Thermal Conductivity Converter
Convert between W/(m·K), kW/(m·K), BTU/(ft·h·°F), and cal/(cm·s·°C) instantly.
Type in any field and the others update automatically.
Type in any field — the others update instantly.
Thermal conductivity measures how quickly heat moves through a material. The SI unit is the watt per meter-kelvin, W/(m·K). A high number means heat races through (metals); a low number means the material holds heat back (insulators). The gap between the two is enormous.
Key conversions:
- 1 kW/(m·K) = 1,000 W/(m·K)
- 1 BTU/(ft·h·°F) = 1.7307 W/(m·K)
- 1 cal/(cm·s·°C) = 418.68 W/(m·K)
Where common materials sit:
- Copper: about 385 W/(m·K)
- Aluminum: about 205 W/(m·K)
- Steel: about 50 W/(m·K)
- Water: about 0.6 W/(m·K)
- Still air: about 0.026 W/(m·K)
Copper conducts heat roughly 15,000 times better than still air, which explains a lot of everyday design. Pots and heat sinks are aluminum or copper; insulation works by trapping air inside foam or fiber so it can’t circulate and ferry heat away.
The BTU per foot-hour-Fahrenheit unit is the one to watch, since US building and HVAC work still runs on it. Comparing an American insulation spec against a metric one without converting is asking for a mistake. And remember insulation is normally rated by R-value (resistance), which is thickness divided by conductivity, not conductivity itself. A thick layer of a mediocre insulator can easily beat a thin layer of a good one.
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This converter runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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