# Poise

The poise (symbol P, /ˈpɔɪz/) is the unit of dynamic viscosity in the centimetre–gram–second system of units.[1] It is named after Jean Léonard Marie Poiseuille.

${\displaystyle 1~{\text{P}}=0.100~{\text{kg}}\cdot {\text{m}}^{-1}\cdot {\text{s}}^{-1}=1~{\text{g}}\cdot {\text{cm}}^{-1}\cdot {\text{s}}^{-1}.}$

The analogous unit in the International System of Units is the pascal-second (Pa·s):

${\displaystyle 1~{\text{Pa}}\cdot {\text{s}}=1~{\text{kg}}\cdot {\text{m}}^{-1}\cdot {\text{s}}^{-1}=10~{\text{P}}.}$

The poise is often used with the metric prefix centi- because the viscosity of water at 20 °C is almost exactly 1 centipoise. A centipoise is one hundredth of a poise, equal to one millipascal-second (mPa·s) in SI units (1 cP = 10−3 Pa·s = 1 mPa·s).

The centipoise is properly abbreviated cP, but the alternative abbreviations cps, cp, and cPs are also commonly seen.

Water has a viscosity of 0.00899 poises at 25 °C and a pressure of 1 atmosphere (0.00899 P = 0.899cP = 0.899 mPa·s).[2]