1, ♭3, ♭5, ♭♭7. ### How do you play A♯dim7 on piano? Play A♯, C♯, E and G together. Right hand fingers 2, 3, 4, 5; left hand 5, 4, 3, 2. A♯ and C♯ are black keys; E and G are white. ### What are the inversions of A♯dim7? 4 positions: root position A♯ C♯ E G, A♯dim7/C♯, A♯dim7/E, A♯dim7/G. ### What is the difference between A♯dim7 and A♯dim? Drops G. 3 of the notes are shared. ### What is an easy A♯dim7 for small hands? The guide tones, ♭3 and ♭♭7 voicing, C♯4 G4, spans 6 semitones or about 83 mm. ### What are the frequencies of A♯dim7? From A♯3 at A440 in 12-TET: 233.08, 277.18, 329.63, 392.00 Hz. ### What is the set class of A♯dim7? Prime form (0369), Forte 4-28, interval vector <004002>. ### How do I transpose A♯dim7 to another key? Keep the 1, ♭3, ♭5, ♭♭7 formula on the new root. C♯dim7 is C♯, E, G, B♭; Ddim7 is D, F, A♭, C♭. ### Is B♭dim7 the same as A♯dim7? Enharmonically yes: the same piano keys and the same sound, spelled differently. ## Provenance Every derived value above is computed by the piano.org theory kernel from the root, the quality and the stated parameters. Nothing is hand-entered per chord. Machine record: https://piano.org/api/knowledge/v1/entities/chord:diminished-7th:a-sharp Last reviewed: 2026-08-12