Convert International table BTU per hour per square foot to Watt per square millimetre
Convert International table BTU per hour per square foot (BTU(IT)/(h·ft²)) to Watt per square millimetre (W/mm²) instantly and accurately.
Conversion Formula
W/mm² = BTU(IT)/(h·ft²) × 3.154590745e-6
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.
About Watt per square millimetre
The watt per square millimetre (W/mm²) equals exactly 10⁶ W/m². Used in high-power laser material processing - cutting, welding, and additive manufacturing - and electron beam applications. A 1 kW laser focused to 1 mm² achieves 1 W/mm². Numerically equal to MW/m². 1 W/mm² = 10⁶ W/m² = 100 W/cm².
Quick Reference Table
| International table BTU per hour per square foot (BTU(IT)/(h·ft²)) | Watt per square millimetre (W/mm²) |
|---|---|
| 1 BTU(IT)/(h·ft²) | 3.155 × 10-6 W/mm² |
| 2 BTU(IT)/(h·ft²) | 6.309 × 10-6 W/mm² |
| 5 BTU(IT)/(h·ft²) | 1.577 × 10-5 W/mm² |
| 10 BTU(IT)/(h·ft²) | 3.155 × 10-5 W/mm² |
| 25 BTU(IT)/(h·ft²) | 7.886 × 10-5 W/mm² |
| 50 BTU(IT)/(h·ft²) | 0.00015773 W/mm² |
| 100 BTU(IT)/(h·ft²) | 0.000315459 W/mm² |