# B♭ Diminished 7th piano chord (B♭dim7) B♭dim7 contains B♭, D♭, F♭ and A♭♭. Three stacked minor thirds. B♭ and D♭ are black keys; F♭ and A♭♭ are white. - Canonical page: https://piano.org/chords/diminished-7th/b-flat/ - Entity: chord:diminished-7th:b-flat - Notes: B♭ D♭ F♭ A♭♭ - Formula: 1 ♭3 ♭5 ♭♭7 - Intervals from root: P1, m3, TT, M6 - Interval stack (semitones): 3 3 3 - Also written: B♭dim7, Bbdim7, B♭ diminished 7th - Parameters: A440, 12-TET, 165 mm octave, spans centre to centre ## Construction | Degree | Note | Interval from root | Semitones | | --- | --- | --- | --- | | 1 | B♭ | Perfect unison | 0 | | ♭3 | D♭ | Minor third | 3 | | ♭5 | F♭ | Tritone | 6 | | ♭♭7 | A♭♭ | Major sixth | 9 | ## Fingering Rest your right hand over the notes with finger 2 on B♭, finger 3 on D♭, finger 4 on F♭, finger 5 on A♭♭. 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 | B♭ | B♭3 D♭4 F♭4 A♭♭4 | 7 | 9 st, 124 mm | | First inversion (B♭dim7/D♭) | D♭ | D♭4 F♭4 A♭♭4 B♭4 | 6/5 | 9 st, 124 mm | | Second inversion (B♭dim7/F♭) | F♭ | F♭4 A♭♭4 B♭4 D♭5 | 4/3 | 9 st, 124 mm | | Third inversion (B♭dim7/A♭♭) | A♭♭ | A♭♭4 B♭4 D♭5 F♭5 | 4/2 | 9 st, 124 mm | ## Voicings (10) | Voicing | Notes | Span | Relation | Omits or adds | | --- | --- | --- | --- | --- | | Close, root position | B♭3 D♭4 F♭4 A♭♭4 | 9 st, 124 mm | identical | none | | Close, first inversion | D♭4 F♭4 A♭♭4 B♭4 | 9 st, 124 mm | identical | none | | Close, second inversion | F♭4 A♭♭4 B♭4 D♭5 | 9 st, 124 mm | identical | none | | Close, third inversion | A♭♭4 B♭4 D♭5 F♭5 | 9 st, 124 mm | identical | none | | Drop 2 | F♭3 B♭3 D♭4 A♭♭4 | 15 st, 206 mm | identical | none | | Drop 3 | D♭3 B♭3 F♭4 A♭♭4 | 18 st, 248 mm | identical | none | | Drop 2 and 4 | B♭2 F♭3 D♭4 A♭♭4 | 21 st, 289 mm | identical | none | | Shell, root ♭♭7 ♭3 | B♭2 A♭♭3 D♭4 | 15 st, 206 mm | subset | omits F♭ | | Guide tones, ♭3 and ♭♭7 | D♭4 A♭♭4 | 6 st, 83 mm | subset | omits B♭ and F♭ | | Rootless close | D♭4 F♭4 A♭♭4 | 6 st, 83 mm | subset | omits B♭ | ## One-edit neighbors | Becomes | Edit | Changes | Common tones | | --- | --- | --- | --- | | B♭dim | 1 ♭3 ♭5 | drops A♭♭ | 3 | | B♭m7♭5 | 1 ♭3 ♭5 ♭7 | A♭♭ becomes A♭ | 3 | | B♭m6 | 1 ♭3 5 6 | F♭ becomes F | 3 | | B♭m | 1 ♭3 5 | F♭, A♭♭ becomes F | 2 | | B♭m7 | 1 ♭3 5 ♭7 | F♭, A♭♭ becomes F, A♭ | 2 | | B♭mMaj7 | 1 ♭3 5 7 | F♭, A♭♭ becomes F, A | 2 | | B♭6 | 1 3 5 6 | D♭, F♭ becomes D, F | 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 | | --- | --- | --- | | B♭3 | 58 | 233.08 Hz | | D♭4 | 61 | 277.18 Hz | | F♭4 | 64 | 329.63 Hz | | A♭♭4 | 67 | 392.00 Hz | ## Questions and answers ### What notes are in B♭dim7? B♭dim7 contains B♭, D♭, F♭ and A♭♭. The formula is 1, ♭3, ♭5, ♭♭7. ### How do you play B♭dim7 on piano? Play B♭, D♭, F♭ and A♭♭ together. Right hand fingers 2, 3, 4, 5; left hand 5, 4, 3, 2. B♭ and D♭ are black keys; F♭ and A♭♭ are white. ### What are the inversions of B♭dim7? 4 positions: root position B♭ D♭ F♭ A♭♭, B♭dim7/D♭, B♭dim7/F♭, B♭dim7/A♭♭. ### What is the difference between B♭dim7 and B♭dim? Drops A♭♭. 3 of the notes are shared. ### What is an easy B♭dim7 for small hands? The guide tones, ♭3 and ♭♭7 voicing, D♭4 A♭♭4, spans 6 semitones or about 83 mm. ### What are the frequencies of B♭dim7? From B♭3 at A440 in 12-TET: 233.08, 277.18, 329.63, 392.00 Hz. ### What is the set class of B♭dim7? Prime form (0369), Forte 4-28, interval vector <004002>. ### How do I transpose B♭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 A♯dim7 the same as B♭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:b-flat Last reviewed: 2026-08-12