Scale degrees · B♭ major

The ♭3 of B♭ is D♭

The ♭3 (flat three, written b3) of B♭ (B flat, Bb) is D♭ (D flat): a minor third above the root.

How to find it

Count letters first, the root included: B, C, D. A 3rd lands on D.

Then the sound: a minor third is 3 semitones above B♭, and the D that is 3 semitones up is D♭.

That is why it is D♭ and not C♯: C♯ is the same key on the piano, but from B♭ it would be a 2nd, not a 3rd.

Where you meet it

The ♭3 makes a chord minor: B♭ minor is the root, D♭ and the 5th. Over a dominant chord the same key on the piano is usually written as the ♯9, with another letter.

In B♭ minor:

B♭ · D♭ · F

The ♭3 in every key

Key	The ♭3
C	E♭
G	B♭
D	F
A	C
E	G
B	D
F♯	A
D♭	F♭
A♭	C♭
E♭	G♭
B♭	D♭
F	A♭

Every degree of B♭