We have a blowing performance measurement test (from ANSI B175.2) we perform to calculate flow rate and velocity with. The calculation spreadsheet is attached. The inputs are: Nozzle Diameter (m) blow force (N) atmosphere temperature (°C) atmosphere pressure (hPa) atmosphere humidity (%) air stream temperature (°C) And outputs (corrected for conditions) are: Average Velocity (m/s) Peak Theoretical Velocity (m/s) Flow Rate (m3/h) I'd another output which would be corrected blow force (at standard conditions). This would be the blow force I would obtain if I took the same fan and tested it under the following conditions: atmosphere temperature = 25°C atmosphere pressure = 990 hPa atmosphere humidity = 0 % It would be easier to know which fan is most powerful (most blow force) even if you test them under different conditions. A lot of fans have different nozzle diameters and sometimes it turns out that the Flow Rate on one fan is higher but the Velocity is lower. It'd be simpler to just compare one number.