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) | 1.163 |
| kW/(m·K) | Kilowatt/(Meter·Kelvin) | 0.001163 |
| BTU/(h·ft·°F) | BTU/(Hour·Foot·°F) | 0.67197079 |
| cal/(s·cm·°C) | Calorie/(Second·cm·°C) | 0.0027777778 |
Formula: BTU/(h·ft·°F) = kcal/(h·m·°C) × 0.672
Multiply any kcal/(h·m·°C) value by 0.672 to get BTU/(h·ft·°F).
Reverse: kcal/(h·m·°C) = BTU/(h·ft·°F) × 1.488
Copper reference: 344.8 kcal/(h·m·°C) = 231.7 BTU/(h·ft·°F)
Factor: 1 kcal/(h·m·°C) = 0.672 BTU/(h·ft·°F)
| kcal/(h·m·°C) (kcal/(h·m·°C)) | BTU/(h·ft·°F) (BTU/(h·ft·°F)) | Material |
|---|---|---|
| 1892 kcal/(h·m·°C) | 1271 BTU/(h·ft·°F) | Diamond |
| 368.9 kcal/(h·m·°C) | 247.9 BTU/(h·ft·°F) | Silver |
| 344.8 kcal/(h·m·°C) | 231.7 BTU/(h·ft·°F) | Copper |
| 273.4 kcal/(h·m·°C) | 183.7 BTU/(h·ft·°F) | Gold |
| 203.8 kcal/(h·m·°C) | 136.9 BTU/(h·ft·°F) | Aluminum |
| 44.71 kcal/(h·m·°C) | 30.05 BTU/(h·ft·°F) | Cast iron |
| 42.99 kcal/(h·m·°C) | 28.89 BTU/(h·ft·°F) | Steel (carbon) |
| 2.15 kcal/(h·m·°C) | 1.444 BTU/(h·ft·°F) | Marble |
| 1.462 kcal/(h·m·°C) | 0.9822 BTU/(h·ft·°F) | Concrete |
| 0.8598 kcal/(h·m·°C) | 0.5778 BTU/(h·ft·°F) | Glass |
| 0.5159 kcal/(h·m·°C) | 0.3467 BTU/(h·ft·°F) | Water (20°C) |
| 0.1462 kcal/(h·m·°C) | 0.09822 BTU/(h·ft·°F) | Wood (oak) |
| 0.03439 kcal/(h·m·°C) | 0.02311 BTU/(h·ft·°F) | Fiberglass batt |
| 0.02236 kcal/(h·m·°C) | 0.01502 BTU/(h·ft·°F) | Air (25°C) |
| 0.0129 kcal/(h·m·°C) | 0.008667 BTU/(h·ft·°F) | Aerogel |
1 kcal/(h·m·°C) = 0.672 BTU/(h·ft·°F).
Copper ≈ 401 W/(m·K). Steel ≈ 50 W/(m·K). Glass ≈ 1 W/(m·K). Air ≈ 0.026 W/(m·K).
Multiply result by 1.488 to recover the original kcal/(h·m·°C) 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).
Kilocalorie per hour per meter per degree Celsius (kcal/(h·m·°C)) equals 1.163 W/(m·K). It was used in older European engineering texts and some industrial specifications, particularly in countries using kcal for thermal calculations before SI adoption.
kcal/(h·m·°C) appears in older continental European building physics, heat exchanger design manuals, and some Russian and Eastern European engineering standards. Steel ≈ 43 kcal/(h·m·°C); concrete ≈ 1.46 kcal/(h·m·°C); air ≈ 0.022 kcal/(h·m·°C).
Interesting fact: The kcal was the standard energy unit in continental European engineering before SI adoption in the 1970s–1980s. Many countries' building codes still include kcal-based thermal conductivity values in older editions, requiring conversion when working with modern SI specifications.
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.
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 kcal/(h·m·°C) = 0.672 BTU/(h·ft·°F). Reverse: 1 BTU/(h·ft·°F) = 1.488 kcal/(h·m·°C).
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.