μL⁻¹

per microliter

Number densityexact by definition

The per microlitre is exactly 10⁹ m⁻³, the unit of every blood count. Red cells run 4 to 6 million per μL, white cells 4000 to 11000, and platelets 150000 to 400000.

1 μL⁻¹ 1,000,000,000 m⁻³