Thermal Resistance Conversion - Convert K/W, °C/W, °F·hr/BTU, and More
Thermal Resistance Converter
Convert thermal resistance measurements between different units quickly and accurately
Convert Thermal Resistance
Popular Thermal Resistance Conversions
Quickly convert between the most commonly used thermal resistance units.
Understanding Thermal Resistance Measurements
Thermal resistance is a key parameter in electronics cooling, HVAC, and heat transfer engineering. The kelvin per watt (K/W) is the SI base unit, while °F·hr/BTU (IT), °F·hr/BTU (th), °F·s/BTU (IT), and °F·s/BTU (th) are used in North American and scientific contexts. Our converter supports all industry-standard units with BTU IT/th precision.
Industry-Standard Thermal Resistance Units
SI Unit
- Kelvin per watt (K/W) - International System base unit
Imperial & Scientific Units
- Fahrenheit-hour per BTU (IT) (°F·hr/BTU) - International Table BTU
- Fahrenheit-hour per BTU (th) (°F·hr/BTU) - Thermochemical BTU
- Fahrenheit-second per BTU (IT) (°F·s/BTU) - International Table BTU
- Fahrenheit-second per BTU (th) (°F·s/BTU) - Thermochemical BTU
Common Applications
| Field | Common Units | Typical Uses |
|---|---|---|
| Electronics | K/W | Heat sink design, chip cooling, junction-to-case analysis |
| HVAC | °F·hr/BTU (IT), °F·hr/BTU (th) | Heating, ventilation, air conditioning |
| Thermal Engineering | K/W, °F·hr/BTU (IT) | Heat transfer, insulation, scientific research |
Conversion Tips
- 1 K/W = 0.527527926314 °F·hr/BTU (IT)
- 1 K/W = 0.52717499999 °F·hr/BTU (th)
- 1 K/W = 1899.10041512 °F·s/BTU (IT)
- 1 K/W = 1897.8303055 °F·s/BTU (th)
- BTU (IT) and BTU (th) differ by ~0.07%
- Higher thermal resistance means better insulation or lower heat flow
Thermal Resistance Conversions
| Conversion | Formula | Quick Answer |
|---|---|---|
| K/W to °F·hr/BTU (IT) | 1 K/W = 1.8956342406 °F·hr/BTU (IT) | Multiply by 1.8956342406 |
| K/W to °F·hr/BTU (th) | 1 K/W = 1.8969293134 °F·hr/BTU (th) | Multiply by 1.8969293134 |
| K/W to °F·s/BTU (IT) | 1 K/W = 0.0005265651 °F·s/BTU (IT) | Multiply by 0.0005265651 |
| K/W to °F·s/BTU (th) | 1 K/W = 0.0005269175 °F·s/BTU (th) | Multiply by 0.0005269175 |
| °F·hr/BTU (IT) to °F·hr/BTU (th) | 1 °F·hr/BTU (IT) = 1.000682 °F·hr/BTU (th) | Multiply by 1.000682 |
| °F·s/BTU (IT) to °F·s/BTU (th) | 1 °F·s/BTU (IT) = 1.000669 °F·s/BTU (th) | Multiply by 1.000669 |
Our thermal resistance conversion tool provides accurate, industry-standard conversions between K/W and all major °F·hr/BTU and °F·s/BTU units, including both International Table and thermochemical BTU definitions. Use it for electronics, HVAC, and scientific applications requiring precise thermal resistance calculations.
Thermal Resistance Questions
Everything you need to know about thermal resistance measurements and conversions
What is thermal resistance and how does it work?
Thermal resistance is a measure of a material's or system's ability to resist heat flow. It's analogous to electrical resistance - higher thermal resistance means less heat transfer. It's calculated as the temperature difference divided by heat flow rate (R = ΔT/Q). Thermal resistance is the reciprocal of thermal conductance.
What's the difference between BTU (IT) and BTU (th) in thermal resistance units?
BTU (IT) refers to International Table BTU (1055.05585262 J), while BTU (th) refers to thermochemical BTU (1054.35026444 J). The difference is about 0.07%, but it's crucial for precision engineering applications. BTU (IT) is more commonly used in modern thermal calculations and HVAC applications.
Why do we use K/W and °F⋅hr/BTU units for thermal resistance?
K/W (or °C/W) is the SI standard used globally for electronics and scientific applications. °F⋅hr/BTU is traditional in North American HVAC and building industry. Both measure the same physical quantity - temperature rise per unit power - but serve different industry standards and regional preferences.
How do thermal resistances combine in series and parallel?
In series (heat flows through materials sequentially): R_total = R₁ + R₂ + R₃. In parallel (heat flows through materials simultaneously): 1/R_total = 1/R₁ + 1/R₂ + 1/R₃. This is identical to electrical resistance combinations and is fundamental for thermal analysis.
What are typical thermal resistance values for electronics?
CPU heat sinks: 0.1-0.5 K/W, thermal interface materials: 0.01-0.1 K/W per layer, PCB traces: 5-50 K/W, air gaps: 10-1000 K/W depending on size. Lower values indicate better heat dissipation. Junction-to-case thermal resistance is critical for component reliability.
How does contact thermal resistance affect overall performance?
Contact thermal resistance occurs at interfaces between materials due to surface roughness and air gaps. It can dominate total thermal resistance, especially in electronics. Thermal interface materials (TIMs) like thermal paste, pads, or gap fillers are used to minimize contact resistance by filling air gaps.
When should I use °F⋅s/BTU vs °F⋅hr/BTU units?
°F⋅hr/BTU is used for steady-state thermal analysis and HVAC applications where heat transfer rates are relatively slow. °F⋅s/BTU is used for transient thermal analysis, rapid thermal processes, or when dealing with high power densities where thermal time constants are important.
How accurate is the conversion between different thermal resistance units?
Our converter provides scientific precision with verified conversion factors. The difference between BTU (IT) and BTU (th) conversions is maintained for accuracy. All conversions are traceable to international standards and suitable for professional engineering applications.
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