Convert BTU inch per hour per square foot per degree Fahrenheit to Watt per millimetre kelvin
Convert BTU inch per hour per square foot per degree Fahrenheit (BTU·in/(h·ft²·°F)) to Watt per millimetre kelvin (W/(mm·K)) instantly and accurately.
Conversion Formula
W/(mm·K) = BTU·in/(h·ft²·°F) × 0.0001442278889
About BTU inch per hour per square foot per degree Fahrenheit
The BTU·in/(h·ft²·°F) equals (1055.05585262 × 0.0254 × 9)/(3600 × 0.09290304 × 5) W/(m·K) ≈0.1442 W/(m·K). The standard US k-factor unit for insulation per ASTM C177, C335, and C518. Mineral wool ≈0.25; expanded polystyrene ≈0.24; polyurethane foam ≈0.14 BTU·in/(h·ft²·°F). 1 BTU·in/(h·ft²·°F) ≈0.1442 W/(m·K).
About Watt per millimetre kelvin
The watt per millimetre kelvin (W/(mm·K)) equals exactly 1000 W/(m·K) since 1 mm = 10⁻³ m. Used in microelectronics thermal engineering where components are millimetre-scale: copper ≈0.385, silicon ≈0.148 W/(mm·K). Thermal interface material datasheets for high-performance pads and solder joints commonly use this unit. 1 W/(mm·K) = 1000 W/(m·K) = 10 W/(cm·K).
Quick Reference Table
| BTU inch per hour per square foot per degree Fahrenheit (BTU·in/(h·ft²·°F)) | Watt per millimetre kelvin (W/(mm·K)) |
|---|---|
| 1 BTU·in/(h·ft²·°F) | 0.000144228 W/(mm·K) |
| 2 BTU·in/(h·ft²·°F) | 0.000288456 W/(mm·K) |
| 5 BTU·in/(h·ft²·°F) | 0.000721139 W/(mm·K) |
| 10 BTU·in/(h·ft²·°F) | 0.00144228 W/(mm·K) |
| 25 BTU·in/(h·ft²·°F) | 0.0036057 W/(mm·K) |
| 50 BTU·in/(h·ft²·°F) | 0.00721139 W/(mm·K) |
| 100 BTU·in/(h·ft²·°F) | 0.0144228 W/(mm·K) |