Convert Watt per square metre to International table BTU per second per square foot
Convert Watt per square metre (W/m²) to International table BTU per second per square foot (BTU(IT)/(s·ft²)) instantly and accurately.
Conversion Formula
BTU(IT)/(s·ft²) = W/m² × 8.805509184e-5
About Watt per square metre
The watt per square metre (W/m²) is the SI coherent unit for heat flux density and irradiance. Solar irradiance at Earth's surface ≈ 1000 W/m²; solar constant ≈ 1361 W/m²; human skin radiative emission ≈ 100 W/m²; global average geothermal flux ≈ 0.087 W/m². Referenced in ISO 80000-4. 1 W/m² = 1 J/(s·m²) = 10⁻³ kW/m².
About International table BTU per second per square foot
The international table BTU per second per square foot (BTU(IT)/(s·ft²)) equals 1055.05585262/0.09290304 ≈ 11357 W/m² (= 3600 × BTU(IT)/(h·ft²)). Used for extreme heat flux: atmospheric re-entry aerodynamic heating, solid rocket nozzle throat, and nuclear reactor thermal hydraulics design. 1 BTU(IT)/(s·ft²) ≈ 11357 W/m².
Quick Reference Table
| Watt per square metre (W/m²) | International table BTU per second per square foot (BTU(IT)/(s·ft²)) |
|---|---|
| 1 W/m² | 8.806 × 10-5 BTU(IT)/(s·ft²) |
| 2 W/m² | 0.00017611 BTU(IT)/(s·ft²) |
| 5 W/m² | 0.000440275 BTU(IT)/(s·ft²) |
| 10 W/m² | 0.000880551 BTU(IT)/(s·ft²) |
| 25 W/m² | 0.00220138 BTU(IT)/(s·ft²) |
| 50 W/m² | 0.00440275 BTU(IT)/(s·ft²) |
| 100 W/m² | 0.00880551 BTU(IT)/(s·ft²) |