Thermal Conductivity Converter
Convert between thermal conductivity units including Watts per meter Kelvin and BTU per hour foot Fahrenheit.
Result
1 W/m·K = 0.01 W/cm·°C
Understanding Thermal Conductivity Units: Heat Transfer and K-Value Measurements
Thermal conductivity converters are essential tools for calculating how efficiently materials transfer heat, measuring heat flow per unit temperature gradient. Whether you're working with watts per meter kelvin (W/m·K), watts per centimeter celsius (W/cm·°C), kilowatts per meter kelvin (kW/m·K), calories per second centimeter celsius (cal/s·cm·°C), kilocalories per hour meter celsius (kcal/h·m·°C), British thermal units per hour foot fahrenheit (Btu/h·ft·°F), Btu inches per second square foot fahrenheit (Btu·in/s·ft²·°F), Btu feet per hour square foot fahrenheit (Btu·ft/h·ft²·°F), or Btu inches per hour square foot fahrenheit (Btu·in/h·ft²·°F), understanding thermal conductivity conversions is crucial for engineers, materials scientists, architects, and thermal analysts in heat transfer, building design, electronics cooling, HVAC, aerospace, and manufacturing industries.
Thermal conductivity measurements quantify a material's ability to conduct heat, directly related to thermal insulation, heat dissipation, and energy efficiency. From metals with high conductivity in W/m·K to insulating materials with low k-values, and from building materials in Btu·in/h·ft²·°F to electronics thermal interface materials in W/m·K, this comprehensive converter supports thirteen major thermal conductivity units with instant, accurate results for all your heat conduction and thermal design calculations across different industry standards and measurement systems.
How to Convert Thermal Conductivity Units: Formulas and Methods
W/m·K to W/cm·°C and kW/m·K Conversions
Converting from watts per meter kelvin (W/m·K) to watts per centimeter celsius (W/cm·°C) requires multiplying by 0.01, since 1 W/cm·°C equals 100 W/m·K due to the 100-centimeter-per-meter conversion. Similarly, converting to kilowatts per meter kelvin (kW/m·K) divides by 1000, since 1 kW/m·K equals 1000 W/m·K. These SI-based conversions are straightforward, with W/m·K serving as the fundamental SI unit for thermal conductivity in engineering and scientific applications worldwide.
Calorie-Based Thermal Conductivity Units
Converting from W/m·K to calorie IT per second centimeter celsius (cal IT/(s·cm·°C)) multiplies by approximately 0.002388, since 1 cal IT/(s·cm·°C) equals 418.68 W/m·K. Kilocalorie per hour meter celsius (kcal/(h·m·°C)) uses approximately 1.163 W/m·K per kcal/(h·m·°C). International Table (IT) calorie equals 4.1868 J, while thermochemical (th) calorie equals 4.184 J, creating small but significant differences in precision calculations for thermal interface materials and building insulation specifications.
British Thermal Unit Hour-Based Conversions
Converting from W/m·K to Btu IT per hour foot fahrenheit (Btu·ft/(h·ft²·°F)) multiplies by approximately 0.5778, since 1 Btu·ft/(h·ft²·°F) equals 1.730735 W/m·K. This unit appears frequently in American building codes, insulation specifications, and HVAC engineering, where R-value calculations and thermal resistance measurements use Imperial system units. The thermochemical variant (Btu th·ft/(h·ft²·°F)) equals 1.729577 W/m·K, reflecting the small Btu definition difference.
British Thermal Unit Second-Based Conversions
Btu-based units with seconds (s) instead of hours (h) represent thermal conductivity on different time scales. Btu IT per second inch square foot fahrenheit (Btu·in/(s·ft²·°F)) equals 518.873 W/m·K, significantly larger than hour-based units due to the 3600-second-per-hour conversion. These high-magnitude units help engineers work with transient heat transfer, rapid thermal pulses, and dynamic cooling systems where second-scale measurements provide better resolution than hour-based thermal conductivity values.
Thermal Conductivity, Resistance, and Insulation R-Value Relationships
Thermal conductivity (k), thermal resistance (R), and R-value relate through k = t/R for homogeneous materials, where t is thickness. High conductivity materials (metals: 15-400 W/m·K) conduct heat well, while low conductivity materials (insulation: 0.02-0.1 W/m·K) resist heat flow. R-value in building construction uses Btu·in/(h·ft²·°F) or SI equivalents, calculated as R = t/k, demonstrating the inverse relationship between conductivity and insulation effectiveness across all unit systems.
Thermal Conductivity Conversion Reference Table
| W/m·K | W/cm·°C | kW/m·K | cal/(s·cm·°C) IT | kcal/(h·m·°C) IT | Btu·ft/(h·ft²·°F) IT |
|---|---|---|---|---|---|
| 0.02 | 0.0002 | 0.00002 | 0.000048 | 0.017 | 0.012 |
| 0.04 | 0.0004 | 0.00004 | 0.000096 | 0.034 | 0.023 |
| 0.1 | 0.001 | 0.0001 | 0.000239 | 0.086 | 0.058 |
| 0.2 | 0.002 | 0.0002 | 0.000478 | 0.172 | 0.116 |
| 1 | 0.01 | 0.001 | 0.002389 | 0.860 | 0.578 |
| 2 | 0.02 | 0.002 | 0.004778 | 1.720 | 1.156 |
| 50 | 0.5 | 0.05 | 0.119448 | 43.000 | 28.888 |
| 100 | 1 | 0.1 | 0.238896 | 86.000 | 57.776 |
| 200 | 2 | 0.2 | 0.477792 | 172.000 | 115.552 |
| 400 | 4 | 0.4 | 0.955584 | 344.000 | 231.104 |
Common Material Thermal Conductivity Values (at 20°C)
| Material | W/m·K | W/cm·°C | Btu·ft/(h·ft²·°F) |
|---|---|---|---|
| Air (dry, still) | 0.025 | 0.00025 | 0.014 |
| Foam Insulation | 0.03 | 0.0003 | 0.017 |
| Fiberglass | 0.04 | 0.0004 | 0.023 |
| Wood (oak) | 0.17 | 0.0017 | 0.098 |
| Water | 0.6 | 0.006 | 0.347 |
| Glass | 1.0 | 0.01 | 0.578 |
| Concrete | 1.4 | 0.014 | 0.809 |
| Aluminum | 205 | 2.05 | 118.4 |
| Copper | 400 | 4 | 231.1 |
| Silver | 429 | 4.29 | 247.8 |
Industry Applications and Use Cases
Building Construction and Insulation Design
Architects use thermal conductivity measurements in W/m·K or Btu·in/(h·ft²·°F) to select insulation materials, calculate heat loss through walls and roofs, and design energy-efficient buildings. Converting between SI and Imperial units enables international collaboration, where European insulation specifications in W/m·K must meet American R-value requirements in Btu·in/(h·ft²·°F) for code compliance and certification.
Electronics Cooling and Heat Dissipation
Electronics engineers specify thermal conductivities in W/m·K for heat sinks, thermal interface materials, and PCB substrates to manage component temperatures. High conductivity materials like copper (400 W/m·K) and aluminum (205 W/m·K) dissipate heat from processors, while low conductivity materials insulate sensitive components. Unit conversion ensures compatibility with international thermal management specifications.
HVAC and Energy Efficiency Engineering
HVAC professionals convert between W/m·K and Btu·ft/(h·ft²·°F) when designing duct insulation, calculating pipe heat losses, and selecting thermal barriers. Building energy modeling requires accurate conductivity values in specific units to predict heating and cooling loads, while energy codes often specify different unit systems depending on regional standards.
Materials Science and Composite Development
Materials scientists measure and compare thermal conductivities across different unit systems when developing new composites, ceramics, and polymers. Aerospace applications require precise k-value measurements in W/m·K, while automotive thermal management often uses Imperial units. Researchers convert units to compare data from international publications and collaborate on material optimization projects.
Frequently Asked Questions
What is thermal conductivity and why is it important?
Thermal conductivity (k) measures how well a material conducts heat per unit temperature gradient. High k-values (metals: 50-400 W/m·K) mean efficient heat transfer, while low values (insulation: 0.02-0.1 W/m·K) mean good insulation. It's crucial for designing heat sinks, insulation systems, thermal barriers, and energy-efficient buildings.
How do I convert W/m·K to W/cm·°C?
Multiply W/m·K by 0.01 to get W/cm·°C, since 1 W/cm·°C equals 100 W/m·K due to the 100 centimeters per meter conversion. For example, copper's 400 W/m·K equals 4 W/cm·°C, demonstrating the scale difference in CGS-derived units.
How to convert W/m·K to Btu·ft/(h·ft²·°F)?
Multiply W/m·K by 0.5778 to get Btu IT·ft/(h·ft²·°F), since 1 Btu IT·ft/(h·ft²·°F) equals 1.731 W/m·K. For example, aluminum's 205 W/m·K equals approximately 118 Btu·ft/(h·ft²·°F), common in American building and HVAC specifications.
What's the difference between Btu IT and Btu th?
International Table Btu (IT) equals 1055.06 J while thermochemical Btu (th) equals 1054.35 J - a 0.067% difference. In thermal conductivity, 1 Btu IT·ft/(h·ft²·°F) = 1.731 W/m·K versus 1 Btu th·ft/(h·ft²·°F) = 1.730 W/m·K. Use IT for general engineering and th for thermodynamic applications.
How does thermal conductivity relate to insulation R-value?
R-value equals thickness divided by thermal conductivity (R = t/k). Materials with lower k-values provide higher R-values for the same thickness. Fiberglass (k = 0.04 W/m·K) gives R-value ≈ 25 t (in meters), while high conductivity metals provide negligible insulation despite any thickness.
What are typical thermal conductivity values for common materials?
Metals: copper 400, aluminum 205, steel 50 W/m·K. Insulators: fiberglass 0.04, foam 0.03, air 0.025 W/m·K. Building materials: concrete 1.4, wood 0.17, glass 1.0 W/m·K. Higher values conduct heat better, lower values insulate better.
Why are there so many different thermal conductivity units?
Different industries use different measurement systems: SI (W/m·K) for international science, CGS-derived (cal/s·cm·°C) for older literature, Imperial (Btu-based) for American construction. Engineers must convert units when sourcing materials globally, comparing specifications, and designing systems compatible with multiple standards.
How do time scales affect thermal conductivity units?
Btu·in/(s·ft²·°F) uses seconds (s) versus hours (h) in Btu·in/(h·ft²·°F), creating 3600x factor differences. Second-based units help analyze rapid heat transfer, transient thermal pulses, and dynamic cooling. Hour-based units suit steady-state building and HVAC calculations.
Are Kelvin and Celsius interchangeable in thermal conductivity?
Yes! W/m·K and W/m·°C are numerically identical since Kelvin and Celsius intervals are the same size. Temperature differences (ΔT) don't depend on absolute temperature, so thermal conductivity measurements use K and °C interchangeably in unit conversions.
How accurate are thermal conductivity conversions?
Our converter uses exact mathematical relationships with 10-decimal precision. Conversions are precise except for slight variations between IT and th definitions (0.067% difference). These accurate conversions support engineering calculations requiring exact thermal conductivity values.
How does thermal conductivity vary with temperature?
Thermal conductivity changes with temperature: metals decrease, insulators may increase, and gases increase substantially. Most reference values use 20°C or 25°C. Temperature-dependent k-values require corrections for high-temperature applications in furnaces, engines, or cryogenic systems.
Can thermal conductivity be negative?
Normal materials always have positive thermal conductivity. Negative thermal conductivity could theoretically occur in exotic materials under specific conditions, but all practical engineering applications use positive k-values. Thermal diffusivity, which combines conductivity with heat capacity, can appear in transient analysis.
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