In your case you need to know how many turns / sec you get for a certain windspeed, say in m/s. Ideally you have the manufacturer specification for your sensor. Otherwise you have to use an anemometer for calibration. If you don't have access to one then you build what is called a ping-pong ball anemometer (see e.g. http://www.education.com/science-fair/article/earth-science_building-anemometer/. Otherwise you set the coeff to 30 and just report the rpm of your sensor.
In your case you need to know how many turns / sec you get for a certain windspeed, say in m/s. Ideally you have the manufacturer specification for your sensor. Otherwise you have to use an anemometer for calibration. If you don't have access to one then you build what is called a ping-pong ball anemometer (see e.g. http://www.education.com/science-fair/article/earth-science_building-anemometer/. Otherwise you set the coeff to 30 and just report the rpm of your sensor.