mL⁻¹
per milliliter
Number densityexact by definition
The per millilitre is exactly 10⁶ m⁻³, the same value as per cubic centimetre and the label microbiology and cell culture actually use. A confluent mammalian culture is around 10⁶ cells/mL, and drinking water plate counts are reported as CFU/mL.
Watch out: Colony forming units per millilitre are not cells per millilitre. A CFU is whatever grew into one colony, which may have been a clump of a hundred cells or a single one that happened to be culturable, and most environmental bacteria never grow on a plate at all.
| 1 mL⁻¹ | 1,000,000 m⁻³ |