Viscosity is measured with various types of viscometer, typically at 25°C (standard state).


Dynamic viscosity

The SI physical unit of dynamic viscosity if the Pascal-second (Pa·s), which is identical to 1 N·s/m2 or 1 kg/m·s).

In France there have been some attempts to establish the poiseuille (Pl) as a name for the Pa·s but without international success.

Care must be taken in not confusing the poiseuille with the poise!

The cgs physical unit for dynamic viscosity is the poise (P) named for Jean Louis Marie Poiseuille.

It is more commonly expressed, particularly in ASTM standards, as centipoise (cP).

1 poise = 100 centipoise = 1 g/cm·s = 0.1 Pa·s.

Kinematic viscosity

The SI physical unit of kinematic viscosity is the (m2/s).

The cgs physical unit for kinematic viscosity is the stokes (abbreviated S or St), named for George Gabriel Stokes .

It is sometimes expressed in terms of centistokes (cS). US usage is the stoke.

1 stokes = 100 centistokes = 1 cm2/s = 0.0001 m2/s.