W/m²K⁴ to Btu/h-ft²R⁴ and Btu/h-ft²R⁴ to W/m²K⁴ Calculator

How to Calculate Between W/m²K⁴ and Btu/h-ft²R⁴

The W/m²K⁴ to Btu/h-ft²R⁴ and Btu/h-ft²R⁴ to W/m²K⁴ Calculator converts between watts per square meter per kelvin to the fourth (W/m²K⁴) and British thermal units per hour per square foot per Rankine to the fourth (Btu/h-ft²R⁴) for radiative heat transfer constants in SI and imperial units. The formulas are:

\( Btu/h \cdot ft^{-2} \cdot R^{-4} = W/m^2 \cdot K^{-4} \times 0.0302 \)
\( W/m^2 \cdot K^{-4} = Btu/h \cdot ft^{-2} \cdot R^{-4} \times 33.083 \)

Where the Stefan-Boltzmann constant σ in SI is 5.6704 × 10^{-8} W/m²K⁴ and in imperial is 0.1714 × 10^{-8} Btu/h-ft²R⁴.

Select the conversion direction, enter the input value, and calculate the result.

Using the W/m²K⁴ and Btu/h-ft²R⁴ Mutual Conversion Calculator

This calculator is useful for thermal radiation, heat transfer engineering, or astrophysics, such as converting emissivity or blackbody radiation constants, supporting bidirectional conversions.

Select the direction (W/m²K⁴ to Btu/h-ft²R⁴ or Btu/h-ft²R⁴ to W/m²K⁴), input the value. The calculator outputs the converted value.

Example 1: For the Stefan-Boltzmann constant 5.6704 × 10^{-8} W/m²K⁴ to Btu/h-ft²R⁴.

Direction: W/m²K⁴ to Btu/h-ft²R⁴
Input: \( 0.000000056704 \)
Calculation: \( 5.6704 \times 10^{-8} \times 0.0302 \approx 1.714 \times 10^{-9} \)
Result: \( 0.000000001714 \, \text{Btu/h-ft²R⁴} \)

Example 2: For a value of 0.1714 × 10^{-8} Btu/h-ft²R⁴ to W/m²K⁴.

Direction: Btu/h-ft²R⁴ to W/m²K⁴
Input: \( 0.000000001714 \)
Calculation: \( 0.1714 \times 10^{-8} \times 33.083 \approx 5.6704 \times 10^{-8} \)
Result: \( 0.000000056704 \, \text{W/m²K⁴} \)

Use this tool for quick bidirectional conversions in radiative heat transfer analysis.

Common FAQ

Below are frequently asked questions about W/m²K⁴ and Btu/h-ft²R⁴ conversions:

Q: What is the Stefan-Boltzmann constant?
A: σ is the constant in the Stefan-Boltzmann law for blackbody radiation: j = σ T^4.
Q: Why use these units?
A: W/m²K⁴ is SI for radiative flux per temperature^4; Btu/h-ft²R⁴ is imperial equivalent.
Q: Is the conversion factor always ≈0.0302?
A: Yes, derived from σ_SI / σ_imp where σ_SI = 5.6704 × 10^{-8}, σ_imp = 0.1714 × 10^{-8}.
Q: How accurate is this calculator?
A: It provides precise results based on the formulas, rounded to 4 decimal places.
Q: Can negative values be used?
A: No, input values must be positive; invalid inputs leave the result blank.