Not all mice have the same wheel parameters, so, in order to perform measuring with specified mouse, you must perform calibration for it for only one time. In order to perform calibration, click menu Options / Calibrate, then turn mouse upside down and roll it slowly for exactly 1 Meter, when wheel is pressed. Afterwards you can perform multiple measuring by the same way as you did with calibration. In order to stop measuring you must press Spacebar key.

The license of this software is Free Trial Software, the price is $4.60, you can free download and get a free trial.