Convert thermal conductivity units — W/(m·K), BTU/(h·ft·°F), cal/(s·cm·°C) and more.
| Unit | Name | Value |
|---|---|---|
| W/(m·K) | Watt/(Meter·Kelvin) | 1.73073 |
| kW/(m·K) | Kilowatt/(Meter·Kelvin) | 0.00173073 |
| cal/(s·cm·°C) | Calorie/(Second·cm·°C) | 0.0041337776 |
| kcal/(h·m·°C) | Kilocalorie/(Hour·m·°C) | 1.4881599 |
Formula: W/(m·K) = BTU/(h·ft·°F) × 1.731
Multiply any BTU/(h·ft·°F) value by 1.731 to get W/(m·K).
Reverse: BTU/(h·ft·°F) = W/(m·K) × 0.5778
Copper reference: 231.7 BTU/(h·ft·°F) = 401 W/(m·K)
Factor: 1 BTU/(h·ft·°F) = 1.731 W/(m·K)
| BTU/(h·ft·°F) (BTU/(h·ft·°F)) | W/(m·K) (W/(m·K)) | Material |
|---|---|---|
| 1271 BTU/(h·ft·°F) | 2200 W/(m·K) | Diamond |
| 247.9 BTU/(h·ft·°F) | 429 W/(m·K) | Silver |
| 231.7 BTU/(h·ft·°F) | 401 W/(m·K) | Copper |
| 183.7 BTU/(h·ft·°F) | 318 W/(m·K) | Gold |
| 136.9 BTU/(h·ft·°F) | 237 W/(m·K) | Aluminum |
| 30.05 BTU/(h·ft·°F) | 52 W/(m·K) | Cast iron |
| 28.89 BTU/(h·ft·°F) | 50 W/(m·K) | Steel (carbon) |
| 1.444 BTU/(h·ft·°F) | 2.5 W/(m·K) | Marble |
| 0.9822 BTU/(h·ft·°F) | 1.7 W/(m·K) | Concrete |
| 0.5778 BTU/(h·ft·°F) | 1 W/(m·K) | Glass |
| 0.3467 BTU/(h·ft·°F) | 0.6 W/(m·K) | Water (20°C) |
| 0.09822 BTU/(h·ft·°F) | 0.17 W/(m·K) | Wood (oak) |
| 0.02311 BTU/(h·ft·°F) | 0.04 W/(m·K) | Fiberglass batt |
| 0.01502 BTU/(h·ft·°F) | 0.026 W/(m·K) | Air (25°C) |
| 0.008667 BTU/(h·ft·°F) | 0.015 W/(m·K) | Aerogel |
BTU/(h·ft·°F) × 1.7307 = W/(m·K). Round to × 1.73.
1 BTU/(h·ft·°F) = 1.731 W/(m·K). 0.578 = 1.0 W/(m·K) (glass).
W/(m·K) × 0.5779 = BTU/(h·ft·°F).
Specifies insulation and wall assembly thermal conductivity in W/(m·K) for energy compliance calculations.
Uses BTU/(h·ft·°F) for US building code compliance and W/(m·K) for metric heat transfer calculations.
Compares thermal conductivity of metals, polymers, and composites in W/(m·K) for thermal management design.
Selects thermal interface materials and heatsinks using conductivity data in W/(m·K).
Designs heat exchangers using shell and tube thermal conductivity specifications in W/(m·K).
Measures and reports thermal conductivity of novel materials (graphene, CNTs, aerogels) in W/(m·K) or kW/(m·K).
BTU per hour per foot per degree Fahrenheit (BTU/(h·ft·°F)) is the Imperial thermal conductivity unit, equal to 1.73073 W/(m·K). It is the standard in US building codes, insulation specifications, and HVAC engineering.
US building energy codes (ASHRAE, IBC) specify insulation conductivity in BTU/(h·ft·°F). R-values in North American insulation are derived from this unit: R-value = thickness (inches) ÷ (k × 12), where k is in BTU/(h·ft·°F). Air = 0.015 BTU/(h·ft·°F); fiberglass batt = 0.025 BTU/(h·ft·°F).
Interesting fact: US insulation is marketed using R-values (thermal resistance), not k-values (conductivity). R-13 wall insulation has a conductivity of about 0.025 BTU/(h·ft·°F). The confusion between R-value and k-value is a common source of error in building energy calculations.
Watt per meter per kelvin (W/(m·K)) is the SI unit of thermal conductivity. It measures the rate of heat transfer through a material of 1 meter thickness per kelvin of temperature difference per unit area. It was formally defined with the SI system in 1960.
W/(m·K) is universally used in engineering and science for specifying material thermal properties. Key values: air = 0.026 W/(m·K); water = 0.6 W/(m·K); glass = 1.0 W/(m·K); concrete = 1.7 W/(m·K); steel = 50 W/(m·K); copper = 401 W/(m·K); diamond = 2,200 W/(m·K).
Interesting fact: Diamond has the highest thermal conductivity of any natural material at about 2,200 W/(m·K) — nearly 6× that of copper and 85,000× that of air. This is why diamond heatsinks are used in high-power laser diodes and some semiconductor devices.
Thermal conductivity measures how readily a material conducts heat. The SI unit W/(m·K) is universal in science; US building codes use BTU/(h·ft·°F); older European engineering uses kcal/(h·m·°C); CGS physics uses cal/(s·cm·K). Key anchors: air 0.026 W/(m·K), glass 1.0, steel 50, copper 401, diamond 2,200.
Exact factor: 1 BTU/(h·ft·°F) = 1.731 W/(m·K). Reverse: 1 W/(m·K) = 0.5778 BTU/(h·ft·°F).
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.