B-flat major

B♭ major or B-flat major is a major scale starting on B-flat. Its key signature has two flats. It has the pitches of B♭, C, D, E♭, F, G, A, and B♭.

B♭ major

Relative key	G minor
Parallel key	B♭ minor
Dominant key
Subdominant
Notes in this scale
B♭, C, D, E♭, F, G, A, B♭

Its relative minor is G minor, and its parallel minor is B♭ minor.

B-flat major is the home key of many wind instruments, such as clarinets, trumpets, saxophones, and flutes in B-flat. This means they can be played the most easily in this key. Because of this, many works for concert bands (those you might have played in while you were at school) are written in this key or a closely related one such as F major or E-flat major.

Haydn's Symphony No. 98, which had both trumpet and timpani, is known as the first symphony that anyone had written in that key. Actually, his brother Michael Haydn had written one earlier. However, Joseph Haydn still gets credit for writing the timpani part at actual pitch with an F major key signature (instead of transposing with a C major key signature), something that made things easier and made more sense.^[1]

Five of Mozart's piano concerti are in B-flat major.