Water Properties Calculator (Density, Viscosity, Surface Tension vs Temperature)
Density, dynamic and kinematic viscosity, surface tension and specific weight of liquid water between 0 and 100 °C — the numbers you need for a Reynolds number or a pump calculation.
Results
The dashed line marks the value you entered.
What this tool does
Water is densest at about 4 °C (999.97 kg/m³) and lighter on both sides, which is why ice floats and lakes freeze from the top. Its viscosity changes far more than its density: hot water is about six times less viscous than near-freezing water (1.79 mPa·s at 0 °C, 0.28 at 100 °C), so the same pipe at the same flow can be laminar cold and turbulent hot. At 20 °C it is almost exactly 1 mPa·s. Density comes from Kell's polynomial, viscosity from the Vogel equation (good to a few percent) and surface tension from the IAPWS correlation.
Formula
ρ = Kell (1975) polynomial · μ = 2.414×10⁻⁵ × 10^(247.8 ÷ (T − 140)) Pa·s (Vogel) · ν = μ ÷ ρ · σ = 235.8 τ^1.256 (1 − 0.625 τ) mN/m with τ = 1 − T ÷ 647.096 (IAPWS)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
t | Water temperature (0–100 °C) | °C |
DE | Density of water | kg/m³ |
MU | Dynamic viscosity | mPa·s |
NU | Kinematic viscosity | mm²/s |
ST | Surface tension against air | mN/m |
SW | Specific weight | kN/m³ |
Worked example
- Water temperature (0–100 °C)20 °C
- Density of water998.20 kg/m³
- Dynamic viscosity1.0017 mPa·s
- Kinematic viscosity1.0036 mm²/s
- Surface tension against air72.74 mN/m
- Specific weight9.789 kN/m³
Limitations
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- The default values are typical reference figures, not measurements of your situation. Replace them with your own data whenever you have it.