Convert BTU inch per hour per square foot per degree Fahrenheit to Watt per metre kelvin
Convert BTU inch per hour per square foot per degree Fahrenheit (BTU·in/(h·ft²·°F)) to Watt per metre kelvin (W/(m·K)) instantly and accurately.
Conversion Formula
W/(m·K) = BTU·in/(h·ft²·°F) × 0.1442278889
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 metre kelvin
The watt per metre kelvin (W/(m·K)) is the SI unit for thermal conductivity defined by Fourier's law q = -λ∇T. Materials span orders of magnitude: aerogels ≈0.015, glass ≈1.0, stainless steel ≈16, aluminium ≈205, copper ≈385, diamond ≈2200 W/(m·K). Referenced in ISO 22007, EN 12667, and all major international standards. 1 W/(m·K) = 1 W/(m·°C).
Quick Reference Table
| BTU inch per hour per square foot per degree Fahrenheit (BTU·in/(h·ft²·°F)) | Watt per metre kelvin (W/(m·K)) |
|---|---|
| 1 BTU·in/(h·ft²·°F) | 0.144228 W/(m·K) |
| 2 BTU·in/(h·ft²·°F) | 0.288456 W/(m·K) |
| 5 BTU·in/(h·ft²·°F) | 0.721139 W/(m·K) |
| 10 BTU·in/(h·ft²·°F) | 1.44228 W/(m·K) |
| 25 BTU·in/(h·ft²·°F) | 3.6057 W/(m·K) |
| 50 BTU·in/(h·ft²·°F) | 7.21139 W/(m·K) |
| 100 BTU·in/(h·ft²·°F) | 14.4228 W/(m·K) |