Water Viscosity and Density vs Temperature Calculator

Estimate pure liquid-water density, dynamic viscosity, and kinematic viscosity from temperature at approximately atmospheric pressure.

Engineering screening tool—verify inputs and results independently. Use at your own risk.

Water condition

Dynamic viscosity, μ

—mPa·s

Enter a valid temperature to calculate.

Density, ρ— kg/m³

Kinematic viscosity, ν— mm²/s

Normalized temperature—

Pressure basis≈ 1 atm

Properties across temperature

Dynamic viscosityDensity

How to use

Select the temperature unit: degrees Celsius, degrees Fahrenheit, or kelvin.
Enter the bulk liquid-water temperature in the displayed unit. The accepted range is equivalent to 0–100 °C.
Select Calculate; results also update when the value or unit changes. Select Reset to restore the 25 °C example.
Read dynamic viscosity as the primary result, then density and kinematic viscosity as supporting properties. The chart marker shows the same state on both curves.
Correct any red warning before interpretation. Values outside the bounded liquid range are not extrapolated.
Do not use this model for steam, ice, boiling under altered pressure, saline or contaminated water, high-pressure work, or safety-critical property certification.

Equations used

T = (T_°F − 32)5/9 or T = T_K − 273.15, in °C.

μ = 1.790 exp{[(−1230 − T)T]/(36100 + 360T)} mPa·s.

ρ = 1000[1 − |(T − 4)/622|^1.7] kg/m³.

ν = 1000μ/ρ mm²/s.

Definitions and sign conventions: T is bulk water temperature; μ is positive dynamic viscosity; ρ is positive mass density; and ν is positive kinematic viscosity. Increasing T is the positive temperature direction. The factor 1000 converts mPa·s and kg/m³ to mm²/s.

Worked example

Choose °C and enter 25.
Select Calculate.
Expected output is approximately 0.8927 mPa·s dynamic viscosity, 996.85 kg/m³ density, and 0.8956 mm²/s kinematic viscosity.
Interpretation: at room temperature, one millipascal-second is a useful order-of-magnitude estimate, but the plotted decline shows why temperature must be controlled in flow and lubrication calculations.

Theory and method

The calculator treats water as a pure, homogeneous, single-phase Newtonian liquid in thermal equilibrium. The exponential expression gives dynamic viscosity directly from temperature. The density relation captures the density maximum near 4 °C and its decline toward boiling. Kinematic viscosity is derived from their ratio, so all three outputs remain internally consistent.

Assumptions and limits

Temperature is 0–100 °C inclusive and pressure is approximately atmospheric.
Pressure dependence, salinity, dissolved gas, suspended solids, confinement, and phase change are omitted.
The equations are screening correlations, not a replacement for IAPWS state-property software or calibrated measurements.

References

N.-S. Cheng (2008), “Formula for the Viscosity of a Glycerol–Water Mixture,” Industrial & Engineering Chemistry Research 47(9), 3285–3288, doi:10.1021/ie071349z. Independent comparison basis: IAPWS Formulation 2008 for the Viscosity of Ordinary Water Substance.

Use these properties as inputs to a fluid or lubrication model, rather than assuming room-temperature water values.