Viscosity Definitions

Absolute viscosity:

the ratio of the shear stress in a fluid to the rate of shearing strain.

Unit of absolute viscosity in the metric system:

poise and centipoise:

1 poise = 1 gram / (cm) (sec) and

1 centipoise = 1 / 100 poise

Unit of absolute viscosity in the imperial system:

slug / (ft) (sec):

1 slug / (ft) (sec) = 1 / 0.002089 poise

Kinematic viscosity:

the absolute viscosity divided by density.

Unit of kinematic viscosity: in the metric system and commonly used in the countries using the imperial system:

stoke and centistoke:

1 stoke = 1 poise / density (gm / mL)

1 centistoke = 1 / 100 stoke

Other units of kinematic viscosity: in the imperial system, the most practical unit for making calculations is ft² / sec:

1 ft² / sec = 92,903 centistoke and

1 centistoke = 1.076 x 10-5 ft² / sec