Thermal Conductivity Converter

Convert non-negative thermal conductivity between W/(m·K), W/(cm·K), kW/(m·K), cal/(cm·s·°C), kcal/(m·h·°C), and BTU-based conductivity units.

Heat transfer

Convert thermal conductivity across SI, calorie, and BTU-based units

Restate a material or fluid conductivity value without confusing it with conductance, heat flux, or overall U-values.

Quick presets

Scope note

This page converts thermal conductivity only. It does not calculate insulation performance, R-value, overall heat-transfer coefficient, or heat-loss rate through a chosen assembly thickness.

Enter values Provide a thermal conductivity value and source unit to calculate the full conversion sheet.

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Heat Transfer

Thermal conductivity converter: W/(m·K), calorie-based, and BTU-based units explained

A thermal conductivity converter rewrites the same material property in the unit your lab note, insulation table, process reference, or engineering specification expects. That matters because thermal conductivity is not the same thing as conductance, heat-transfer coefficient, or total heat loss through a wall.

What thermal conductivity measures

Thermal conductivity describes how readily heat moves through a material when a temperature gradient exists. It is a material or fluid property, not a whole-assembly performance score.

The same conductivity value can be written in W/(m·K), W/(cm·K), kcal/(m·h·°C), cal/(cm·s·°C), or BTU-based units without changing the underlying property being described.

q = -k A (dT/dx)

Fourier-law form showing conductivity k as the proportionality term in one-dimensional conduction.

1 W/(cm·K) = 100 W/(m·K)

Links the metre-based and centimetre-based SI forms used in property tables.

1 BTU/(ft·h·°F) ≈ 1.73073 W/(m·K)

Shows the common imperial-to-SI relationship used by this page.

Why conductivity is not the same as conductance or R-value

Thermal conductivity belongs to the material itself. Conductance, U-value, and R-value depend on thickness, geometry, layers, and boundary conditions. Changing the unit on this page does not convert one of those assembly measures into another.

That distinction matters when you move between material datasheets and building-envelope calculations. A conductivity value may be one input to a larger heat-loss model, but it is not the model result.

How to use the result responsibly

Use the converter when a source table, vendor sheet, or test report expresses conductivity in a unit system different from the one used in your own workflow. The table view is especially useful when SI, calorie-based, and BTU-based references all appear in the same project.

Do not assume conductivity is fixed under every condition. Many materials vary with temperature, moisture content, density, orientation, or composition, so the converted value is only as applicable as the original reported measurement.

Further reading

Frequently asked questions

Is thermal conductivity the same as thermal conductance?

No. Conductivity is a material property. Conductance depends on the material plus geometry such as thickness and area.

 Can I use this page to convert R-values or U-values?

No. R-values and U-values describe whole-layer or assembly performance. This page converts conductivity units only.

 Why can published conductivity values vary for the same material?

Because conductivity can change with temperature, moisture, density, composition, grain direction, and the exact test method used.

 Why do BTU-based conductivity units still appear?

They remain common in older engineering references, HVAC material data, and some US-focused specifications, so conversion is useful when comparing with SI sources.

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