Thermal Conductivity Converter

Convert thermal conductivity values among common SI, metric and customary units. Thermal conductivity indicates how readily a material conducts heat. SI uses W/(m·K).

ValueEnter zero or a positive value; scientific notation is accepted.Convert fromWatt per meter kelvin (W/(m·K))Milliwatt per meter kelvin (mW/(m·K))Watt per centimeter kelvin (W/(cm·K))Kilocalorie per hour meter degree Celsius (kcal/(h·m·°C))Btu per hour foot degree Fahrenheit (Btu/(h·ft·°F))Convert toWatt per meter kelvin (W/(m·K))Milliwatt per meter kelvin (mW/(m·K))Watt per centimeter kelvin (W/(cm·K))Kilocalorie per hour meter degree Celsius (kcal/(h·m·°C))Btu per hour foot degree Fahrenheit (Btu/(h·ft·°F))

Convert

Converted value0.5777893165 Btu/(h·ft·°F)

SI-base value1 W/(m·K)

Multiply by0.5777893165

The displayed results apply to the default example. Enable JavaScript to convert other values.

How to use this converter

1. Enter the thermal conductivity value.
2. Select its current unit and the unit you want.
3. Select Convert. The page shows the converted value, the SI-base value and the direct multiplication factor.

Conversion formula

Converted value = entered value × source-to-SI factor ÷ target-to-SI factor.

Every option is represented by its factor to watt per meter kelvin (W/(m·K)). This one-base method keeps reciprocal conversions consistent. Calculations run in your browser, and old results are hidden when an input changes or validation fails.

Worked example

Convert 1 W/(m·K) to Btu/(h·ft·°F). Multiply by 0.5777893165; the result is 0.5777893165 Btu/(h·ft·°F). The same input equals 1 W/(m·K) in the SI-base unit.

Accuracy and limitations

Conductivity depends on temperature, moisture, density, direction and material structure. It is not the same as whole-assembly U-value or R-value.

The calculator retains more digits internally than it displays. Round the final value to the precision supported by your measurement. Very large and very small answers may use scientific notation.

Frequently asked questions

Is thermal conductivity the inverse of R-value?

Not directly. Conductivity is a material property; R-value also depends on thickness and assembly geometry.

Can I reverse the conversion?

Yes. Swap the From and To selections. Because both units use the same SI base, the reverse factor is the reciprocal of the forward factor.

Why was my entry rejected?

Use digits with an optional decimal point or scientific notation. Blank values, commas, fractions, words and non-finite entries are rejected. Negative values are rejected because this converter treats the quantity as a magnitude.

Review notes and sources

Reviewed October 4, 2026. The conversion factors, default example, zero or signed boundary behavior, invalid-input handling and recovery after an error were checked. Factors follow SI definitions and published conversion guidance from the NIST Guide to the SI and the BIPM SI Brochure. Explanations and examples are original.

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