Scale degrees · A major

The ♭13 of A is F

The ♭13 (flat thirteen, written b13) of A is F: a minor thirteenth above the root.

A — the root, 1F — the ♭13

How to find it

A 13th is a 6th an octave up, so it takes the 6th's letter: A, B, C, D, E, F.

Then the sound: a minor thirteenth is 20 semitones above A, which is exactly where F is — no sharp or flat needed.

Where you meet it

The ♭13 is an altered tension of the dominant chord, one of the notes of the altered scale.

In A7♭13:

A · C♯ · E · G · F

The ♭13 in every key

KeyThe ♭13
CA♭
GE♭
DB♭
AF
EC
BG
F♯D
D♭B𝄫
A♭F♭
E♭C♭
B♭G♭
FD♭

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