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Heat Transfer Coefficient Converter

Science

Convert heat transfer coefficient between W/m²·K, BTU/(hr·ft²·°F), and cal/(s·cm²·°C) instantly — used for HVAC, electronics cooling, and process design.

From
To
All conversionsfor 1 BTU per Hour-Square Foot-°F (BTU/(hr·ft²·°F))
Watts per Square Metre-Kelvin (W/m²·K)5.67826
BTU per Hour-Square Foot-°F (BTU/(hr·ft²·°F))1
Calories per Second-Square Centimetre-°C (cal/(s·cm²·°C))0.00013571367

What is a Heat Transfer Coefficient?

The Heat Transfer Coefficient Converter converts heat transfer coefficient between watts per square metre-Kelvin (SI), BTU per hour-square foot-°F (imperial), and calories per second-square centimetre-°C (CGS). Heat transfer coefficient measures how effectively heat moves between a surface and a fluid flowing past it — a key quantity in HVAC design, electronics cooling, and heat exchanger engineering.

Enter a value in any supported unit and the converter calculates the equivalent instantly. For related thermal quantities, see the Heat Flux Density Converter and Thermal Resistance Converter.

How to use this Heat Transfer Coefficient calculator

  1. Choose your starting unit from the source dropdown — for example, "BTU per Hour-Square Foot-°F".
  2. Enter the numeric value you want to convert in the input field.
  3. Choose your target unit from the destination dropdown — for example, "Watts per Square Metre-Kelvin (W/m²·K)".
  4. Read the converted result, which updates instantly as you type or change units.
  5. Use the swap (⇅) button if you need to reverse the conversion direction.
  6. Use the copy button to grab the result for a thermal design calculation or building energy assessment.

Formula & Methodology

The converter's base unit is watts per square metre-Kelvin (W/m²·K). Every supported unit has a fixed multiplier:

- 1 BTU/(hr·ft²·°F) ≈ 5.67826 W/(m²·K)
- 1 cal/(s·cm²·°C) = 41,840 W/(m²·K)

Any conversion follows:

Result = Input × (toBase of source unit ÷ toBase of target unit)

Worked example — converting a forced-air convective coefficient of 25 W/(m²·K) to BTU/(hr·ft²·°F):

Result = 25 × (1 ÷ 5.67826) = 4.40 BTU/(hr·ft²·°F)

This is the equivalent value you'd see on a US-convention HVAC or cooling equipment datasheet.

Frequently Asked Questions

Heat transfer coefficient measures how effectively heat transfers between a surface and a fluid (like air or water) flowing past it, per unit area and per degree of temperature difference — a higher coefficient means more efficient heat transfer, such as with forced airflow versus still air.
Multiply the BTU/(hr·ft²·°F) value by 5.67826, since one BTU per hour-square foot-°F equals approximately 5.67826 watts per square metre-Kelvin. Enter your value with 'BTU per Hour-Square Foot-°F' as the source and 'Watts per Square Metre-Kelvin (W/m²·K)' as the target to apply this automatically.
U-value (thermal transmittance) is closely related to heat transfer coefficient and uses the same units (W/m²·K), representing the overall heat transfer rate through an entire building assembly (wall, window, roof) rather than a single surface-fluid interface, but the underlying unit conversion is identical.
Heat flux density equals the heat transfer coefficient multiplied by the temperature difference (q = hΔT) — so this converter handles the coefficient itself, while the [Heat Flux Density Converter](/heat-flux-density-converter/) handles the resulting heat flow rate once you apply a specific temperature difference.
Natural convection in air typically ranges from about 2 to 25 W/(m²·K), while forced convection with fans or pumps can reach 25 to several hundred W/(m²·K) — the significant difference is why forced-air cooling is so much more effective than passive cooling for high heat-load applications.
Heat transfer coefficient (W/m²·K) is the inverse of thermal resistance per unit area — a high heat transfer coefficient corresponds to low thermal resistance, and vice versa. See the [Thermal Resistance Converter](/thermal-resistance-converter/) for that related, inversely-scaled quantity.
Unlike thermal conductivity (a fixed material property), convective heat transfer coefficient depends on fluid velocity, turbulence, surface geometry, and fluid properties, making it typically determined experimentally or through empirical correlations rather than calculated from first principles alone.
HVAC engineering (building envelope U-values), electronics cooling (heatsink and fan performance specifications), process engineering (heat exchanger design), and automotive engineering (radiator and cooling system design) all routinely require heat transfer coefficient data, often needing conversion between unit systems.
Yes, substantially — water's much higher thermal conductivity and heat capacity give it heat transfer coefficients often an order of magnitude or more higher than air under comparable flow conditions, which is why liquid cooling systems are so much more effective than air cooling for high heat-load applications.
It's typically determined by measuring the heat flux through a surface (via a known power input) alongside the temperature difference between the surface and the surrounding fluid, then calculating h = q ÷ ΔT from those measurements.
Also known as
heat transfer coefficient converterw/m2k to btu/hr ft2 f converterconvective heat transfer coefficient unitsfilm coefficient converteru value converter