Convert Watts per Square Meter per Kelvin to Btu (th) per Hour per Square Foot per °F
Watt per Square Meter per Kelvin (W/(m²·K)) to Btu (th) per Hour per Square Foot per °F (Btu(th)/(h·ft²·°F)) heat transfer coefficient conversion — enter any value below to get an instant result, or use the table for common values.
Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.
Result
1 W/(m²·K) = 0.17622804 Btu(th)/(h·ft²·°F)
1 Watt per Square Meter per Kelvin = 0.17622804 Btu (th) per Hour per Square Foot per °F
1 Btu (th) per Hour per Square Foot per °F = 5.6744659 Watts per Square Meter per Kelvin
1 W/(m²·K) in every supported unit
Conversion chart: Watt per Square Meter per Kelvin to Btu (th) per Hour per Square Foot per °F
Conversion table
| Watt per Square Meter per Kelvin (W/(m²·K)) | Btu (th) per Hour per Square Foot per °F (Btu(th)/(h·ft²·°F)) |
|---|---|
| 0.01 W/(m²·K) | 0.0017622804 Btu(th)/(h·ft²·°F) |
| 0.1 W/(m²·K) | 0.017622804 Btu(th)/(h·ft²·°F) |
| 1 W/(m²·K) | 0.17622804 Btu(th)/(h·ft²·°F) |
| 2 W/(m²·K) | 0.35245608 Btu(th)/(h·ft²·°F) |
| 3 W/(m²·K) | 0.52868412 Btu(th)/(h·ft²·°F) |
| 5 W/(m²·K) | 0.8811402 Btu(th)/(h·ft²·°F) |
| 10 W/(m²·K) | 1.7622804 Btu(th)/(h·ft²·°F) |
| 20 W/(m²·K) | 3.5245608 Btu(th)/(h·ft²·°F) |
| 50 W/(m²·K) | 8.811402 Btu(th)/(h·ft²·°F) |
| 100 W/(m²·K) | 17.622804 Btu(th)/(h·ft²·°F) |
| 1000 W/(m²·K) | 176.22804 Btu(th)/(h·ft²·°F) |
Watt per Square Meter per Kelvin (W/(m²·K))
Definition: The SI derived unit of heat transfer coefficient — the watts of heat power crossing one square meter of surface per kelvin of temperature difference between the surface and the fluid touching it.
History: Formed directly from the watt, square meter, and kelvin once all three were standardized as SI units, giving heat-transfer engineering a coherent film-coefficient unit.
Current use: The standard unit in convective heat-transfer engineering worldwide, rating how effectively a fluid (air, water, oil) carries heat away from or into a surface.
Btu (th) per Hour per Square Foot per °F (Btu(th)/(h·ft²·°F))
Definition: Nearly identical to the IT-Btu version, using the slightly different thermochemical Btu definition instead of the International Table Btu.
History: Reflects the same historical split between the International Table Btu and the thermochemical Btu found throughout US heat-engineering units.
Current use: Occasionally appears in thermochemistry-oriented US engineering references that specify the thermochemical Btu explicitly.
Supported Units
| Unit | Symbol | In W/(m²·K) |
|---|---|---|
| Watt per Square Meter per Kelvin | W/(m²·K) | 1 W/(m²·K) |
| Kilocalorie (IT) per Hour per Square Meter per °C | kcal/(h·m²·°C) | 1.163 W/(m²·K) |
| Calorie (IT) per Second per Square Centimeter per °C | cal/(s·cm²·°C) | 41868 W/(m²·K) |
| Btu (IT) per Hour per Square Foot per °F | Btu/(h·ft²·°F) | 5.6782633 W/(m²·K) |
| Btu (th) per Hour per Square Foot per °F | Btu(th)/(h·ft²·°F) | 5.6744659 W/(m²·K) |
| Btu (IT) per Second per Square Foot per °F | Btu/(s·ft²·°F) | 20441.748 W/(m²·K) |
| Kilocalorie (IT) per Hour per Square Foot per °C | kcal/(h·ft²·°C) | 12.518428 W/(m²·K) |
About These Parameters
- Value
- The heat transfer coefficient value you want to convert, expressed in the "From" unit. Accepts decimals.
- From Unit
- The unit your input value is currently measured in — a physics reference's W/(m²·K), or a US HVAC design guide's Btu/(h·ft²·°F).
- To Unit
- The unit you want the result converted into. Use the swap button to flip From and To instantly.
How Heat Transfer Coefficient Conversion Works
The Formula
Every unit here is defined by a fixed multiplier relative to watts per square meter per kelvin. To convert a value from one unit to another:
result = value × (factor of "From" unit ÷ factor of "To" unit)
For Watt per Square Meter per Kelvin → Btu (th) per Hour per Square Foot per °F: multiply by 0.17622804. For example, 1 W/(m²·K) × 0.17622804 = 0.17622804 Btu(th)/(h·ft²·°F).
Newton's Law of Cooling
The heat transfer coefficient (h) is the proportionality constant in Newton's law of cooling: heat flux = h × (surface temperature − fluid temperature). A larger h means heat moves faster for the same temperature difference — still air might have h around 5-25 W/(m²·K), while forced water flow can reach several thousand, which is exactly why liquid cooling systems outperform air cooling by such a wide margin in high-power electronics and industrial equipment.
Convection vs. Conduction
This converter's units describe convective heat transfer — heat carried by a moving fluid touching a surface. That's a different physical mechanism from conduction, covered by the site's Thermal Conductivity Converter, which describes heat moving THROUGH a solid material. A complete heat-transfer calculation (like sizing a heat exchanger or predicting a building's heat loss) typically needs both: conduction through the walls or tube material, and convection at each fluid-contacted surface.
Example
A heat transfer coefficient of 1 W/(m²·K) equals 0.17622804 Btu(th)/(h·ft²·°F). For scale, natural (unforced) air convection typically gives coefficients around 5-25 W/(m²·K), forced air convection (a fan) around 10-200 W/(m²·K), and forced water convection can reach 500-10,000 W/(m²·K) or higher.
Frequently Asked Questions
How many Btu (th) per Hour per Square Foot per °F are in 1 Watt per Square Meter per Kelvin?
1 Watt per Square Meter per Kelvin (W/(m²·K)) equals exactly 0.17622804 Btu (th) per Hour per Square Foot per °F (Btu(th)/(h·ft²·°F)).
What's the difference between this and the Thermal Resistance Converter?
Heat transfer coefficient (this page) is a per-area rate — watts per square meter per degree. Thermal Resistance (a separate converter on this site) is a single-point figure without an area term — kelvin per watt — more suited to whole components like an electronics package. They're related but describe convection at a surface versus overall resistance of an object.
Why is water so much better than air at heat transfer?
Water has both a much higher density and specific heat capacity than air, and moving water carries far more thermal energy per unit volume than moving air for the same temperature rise — which translates directly into a much higher convective heat transfer coefficient, often 20-100 times greater for comparable flow conditions.
How accurate are these conversions?
Every conversion factor used here is the exact, internationally recognized relationship between the underlying power, area, and temperature units — results are limited only by floating-point display precision, not by rounded conversion constants.