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 ≈2.581 × 10⁻⁵ m²/s and is the dominant unit in US engineering practice for thermal diffusivity of building materials and industrial insulation. ASHRAE handbooks, Perry's Chemical Engineers' Handbook, and NFPA fire-resistance tables all list diffusivity in ft²/h. Steel: ≈0.4-0.5 ft²/h; concrete: ≈0.023 ft²/h; mineral wool: ≈0.005 ft²/h. 1 ft²/h = 0.09290304/3600 m²/s.
About Square millimetres per second
The square millimetre per second (mm²/s) equals 1 × 10⁻⁶ m²/s and is the standard unit in materials engineering and the laser-flash diffusivity method (ASTM E1461, ISO 22007-4). Metals span roughly 2-180 mm²/s; polymers 0.07-0.2 mm²/s; ceramics 0.3-10 mm²/s. Numerically identical to the kinematic viscosity unit (cSt) in SI context. 1 mm²/s = 1 × 10⁻⁶ m²/s.
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 |