Convert Square feet per hour to Square millimetres per second
Convert Square feet per hour (ft²/h) to Square millimetres per second (mm²/s) instantly and accurately.
Conversion Formula
mm²/s = ft²/h × 25.8064
About Square feet per hour
The square foot per hour (ft²/h) equals 0.3048²/3600 ≈ 2.581 × 10⁻⁵ m²/s. It is the standard US unit for thermal diffusivity in the BTU-ft-h system, used alongside heat-transfer and mass-transfer calculations. Air at 20 °C ≈ 0.573 ft²/h; water at 20 °C ≈ 0.0096 ft²/h. 1 ft²/h ≈ 25.81 cSt.
About Square millimetres per second
The square millimetre per second (mm²/s) equals 10⁻⁶ m²/s, numerically identical to 1 centistoke (cSt). It is the preferred SI-consistent expression: ISO 3104, DIN 51562, and ASTM viscosity standards all use mm²/s interchangeably with cSt. Water at 20 °C ≈ 1.004 mm²/s; SAE 10W-30 at 100 °C: 9.3-12.5 mm²/s. 1 mm²/s = 1 cSt.
Quick Reference Table
| Square feet per hour (ft²/h) | Square millimetres per second (mm²/s) |
|---|---|
| 1 ft²/h | 25.8064 mm²/s |
| 2 ft²/h | 51.6128 mm²/s |
| 5 ft²/h | 129.032 mm²/s |
| 10 ft²/h | 258.064 mm²/s |
| 25 ft²/h | 645.16 mm²/s |
| 50 ft²/h | 1290.32 mm²/s |
| 100 ft²/h | 2580.64 mm²/s |