Abstract: A device (100) and a method for determining and counting operations of a tool equipped with a mechanism that produces vibration upon operation to a predetermined value. The device comprises: a sensor (120) for detecting vibration and emitting a detection signal based upon the vibration; a mounting arrangement (116,117,118) for mounting the sensor (100) to a tool in such manner that vibration is transmittable from the tool to the sensor; a microcontroller (130) for receiving a detection signal from the sensor and determining and counting operations of said tool. The microcontroller calculates a second order derivative of a filtered detection signal and determines operation to the predetermined value based on analysis of the second order derivative signal. The microcontroller may perform the analysis by seeking a peak value of the second order derivative signal over a threshold or, alternatively, by seeking a specific shape of the second order derivative signal.