Physics > Viscosity of Liquids
Viscosity is a measure of the resistance of a fluid to being deformed by either shear stress or extensional stress. It is commonly thought of as 'thickness', or resistance to flow. It describes a fluid's internal resistance to flow and may be thought of as a measure of fluid friction. In simple terms, water is 'thin', having a lower viscosity, while cooking oil is 'thick' having a higher viscosity.
The SI physical unit of dynamic viscosity is the pascal-second (Pa·s).
The cgs physical unit for dynamic viscosity is the poise (P), named after Jean Louis Marie Poiseuille. It is more commonly expressed as centipoise (cP). The centipoise is commonly used because water has a viscosity of 1.0020 cP (at 20 °C).
| Liquid |
Dynamic Viscosity (Pa·s) |
Viscosity (cP) |
| Acetone |
3.06 × 10−4 |
0.306 |
| Methanol |
5.44 × 10−4 |
0.544 |
| Benzene |
6.04 × 10−4 |
0.604 |
| Water |
8.94 × 10−4 |
0.894 |
| Ethanol |
1.074 × 10−3 |
1.074 |
| Mercury |
1.526 × 10−3 |
1.526 |
| Nitrobenzene |
1.863 × 10−3 |
1.863 |
| Propanol |
1.945 × 10−3 |
1.945 |
| Ethylene Glycol |
1.61 × 10−2 |
16.1 |
| Sulfuric Acid |
2.42 × 10−2 |
24.2 |
| Olive Oil |
0.081 |
81 |
| Glycerol |
0.934 |
934 |
| Castor Oil |
0.985 |
985 |
| Corn Syrup |
1.3806 |
1380.6 |