Chords in the key of B flat major
The chart below lists the common chords in the key 
of B flat major. The first row are triads and four 
note voicings in the second row. Roman numerals 
indicate each chords position relative to the scale.

B flat major scale notes: Bb C D Eb F G A
Major key chord sequence: Maj min min Maj Maj min dim
Note: The same chords and scale notes are used for the 
key of A sharp major but this key isn't used often 
because of notation difficulties caused by the need 
for a double sharp.

I	ii	iii	IV	V	vi	vii
Bbmaj	Cmin	Dmin	Ebmaj	Fmaj	Gmin	Adim
Bbmaj7	Cmin7	Dmin7	Ebmaj7	F7	Gmin7	Am7b5
Common chord progressions in B flat major
I - IV - V	Bb - Eb - F
I - vi - IV - V	Bb - Gm - Eb - F
ii - V - I	Cm7 - F7 - Bbmaj7