The A♯ Major 13th chord (A♯maj13) contains the notes A♯, C♯♯, E♯, G♯♯, B♯, D♯, and F♯♯. Its interval formula is R-M3-P5-M7-M9-P11-M13. A major 11th plus the 13th — maximally consonant extended chord, dense and shimmering.
=B♭ Major 13th›
This is the same chord as B♭ Major 13th — the same keys on the keyboard, spelled with flats.
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A♯maj13
The A♯ Major 13th chord is a seven-note chord made up of A♯, C♯♯, E♯, G♯♯, B♯, D♯, and F♯♯. It is built from a root, major third, perfect fifth, major seventh, major ninth, perfect eleventh, and major thirteenth.
Construction
A♯ Major 13th = Root + Major 3rd + Perfect 5th + Major 7th + Major 2nd + Perfect 4th + Major 6th = A♯ · C♯♯ · E♯ · G♯♯ · B♯ · D♯ · F♯♯
Note
Interval
Degree
A♯
Root
1
C♯♯
Major 3rd
3
E♯
Perfect 5th
5
G♯♯
Major 7th
7
B♯
Major 2nd
9
D♯
Perfect 4th
11
F♯♯
Major 6th
13
Key Signature
A chord has no key signature of its own, but the A♯ Major 13th is the tonic (I) chord of A# Major, whose key signature has 2 flats (B♭, E♭).
B♭E♭
Order of flats
Flats are added in a fixed order — the reverse of the sharp order. Each new flat key adds the next flat on the list.
B♭E♭A♭D♭G♭C♭F♭
Mnemonic:Battle Ends And Down Goes Charles’ Father
Chords in the Key of A♯ Major
These are the triads built on each degree of the A♯ major scale:
The notes A♯ – C♯♯ – E♯ – G♯♯ – B♯ – D♯ – F♯♯ aren’t exclusive to this chord. Depending on which note is the bass and how the chord functions, the same pitches also spell the following:
Keep going with the Major 13th chord — these pages cover the underlying theory, the connected reference material, and the practice tools that work with this chord.
The note names, intervals, fingering, and harmony on this chord page are grounded in the following sources. Public domain treatises and scores are linked to their full text; primary data is piano.org's own interval-derived reference dataset — continuously maintained and human-verified, with no fixed publication date.