A mobile machine tool (10), namely a manually-operated machine tool or semi-stationary machine tool, for machining a workpiece (W), wherein the machine tool has a plate-like guide element (30) with a guide surface (32) for guiding the machine tool on the workpiece (W) or the workpiece (W) on the machine tool, wherein the machine tool has a drive unit (11) with a drive motor (13) for driving a tool holder (14) arranged on the drive unit (11), wherein the drive unit (11) is, by means of a bearing arrangement (35), mounted adjustably on the guide element (30) in order to adjust at least two adjustment positions (S0, S1, S2) of the tool holder (14) relative to the guide surface (32) in which a work tool (15) arranged on the tool holder (14), penetrates into the workpiece (W), to different penetration depths. The machine tool (10) is provided with a height measuring device (95) for detecting a height (H) of the workpiece (W), wherein the height corresponds to a distance between an upper side (WO) of the workpiece which is to be penetrated by the work tool (15) and a workpiece underside (WU) of the workpiece (W) opposite the upper side of the workpiece (W).