What's the difference between thermal conductivity and R-value?

Thermal conductivity (k) is a material property. R-value measures thermal resistance of a specific thickness: R = thickness / k. Higher R-value = better insulation. A 6-inch fiberglass batt has higher R-value than a 3-inch batt of the same material.

Why do metals conduct heat so well?

Metals have free electrons that move easily through the material, carrying thermal energy with them. This electron movement is the same mechanism that makes metals good electrical conductors. Materials without free electrons rely on slower atomic vibrations (phonons) for heat transfer.

How does thermal conductivity change with temperature?

For metals, conductivity generally decreases with temperature. For non-metals and insulators, conductivity typically increases with temperature. For gases, conductivity increases with temperature. Always check values at your operating temperature for accurate calculations.

What makes a good insulator?

Good insulators have low thermal conductivity. They typically trap air in small pockets (like foam or fiberglass) since still air is an excellent insulator at 0.024 W/m·K. The best insulators prevent convection within trapped air. Vacuum is even better but impractical for most applications.

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About Thermal Conductivity Conversion

Thermal conductivity measures a material's intrinsic ability to conduct heat—how easily heat energy passes through a substance. High thermal conductivity means heat passes through easily (like metals such as copper and aluminum); low conductivity means the material resists heat flow (like insulation materials, wood, and air). This property is described by Fourier's Law: heat flux is proportional to temperature gradient, with thermal conductivity as the proportionality constant.

The SI単位 is watts per meter kelvin (W/m·K), representing the heat power conducted through a material per unit temperature gradient. This fundamental material property is essential for insulation selection, heat sink and heat exchanger design, building envelope analysis, electronics thermal management, and any application involving heat conduction through solid materials. Thermal conductivity varies significantly between materials—from around 400 W/m·K for copper to 0.03 W/m·K for aerogel insulation.

Our converter handles all standard thermal conductivity units for materials science, building physics, and engineering applications.

Common Thermal Conductivity Conversions

変換元	変換先	乗数
W/m·K	BTU/hr·ft·°F	0.5778
BTU/hr·ft·°F	W/m·K	1.731
W/m·K	kcal/hr·m·°C	0.8598
kcal/hr·m·°C	W/m·K	1.163
W/m·K	W/cm·K	0.01
W/cm·K	W/m·K	100
W/m·K	cal/s·cm·°C	0.002388
BTU·in/hr·ft²·°F	W/m·K	0.1442

Thermal Conductivity 単位リファレンス

Watt per meter kelvin (W/m·K) – The SI単位 for thermal conductivity. Represents heat power conducted through a 1-meter thickness with 1-degree temperature difference across opposite faces. Used in engineering calculations worldwide. Common values: copper 385 W/m·K, aluminum 205 W/m·K, steel 50 W/m·K, glass 1 W/m·K, wood 0.15 W/m·K, air 0.024 W/m·K.

BTU per hour foot degree F (BTU/hr·ft·°F) – US customary unit used in building construction, HVAC industries, and insulation specifications. 1 BTU/hr·ft·°F = 1.731 W/m·K. Common in American building codes and material datasheets. R-value (thermal resistance) is calculated by dividing thickness (in feet) by this value.

BTU inch per hour square foot degree F (BTU·in/hr·ft²·°F) – Commonly used in US building industry when material thickness is specified in inches. Dividing by 12 converts to BTU/hr·ft·°F. Insulation R-values per inch are often derived from this unit. 1 BTU·in/hr·ft²·°F = 0.1442 W/m·K.

Kilocalorie per hour meter degree C (kcal/hr·m·°C) – Older metric unit still found in some European industrial and chemical engineering references. 1 kcal/hr·m·°C ≈ 1.163 W/m·K. Sometimes preferred in food processing industries.

Watt per centimeter kelvin (W/cm·K) – Used for highly conductive materials and electronics applications. 1 W/cm·K = 100 W/m·K. Convenient for thermal interface materials and heat spreader specifications.

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Explore our in-depth guides on this topic:

熱伝導率

About Thermal Conductivity Conversion

Common Thermal Conductivity Conversions

Thermal Conductivity 単位リファレンス

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