Viscosity of water: calculator and table by temperature
The viscosity of water drops sharply with temperature: at 20 °C it is about three times what it is at 90 °C. Enter a temperature and pressure to get the dynamic viscosity, the kinematic viscosity and the density.
Viscosity of water at atmospheric pressure
| T (°C) | μ (mPa·s) | ν (mm²/s) | ρ (kg/m³) |
|---|---|---|---|
| 0.01 | 1.7911 | 1.7914 | 999.84 |
| 5 | 1.5182 | 1.5182 | 999.97 |
| 10 | 1.3059 | 1.3063 | 999.70 |
| 15 | 1.1376 | 1.1386 | 999.10 |
| 20 | 1.0016 | 1.0034 | 998.21 |
| 25 | 0.8900 | 0.8927 | 997.05 |
| 30 | 0.7972 | 0.8007 | 995.65 |
| 35 | 0.7191 | 0.7234 | 994.04 |
| 40 | 0.6527 | 0.6578 | 992.22 |
| 45 | 0.5958 | 0.6017 | 990.22 |
| 50 | 0.5465 | 0.5531 | 988.05 |
| 60 | 0.4660 | 0.4740 | 983.21 |
| 70 | 0.4036 | 0.4127 | 977.78 |
| 80 | 0.3541 | 0.3643 | 971.80 |
| 90 | 0.3142 | 0.3255 | 965.32 |
| 99 | 0.2846 | 0.2967 | 959.07 |
ν = μ / ρ, 1 mPa·s = 1 cP, 1 mm²/s = 1 cSt
Dynamic or kinematic
Dynamic viscosity, μ, is a fluid’s resistance to shear, in Pa·s. Kinematic viscosity, ν, is the dynamic viscosity divided by the density, in m²/s, and it is the one in the Reynolds number Re = VD/ν. 1 mPa·s is one centipoise, and 1 mm²/s is one centistokes.
Example
Water at 20 °C and atmospheric pressure: μ = 1.0016 mPa·s, ν = 1.0034 mm²/s and ρ = 998.21 kg/m³. At 80 °C the dynamic viscosity falls to 0.3541 mPa·s, almost three times lower, which is why hot water flows through a pipe with smaller losses.
About the calculation
Viscosity comes from IAPWS R12-08 (2008), in the form the standard recommends for engineering use, with density from IAPWS-IF97. The code reproduces every verification value in Table 4 of the standard, to all published digits, and gives the ISO reference value at 20 °C.
At atmospheric pressure water boils at 99.97 °C, so at 100 °C the calculator returns the viscosity of steam. The code is open source on GitHub and npm as engineering-tables.