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: cal/(s·cm·K) = BTU/(h·ft·°F) × 0.004134
Multiply any BTU/(h·ft·°F) value by 0.004134 to get cal/(s·cm·K).
Reverse: BTU/(h·ft·°F) = cal/(s·cm·K) × 241.9
Copper reference: 231.7 BTU/(h·ft·°F) = 0.9578 cal/(s·cm·K)
Factor: 1 BTU/(h·ft·°F) = 0.004134 cal/(s·cm·K)
| BTU/(h·ft·°F) (BTU/(h·ft·°F)) | cal/(s·cm·K) (cal/(s·cm·K)) | Material |
|---|---|---|
| 1271 BTU/(h·ft·°F) | 5.255 cal/(s·cm·K) | Diamond |
| 247.9 BTU/(h·ft·°F) | 1.025 cal/(s·cm·K) | Silver |
| 231.7 BTU/(h·ft·°F) | 0.9578 cal/(s·cm·K) | Copper |
| 183.7 BTU/(h·ft·°F) | 0.7595 cal/(s·cm·K) | Gold |
| 136.9 BTU/(h·ft·°F) | 0.5661 cal/(s·cm·K) | Aluminum |
| 30.05 BTU/(h·ft·°F) | 0.1242 cal/(s·cm·K) | Cast iron |
| 28.89 BTU/(h·ft·°F) | 0.1194 cal/(s·cm·K) | Steel (carbon) |
| 1.444 BTU/(h·ft·°F) | 0.005971 cal/(s·cm·K) | Marble |
| 0.9822 BTU/(h·ft·°F) | 0.00406 cal/(s·cm·K) | Concrete |
| 0.5778 BTU/(h·ft·°F) | 0.002388 cal/(s·cm·K) | Glass |
| 0.3467 BTU/(h·ft·°F) | 0.001433 cal/(s·cm·K) | Water (20°C) |
| 0.09822 BTU/(h·ft·°F) | 0.000406 cal/(s·cm·K) | Wood (oak) |
| 0.02311 BTU/(h·ft·°F) | 9.554e-05 cal/(s·cm·K) | Fiberglass batt |
| 0.01502 BTU/(h·ft·°F) | 6.210e-05 cal/(s·cm·K) | Air (25°C) |
| 0.008667 BTU/(h·ft·°F) | 3.583e-05 cal/(s·cm·K) | Aerogel |
1 BTU/(h·ft·°F) = 0.004134 cal/(s·cm·K).
Copper ≈ 401 W/(m·K). Steel ≈ 50 W/(m·K). Glass ≈ 1 W/(m·K). Air ≈ 0.026 W/(m·K).
Multiply result by 241.9 to recover the original BTU/(h·ft·°F) value.
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.
Calorie per second per centimeter per kelvin (cal/(s·cm·K)) is the CGS unit of thermal conductivity, equal to 418.68 W/(m·K). It was the standard in pre-SI physics and chemistry literature.
Cal/(s·cm·K) appears in older scientific handbooks and classic thermodynamics texts. Copper in CGS = 0.923 cal/(s·cm·K); iron = 0.179 cal/(s·cm·K); water = 0.00143 cal/(s·cm·K). The unit is rarely used in modern practice.
Interesting fact: The CGS unit cal/(s·cm·K) is 418.68× larger than W/(m·K) — so most materials have very small values in CGS. Water at 0.00143 cal/(s·cm·K) demonstrates why the CGS unit became impractical for most engineering applications.
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) = 0.004134 cal/(s·cm·K). Reverse: 1 cal/(s·cm·K) = 241.9 BTU/(h·ft·°F).
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.