It is shown that a working process of rock excavation realized by an open-pit front-shovel excavator is characterized by an increased power intensity due to counteraction of its main actuating mechanisms (lifting and thrusting), whose operational parameters have to be properly matched during their joint action to provide more efficient excavation. A computational experiment allowed to determine an actual work of lifting and thrusting forces immediately involved in developing an excavated face. It was further established that power inputs depend on the bucket position relative to the working area of an excavator, and such regions of that area where those inputs are higher were determined. Differentiated calculation of the inputs was carried out, based on the type of a conducted operation – power inputs originating from excavating, from counteraction of the main mechanisms, and from lifting operational equipment parts and rock. The power intensity of excavation was estimated for various regions of the workspace of the excavator. The proposed method for calculating the power inputs of rock excavation using the operational equipment of an open-pit excavator would allow to determine an energy characteristic of the excavator for specific mining and technical conditions of operation.