Convert Watt per square metre to International table BTU per hour per square foot
Convert Watt per square metre (W/m²) to International table BTU per hour per square foot (BTU(IT)/(h·ft²)) instantly and accurately.
Conversion Formula
BTU(IT)/(h·ft²) = W/m² × 0.3169983306
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 hour per square foot
The international table BTU per hour per square foot (BTU(IT)/(h·ft²)) equals 1055.05585262/(3600×0.09290304) ≈ 3.15459 W/m². The standard US heat flux unit in ASHRAE, ASTM, and building codes for thermal resistance (R-value), boiler ratings, and heat exchanger design. 1 BTU(IT)/(h·ft²) ≈ 3.15459 W/m².
Quick Reference Table
| Watt per square metre (W/m²) | International table BTU per hour per square foot (BTU(IT)/(h·ft²)) |
|---|---|
| 1 W/m² | 0.316998 BTU(IT)/(h·ft²) |
| 2 W/m² | 0.633997 BTU(IT)/(h·ft²) |
| 5 W/m² | 1.58499 BTU(IT)/(h·ft²) |
| 10 W/m² | 3.16998 BTU(IT)/(h·ft²) |
| 25 W/m² | 7.92496 BTU(IT)/(h·ft²) |
| 50 W/m² | 15.8499 BTU(IT)/(h·ft²) |
| 100 W/m² | 31.6998 BTU(IT)/(h·ft²) |