Thermal Conductivity Converter
Convert between thermal conductivity units — W/(m·K), BTU/(h·ft·°F), W/(cm·K), and more — instantly. Real-time conversion with copy-to-clipboard.
Thermal Conductivity Converter
Enter a value in any unit — see the conversion in all others instantly.
How to Use the Thermal Conductivity Converter
An insulation datasheet lists the thermal conductivity as 0.034 BTU per hour per foot per degree Fahrenheit. Your building energy model requires the value in watts per metre per kelvin. The numbers are in completely different unit systems and the conversion is not intuitive. Enter the value, pick the source unit, and the converter shows the equivalent in all five supported thermal conductivity units.
A spray-foam manufacturer lists conductivity as 0.025 BTU per hour per foot per degree F. Enter 0.025 in BTU per hour per foot per degree F and the converter shows 0.0433 W per metre per kelvin. This value is well below the 0.1 threshold that classifies an insulator, confirming the material is suitable for wall cavity insulation.
A thermal interface material spec sheet shows 8 W per centimetre per kelvin. Convert to W per metre per kelvin and the result is 800 — still well above 10, confirming it is a thermal conductor. The converter also shows 462 BTU per hour per foot per degree F for US engineering documentation.
A 1960s chemistry paper reports thermal conductivity as 0.001 calorie per second per centimetre per degree C. Enter 0.001 in cal per s per cm per degree C and the converter shows 0.4184 W per metre per kelvin — a value typical of a poor conductor like glass. The calorie-based unit is rarely used in modern papers but still appears in older literature.
A heat exchanger design requires a material with conductivity above 50 W per metre per kelvin. Copper at 401 W per metre per kelvin and aluminium at 237 both qualify. Enter 401 in W per metre per kelvin and the converter shows 231.8 BTU per hour per foot per degree F, which you can cite in the American engineering specification document.
How the Thermal Conductivity Converter Works
Every conversion normalises the input to W per metre per kelvin, then converts to the target unit using fixed ratios. The tool runs entirely in your browser with no server calls.
Thermal Conductivity Units
The five supported units cover SI, imperial, centimetre-gram-second, and calorie-based systems. W per metre per kelvin is the SI standard used in most scientific and engineering contexts. BTU per hour per foot per degree F is the imperial equivalent used in US building and mechanical engineering. W per centimetre per kelvin scales the SI unit by centimetres, common in materials science. calorie per second per centimetre per degree C uses calories and centimetres, still found in older chemistry literature. kilowatt per metre per kelvin is used for very high conductivity materials like metals.
Conversion Factor Mathematics
Each unit maps to a fixed factor relative to W per metre per kelvin. The converter multiplies your input by the source factor to get the SI base value, then divides by the target factor to produce the result. For example, 1 BTU per hour per foot per degree F equals 0.577789 W per metre per kelvin, so converting BTU to W per metre per kelvin means multiplying by that factor. The formula is Result = Input x (FromFactor / ToFactor).
Material Classification
Materials with thermal conductivity above roughly 10 W per metre per kelvin, like copper at 401 or aluminium at 237, are classified as thermal conductors. Materials below 0.1 W per metre per kelvin, like styrofoam at 0.03 or aerogel at 0.001, are classified as thermal insulators. This converter helps you quickly compare values across unit systems used in different engineering disciplines.
Frequently Asked Questions
What is a typical thermal conductivity value for copper?
Copper has a thermal conductivity of approximately 401 W per metre per kelvin, making it one of the best metallic conductors of heat. This high value is why copper is widely used in heat exchangers, cookware, and electrical wiring where efficient heat transfer is required. For comparison, aluminium at 237 W per metre per kelvin is about 40 percent less conductive than copper.
How does thermal conductivity differ from thermal diffusivity?
Thermal conductivity measures how much heat a material can conduct, while thermal diffusivity measures how quickly it changes temperature. A material with high conductivity but also high heat capacity may have moderate diffusivity. Both properties are important but answer different engineering questions about steady-state heat flow versus transient temperature response.
Why do metals conduct heat better than non-metals?
Metals have free electrons that move easily through the crystal lattice, carrying kinetic energy as heat. This electron mobility allows metals like silver, copper, and aluminium to transfer heat far more efficiently than non-metals, which rely on slower atomic vibrations called phonons to conduct heat. The difference is dramatic: silver at 429 W per metre per kelvin conducts roughly 4,000 times better than wood at about 0.1 W per metre per kelvin.
What is the thermal conductivity of styrofoam?
Styrofoam typically has a thermal conductivity of about 0.03 W per metre per kelvin, which makes it an excellent insulator. This low value is due to the trapped air pockets within the foam structure, which resist heat flow and are why styrofoam is commonly used in packaging and building insulation. For context, this is roughly 13,000 times less conductive than copper.
How do I convert BTU per hour per foot per degree F to W per metre per kelvin?
Multiply the BTU per hour per foot per degree F value by 0.577789 to get the equivalent in W per metre per kelvin. For example, a material with a conductivity of 1 BTU per hour per foot per degree F equals approximately 0.578 W per metre per kelvin. This converter does the math automatically for all supported unit pairs so you do not need to remember the conversion factors.
Which material has the highest known thermal conductivity?
Diamond has the highest thermal conductivity of any known material at roughly 2,000 W per metre per kelvin, far exceeding silver at 429. At the opposite end, aerogels and vacuum insulation panels can have values as low as 0.001 W per metre per kelvin, making them among the best insulators available. This extreme range of over six orders of magnitude illustrates why choosing the right unit and material matters in thermal design.