| poise | |
|---|---|
| Unit system | Centimetre–gram–second system of units |
| Unit of | Dynamic viscosity |
| Symbol | P |
| Named after | Jean Léonard Marie Poiseuille |
| Derivation | 1 P = 1 dyn⋅s/cm2 |
| Conversions | |
| 1 Pin ... | ... is equal to ... |
| CGS base units | 1 cm−1⋅g⋅s−1 |
| SI units | 0.1 Pa⋅s |
The poise (symbol P; /pɔɪz, pwɑːz/) is the unit of dynamic viscosity (absolute viscosity) in the centimetre–gram–second system of units (CGS).[1] It is named after Jean Léonard Marie Poiseuille (see Hagen–Poiseuille equation). The centipoise (1 cP = 0.01 P) is more commonly used than the poise itself.
Dynamic viscosity has dimensions of 
![{\displaystyle [{\mathsf {M}}^{1}{\mathsf {L}}^{-1}{\mathsf {T}}^{-1}]}](https://wikimedia.org/api/rest_v1/media/math/render/svg/e4e00a7e8b4e08a7fb7e609f10ea7f577adf8feb)
The analogous unit in the International System of Units is the pascal-second (Pa⋅s):[2]
The poise is often used with the metric prefix centi- because the viscosity of water at 20 °C (standard conditions for temperature and pressure) is almost exactly 1 centipoise.[3] A centipoise is one hundredth of a poise, or one millipascal-second (mPa⋅s) in SI units (1 cP = 10−3 Pa⋅s = 1 mPa⋅s).[4]
The CGS symbol for the centipoise is cP. The abbreviations cps, cp, and cPs are sometimes seen.
Liquid water has a viscosity of 0.00890 P at 25 °C at a pressure of 1 atmosphere (0.00890 P = 0.890 cP = 0.890 mPa⋅s).[5]
