# 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.

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

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

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

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 one-hundredth of a poise, and 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 0.000899 poise at 25 °C and a pressure of 1 atmosphere. (0.000899 P = 0.899cP = 0.899 mPa·s) [2]