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: kcal/(h·m·°C) = BTU/(h·ft·°F) × 1.488
Multiply any BTU/(h·ft·°F) value by 1.488 to get kcal/(h·m·°C).
Reverse: BTU/(h·ft·°F) = kcal/(h·m·°C) × 0.672
Copper reference: 231.7 BTU/(h·ft·°F) = 344.8 kcal/(h·m·°C)
Factor: 1 BTU/(h·ft·°F) = 1.488 kcal/(h·m·°C)
| BTU/(h·ft·°F) (BTU/(h·ft·°F)) | kcal/(h·m·°C) (kcal/(h·m·°C)) | Material |
|---|---|---|
| 1271 BTU/(h·ft·°F) | 1892 kcal/(h·m·°C) | Diamond |
| 247.9 BTU/(h·ft·°F) | 368.9 kcal/(h·m·°C) | Silver |
| 231.7 BTU/(h·ft·°F) | 344.8 kcal/(h·m·°C) | Copper |
| 183.7 BTU/(h·ft·°F) | 273.4 kcal/(h·m·°C) | Gold |
| 136.9 BTU/(h·ft·°F) | 203.8 kcal/(h·m·°C) | Aluminum |
| 30.05 BTU/(h·ft·°F) | 44.71 kcal/(h·m·°C) | Cast iron |
| 28.89 BTU/(h·ft·°F) | 42.99 kcal/(h·m·°C) | Steel (carbon) |
| 1.444 BTU/(h·ft·°F) | 2.15 kcal/(h·m·°C) | Marble |
| 0.9822 BTU/(h·ft·°F) | 1.462 kcal/(h·m·°C) | Concrete |
| 0.5778 BTU/(h·ft·°F) | 0.8598 kcal/(h·m·°C) | Glass |
| 0.3467 BTU/(h·ft·°F) | 0.5159 kcal/(h·m·°C) | Water (20°C) |
| 0.09822 BTU/(h·ft·°F) | 0.1462 kcal/(h·m·°C) | Wood (oak) |
| 0.02311 BTU/(h·ft·°F) | 0.03439 kcal/(h·m·°C) | Fiberglass batt |
| 0.01502 BTU/(h·ft·°F) | 0.02236 kcal/(h·m·°C) | Air (25°C) |
| 0.008667 BTU/(h·ft·°F) | 0.0129 kcal/(h·m·°C) | Aerogel |
BTU/(h·ft·°F) × 0.672 = kcal/(h·m·°C).
1 BTU/(h·ft·°F) = 0.672 kcal/(h·m·°C).
kcal/(h·m·°C) × 1.488 = 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.
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.
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) = 1.488 kcal/(h·m·°C). Reverse: 1 kcal/(h·m·°C) = 0.672 BTU/(h·ft·°F).
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.