Convert thermal conductivity values between metric and imperial units instantly — essential for heat transfer calculations, insulation design, and material selection.
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The Thermal Conductivity Converter moves a value between W/m·K, W/m·°C, BTU/h·ft·°F, BTU·in/h·ft²·°F, kcal/h·m·°C and kJ/h·m·°C. Thermal conductivity is a material ability to conduct heat — the SI unit is watts per meter per kelvin (W/m·K), and it is an intrinsic material property, unlike the heat transfer coefficient.
The cross-system conversion is W/m·K ↔ BTU/h·ft·°F. Using the International Table BTU, 1 BTU/h·ft·°F = 1.730735 W/m·K. The related unit BTU·in/h·ft²·°F (used for insulation) equals 0.1442279 W/m·K. The kcal and cal units here use the International Table calorie (4.1868 J). W/m·K and W/m·°C are numerically identical. Values range from ~0.03 W/m·K for insulation to ~400 W/m·K for copper.
1 BTU/h·ft·°F = 1.73074 W/m·K (International Table BTU). W/m·K = W/m·°C.
| W/m·K | BTU/h·ft·°F |
|---|---|
| 0.03 | 0.0173 |
| 0.1 | 0.0578 |
| 0.5 | 0.2889 |
| 1 | 0.5778 |
| 5 | 2.8889 |
| 20 | 11.5558 |
| 50 | 28.8895 |
| 100 | 57.7789 |
| 200 | 115.5578 |
| 400 | 231.1157 |
150 W/mK → BTU/hr·ft·°F
50 W/m·K = 28.88946 BTU/hr·ft·°F
50 W/m·K = 28.88946 BTU/hr·ft·°F
21 BTU/hr·ft·°F → W/mK
1 BTU/hr·ft·°F = 1.730735 W/m·K
1 BTU/hr·ft·°F = 1.730735 W/m·K
30.04 W/mK → BTU·in/hr·ft²·°F
0.04 W/m·K = 0.277339 BTU·in/hr·ft²·°F
0.04 W/m·K = 0.277339 BTU·in/hr·ft²·°F
410 kcal/hr·m·°C → W/mK
10 kcal (IT)/hr·m·°C = 11.63 W/m·K
10 kcal (IT)/hr·m·°C = 11.63 W/m·K
5400 W/mK → BTU/hr·ft·°F
400 W/m·K = 231.115682 BTU/hr·ft·°F
400 W/m·K = 231.115682 BTU/hr·ft·°F
60.03 W/mK → kcal/hr·m·°C
0.03 W/m·K = 0.025795 kcal (IT)/hr·m·°C
0.03 W/m·K = 0.025795 kcal (IT)/hr·m·°C
Familiar material conductivities that make a converted value easier to picture.
Fiberglass insulation
≈ 0.04 W/m·K ≈ 0.28 BTU·in/h·ft²·°F
Water
≈ 0.6 W/m·K
Aluminum
≈ 205 W/m·K ≈ 118 BTU/h·ft·°F
Copper
≈ 400 W/m·K ≈ 231 BTU/h·ft·°F
1 BTU/h·ft·°F
1.731 W/m·K
Stainless steel
≈ 16 W/m·K
Watt per meter-kelvinW/m·K
The SI derived unit of thermal conductivity, an intrinsic material property. Identical to W/m·°C. Copper ≈ 400 W/m·K, insulation ≈ 0.03 W/m·K.
BTU per hour-foot-°FBTU/h·ft·°F
1.730735 W/m·K. The US unit for material thermal conductivity.
BTU·inch per hour-square foot-°FBTU·in/h·ft²·°F
0.1442279 W/m·K. The US unit commonly used for building insulation (per-inch thickness).
Kilocalorie per hour-meter-°Ckcal/h·m·°C
1.163 W/m·K. Used in older European thermal literature.
Thermal conductivity conversion appears in material selection, insulation and heat-transfer modeling.
The W/m·K to BTU/h·ft·°F factor 1.730735 derives from the International Table BTU and exact foot definition. W/m·K and W/m·°C are identical. FlowUtil computes with full precision and rounds only the display.
Thermal conductivity varies with temperature, moisture and alloy, so two or three significant figures normally reflect the material. Keep more decimals only for measured lab data and state the temperature.