Chords in B major

B major is built from the notes B, C#, D#, E, F#, G# and A#. Its scale carries 5 sharps. Harmonising that scale in thirds gives seven chords — 3 majors, 3 minors and 1 diminished — starting on B as the I. The chord on the fifth degree is F#, a major V, so B major has the leading tone that makes a F#-to-B cadence sound final.

Beyond those seven, B major commonly borrows Bm (i), C#dim (iiø), D (bIII), Em (iv) and F#m (v) from the parallel minor — the mixture chords that give a progression somewhere unexpected to go.