W/(m·K)
watt per meter-kelvin
Thermal conductivityexact by definition
The watt per metre-kelvin is the SI unit of thermal conductivity, the k in Fourier's law: the heat in watts crossing one square metre of a one-metre-thick slab per kelvin of temperature difference across it. As the coherent SI combination the factor of 1 is exact. Copper is about 400 W/(m·K), water 0.6, still air 0.026 and fibreglass insulation about 0.04.
Watch out: Conductivity is a material property and takes no thickness. Divide it by a thickness to get a conductance, or divide a thickness by it to get an R-value. Note also that thermal conductivity and electrical conductivity share the word and nothing else: this one is W/(m·K), the electrical one is S/m.
| 1 W/(m·K) | 1 W/(m·K) |
Solvers that use thermal conductivity