Thermal Conductivity of Water

k_{w} = 0.598\ \text{W/(m}{\cdot}\text{K)}

Value	598 mW/(m·K) (0.598 W/(m·K)) Use in the calculator →
Status	Measured: ± 3 mW/(m·K) (0.5 % relative)
Source	IAPWS R15-11(2011), Release on the IAPWS Formulation 2011 for the Thermal Conductivity of Ordinary Water Substance, evaluated at 293.15 K and 0.101325 MPa: 0.5980 W/(m·K)
Categories	Material Properties Engineering & Trade

Thermal Conductivity of Water in every thermal conductivity unit

Unit	Value
milliwatt per meter-kelvin	598 mW/(m·K)
BTU inch per hour square foot Fahrenheit	4.1462161 BTU·in/(h·ft²·°F)
watt per meter-kelvin	0.598 W/(m·K)
BTU per hour-foot-Fahrenheit	0.34551801 BTU/(h·ft·°F)
watt per meter-Celsius	0.598 W/(m·°C)
kilocalorie per hour meter Celsius	0.51453155 kcal/(h·m·°C)
watt per centimeter-kelvin	0.00598 W/(cm·K)
calorie per second centimeter Celsius	0.0014292543 cal/(s·cm·°C)
kilowatt per meter-kelvin	0.000598 kW/(m·K)

This value moves with temperature

Water at any temperature

0 to 100 °CThe value above is one point on this curve. Liquid water from 0 to 100 °C at 1 atm — density, viscosity, specific heat, thermal conductivity and vapour pressure, all at the same state.

Learning zone

Water conducts heat better than most liquids (roughly four times better than mineral oil and 25 times better than air) thanks to hydrogen bonding, and unusually it improves as it warms, peaking near 0.68 W/(m·K) at about 130 °C before declining. It is one of the terms in the Prandtl number and therefore in every convective correlation for water-side film coefficients.

The distinction that trips people up is conduction versus convection. Still water is a mediocre insulator, but water moving through a tube transfers heat by convection at film coefficients of thousands of W/(m²·K): the conductivity only enters through the correlation. Adding glycol makes this worse twice over: a 50 % propylene-glycol mix has conductivity near 0.40 W/(m·K) and roughly triple the viscosity at low temperature, which is why glycol loops need larger pumps and more heat-transfer surface for the same duty.

Used by 2 solvers

Heat Conduction Rate

P = \tfrac{k A \Delta T}{d}

Reynolds Number

Re = \frac{\rho v D}{\mu}

Revised 1 November 2026

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formula.expert. (2026, November 1). Thermal Conductivity of Water. https://formula.expert/constants/thermal-conductivity-water