# A♭ Dominant 9th piano chord (A♭9) A♭9 contains A♭, C, E♭, G♭ and B♭. A dominant seventh with the ninth added on top. A♭, E♭, G♭ and B♭ are black keys; C is white. - Canonical page: https://piano.org/chords/dominant-9th/a-flat/ - Entity: chord:dominant-9th:a-flat - Notes: A♭ C E♭ G♭ B♭ - Formula: 1 3 5 ♭7 9 - Intervals from root: P1, M3, P5, m7, M9 - Interval stack (semitones): 4 3 3 4 - Also written: A♭9, Ab9, A♭ dominant 9th - 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 | Major third | 4 | | 5 | E♭ | Perfect fifth | 7 | | ♭7 | G♭ | Minor seventh | 10 | | 9 | B♭ | Major ninth | 14 | ## Fingering Rest your right hand over the notes with finger 1 on A♭, finger 2 on C, finger 3 on E♭, finger 4 on G♭, finger 5 on B♭. The left hand mirrors it. Right hand 1-2-3-4-5, left hand 5-4-3-2-1. Source: piano.org fingering method v1. ## Inversions | Position | Bass | Notes in order | Figured bass | Span | | --- | --- | --- | --- | --- | | Root position | A♭ | A♭3 C4 E♭4 G♭4 B♭4 | 9 | 14 st, 193 mm | | First inversion (A♭9/C) | C | C4 E♭4 G♭4 A♭4 B♭4 | 7/6/5 | 10 st, 138 mm | | Second inversion (A♭9/E♭) | E♭ | E♭4 G♭4 A♭4 B♭4 C5 | 7/4/3 | 9 st, 124 mm | | Third inversion (A♭9/G♭) | G♭ | G♭4 A♭4 B♭4 C5 E♭5 | 7/4/2 | 9 st, 124 mm | | Fourth inversion (A♭9/B♭) | B♭ | B♭3 C4 E♭4 G♭4 A♭4 | 9/7/5 | 10 st, 138 mm | ## Voicings (11) | Voicing | Notes | Span | Relation | Omits or adds | | --- | --- | --- | --- | --- | | Close, root position | A♭3 C4 E♭4 G♭4 B♭4 | 14 st, 193 mm | identical | none | | Close, first inversion | C4 E♭4 G♭4 A♭4 B♭4 | 10 st, 138 mm | identical | none | | Close, second inversion | E♭4 G♭4 A♭4 B♭4 C5 | 9 st, 124 mm | identical | none | | Close, third inversion | G♭4 A♭4 B♭4 C5 E♭5 | 9 st, 124 mm | identical | none | | Close, fourth inversion | B♭3 C4 E♭4 G♭4 A♭4 | 10 st, 138 mm | identical | none | | Drop 2 | G♭3 A♭3 C4 E♭4 B♭4 | 16 st, 220 mm | identical | none | | Drop 3 | E♭3 A♭3 C4 G♭4 B♭4 | 19 st, 261 mm | identical | none | | Drop 2 and 4 | C3 G♭3 A♭3 E♭4 B♭4 | 22 st, 303 mm | identical | none | | Shell, root 9 3 | A♭2 B♭3 C4 | 16 st, 220 mm | subset | omits E♭ | | Guide tones, 3 and 9 | C4 B♭4 | 10 st, 138 mm | subset | omits A♭ and E♭ | | Rootless close | C4 E♭4 G♭4 B♭4 | 10 st, 138 mm | subset | omits A♭ | ## One-edit neighbors | Becomes | Edit | Changes | Common tones | | --- | --- | --- | --- | | A♭7 | 1 3 5 ♭7 | drops B♭ | 4 | | A♭add9 | 1 3 5 9 | drops G♭ | 4 | | A♭maj9 | 1 3 5 7 9 | G♭ becomes G | 4 | | A♭m9 | 1 ♭3 5 ♭7 9 | C becomes C♭ | 4 | | A♭maj7 | 1 3 5 7 | G♭, B♭ becomes G | 3 | | A♭m7 | 1 ♭3 5 ♭7 | C, B♭ becomes C♭ | 3 | | A♭aug7 | 1 3 ♯5 ♭7 | E♭, B♭ becomes E | 3 | | A♭7sus4 | 1 4 5 ♭7 | C, B♭ becomes D♭ | 3 | | A♭6 | 1 3 5 6 | G♭, B♭ becomes F | 3 | ## Set theory - Absolute pitch classes: {8, 0, 3, 6, 10} - Relative pitch classes: [0, 4, 7, 10, 2] - Normal order: [6, 8, 10, 0, 3] - Prime form: (02469) - Forte number: 5-34 - Interval vector: <032221> ## Frequencies (close root position) | Note | MIDI | Frequency | | --- | --- | --- | | A♭3 | 56 | 207.65 Hz | | C4 | 60 | 261.63 Hz | | E♭4 | 63 | 311.13 Hz | | G♭4 | 66 | 369.99 Hz | | B♭4 | 70 | 466.16 Hz | ## Questions and answers ### What notes are in A♭9? A♭9 contains A♭, C, E♭, G♭ and B♭. The formula is 1, 3, 5, ♭7, 9. ### How do you play A♭9 on piano? Play A♭, C, E♭, G♭ and B♭ together. Right hand fingers 1, 2, 3, 4, 5; left hand 5, 4, 3, 2, 1. A♭, E♭, G♭ and B♭ are black keys; C is white. ### What are the inversions of A♭9? 5 positions: root position A♭ C E♭ G♭ B♭, A♭9/C, A♭9/E♭, A♭9/G♭, A♭9/B♭. ### What is the difference between A♭9 and A♭7? Drops B♭. 4 of the notes are shared. ### What is an easy A♭9 for small hands? The close, second inversion voicing, E♭4 G♭4 A♭4 B♭4 C5, spans 9 semitones or about 124 mm. ### What are the frequencies of A♭9? From A♭3 at A440 in 12-TET: 207.65, 261.63, 311.13, 369.99, 466.16 Hz. ### What is the set class of A♭9? Prime form (02469), Forte 5-34, interval vector <032221>. ### How do I transpose A♭9 to another key? Keep the 1, 3, 5, ♭7, 9 formula on the new root. C9 is C, E, G, B♭, D; C♯9 is C♯, E♯, G♯, B, D♯. ### Is G♯9 the same as A♭9? 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:dominant-9th:a-flat Last reviewed: 2026-08-12