[JT118]

For your anemometer, you may also need to know the wind speed correspondent to 1 click / revolution, and make the necessary changes in the software.

I've searched on Google without success!
Is it possible to calculate it ?

If you want to know the number of clicks, you can hear the reed switch (if you hold it close to your ear) go on and off if you turn the cups, you will hear either one or two very faint ticks per revolution. If you want the other maths, this is more complex but looking at the WM pictures the dimensions look similar to the Davis instrument so the Davis settings 30 will probably work, if it is one click per revolution, I am not sure which of the other anemometers on the list are two clicks and similar dimensions but the FO setting 10 on windspeed TX config tab would be starting point.