Water Viscosity Calculator — Dynamic & Kinematic Viscosity vs Temperature
Find the dynamic viscosity (μ, in cP / mPa·s) and kinematic viscosity (ν, in cSt) of liquid water at any temperature from 0 °C to 370 °C, using the Vogel–Tammann–Fulcher empirical equation, with a viscosity-vs-temperature curve.
°C
Resistance to shear flow — decreases sharply as temperature rises
- 1
Temperature in K
20 + 273.15 = 293.15 - 2
VTF exponent (B ÷ (T − C))
247.8 ÷ (293.15 − 140) = 1.618 - 3
Dynamic viscosity (Pa·s)
2.414×10⁻⁵ × 10^1.618 = 0.001002Vogel–Tammann–Fulcher equation with constants calibrated for water. - 4
Dynamic viscosity (mPa·s = cP)
0.001002 × 1000 = 1.0017
How does this calculator work?
Water viscosity falls from ~1.79 cP at 0 °C to ~1.00 cP at 20 °C and ~0.28 cP at 100 °C. The Vogel equation μ = 2.414 × 10⁻⁵ × 10^(247.8/(T−140)) (T in kelvin, result in Pa·s) fits IAPWS data to < 1% over 0–370 °C. Kinematic viscosity ν = μ/ρ ≈ 1 cSt at 20 °C.
Formula
How this is calculated
The dynamic viscosity of water (μ) measures its resistance to shear flow: the higher the viscosity, the more force is needed to move one fluid layer past another. It is measured in pascal-seconds (Pa·s) or equivalently millipascal-seconds (mPa·s), which equal the older unit centipoise (cP). At 20 °C water has μ ≈ 1.002 cP; at 100 °C only 0.282 cP — viscosity falls steeply because heat disrupts the hydrogen-bond network linking water molecules.
This calculator applies the Vogel–Tammann–Fulcher (VTF) equation μ = A × 10^(B/(T − C)), with constants A = 2.414 × 10⁻⁵ Pa·s, B = 247.8 K, and C = 140 K. These constants are calibrated for liquid water and reproduce IAPWS-IF97 reference data to within 1% over the range 0–370 °C. Below 100 °C water is liquid at atmospheric pressure; above 100 °C the formula applies to superheated or pressurised liquid water (common in industrial heat-transfer equipment).
Kinematic viscosity ν = μ/ρ factors in density ρ and is expressed in mm²/s (centistokes, cSt). It appears in the Reynolds number and pipe-friction correlations. Water density is computed from a standard IAPWS-95 polynomial fit valid for 0–100 °C; a linear approximation is used above 100 °C.
Frequently asked questions
At 20 °C water has a dynamic viscosity of approximately 1.002 mPa·s (cP) and a kinematic viscosity of about 1.004 cSt (mm²/s). At 25 °C it drops to about 0.890 cP and 0.893 cSt. These are the benchmark values most commonly cited in engineering and chemistry tables.
In liquids, viscosity is dominated by intermolecular forces rather than molecular collisions (unlike gases). As temperature rises, thermal energy weakens the hydrogen bonds holding water molecules together, reducing internal friction and allowing layers to flow more freely. This is the opposite of gases, where viscosity increases with temperature.
Dynamic viscosity (μ, in Pa·s or cP) is the direct measure of fluid resistance to shear — force per area per velocity gradient. Kinematic viscosity (ν = μ/ρ, in m²/s or cSt) normalises by density and describes how quickly momentum diffuses through the fluid. Pipe-flow and Reynolds-number calculations use kinematic viscosity.
Also known as
TG we-Calculate Editorial Team. (2026). Water Viscosity Calculator — Dynamic & Kinematic Viscosity vs Temperature [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/water-viscosity-calculator
TG we-Calculate Editorial Team. "Water Viscosity Calculator — Dynamic & Kinematic Viscosity vs Temperature." TG we-Calculate. 2026. https://we-calculate.com/calculator/water-viscosity-calculator.
TG we-Calculate Editorial Team, "Water Viscosity Calculator — Dynamic & Kinematic Viscosity vs Temperature," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/water-viscosity-calculator
@misc{wecalculate_water_viscosity_calculator, title = {Water Viscosity Calculator — Dynamic & Kinematic Viscosity vs Temperature}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/water-viscosity-calculator}}, year = {2026}, note = {TG we-Calculate} }
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