Exhaust gas turbocharger with a hydrodynamic plain bearing or bearing arrangement with a hydrodynamic plain bearing, comprising a rotor, a counter-bearing part associated with the rotor and a bearing housing or a housing part, wherein a rotor bearing surface (17.1, 17.2, 17.3) of the rotor and a counter-surface of the counter-bearing part oppose each other to form a hydrodynamic plain bearing, wherein the rotor bearing part and/or the counter-bearing part, when cut along and through the axis of rotation in sectional view, form(s) a continuous bearing contour forming at least two merging contour sections (44.1 to 44.3; 53.1 to 53.3) to provide hydrodynamic load carrying capabilities in both radial and axial directions, and wherein the counter-bearing part is mounted in the bearing housing or the housing member, characterized in that between an outer contour of the counter-bearing part and the bearing housing or the housing part a circumferential gap region is formed for forming a squeezing oil film, the gap region being in spatial connection with a lubricant guide channel, and that the gap region and the continuous bearing contour of the rotor and/or of the counter-bearing part overlap at least in regions in the direction of the axis of rotation, in that the axial overlap in the direction of the axis of rotation between the counter-bearing part and the bearing housing or the housing part in the gap region for forming a squeezing oil film is dimensioned such that the ratio of an extension of the gap region in the direction of the axis of rotation to a radial clearance between the counter-bearing part and the bearing housing or the housing part is: Axial extension of the gap area 57 / radial clearance = 40 to 80. wherein a rotor bearing surface (17.1, 17.2, 17.3) of the rotor and a counter-surface of the counter-bearing part oppose each other to form a hydrodynamic plain bearing, wherein the rotor bearing part and/or the counter-bearing part, when cut along and through the axis of rotation in sectional view, form(s) a continuous bearing contour forming at least two merging contour sections (44.1 to 44.3; 53.1 to 53.3) to provide hydrodynamic load carrying capabilities in both radial and axial directions, and wherein the counter-bearing part is mounted in the bearing housing or the housing member, characterized in that between an outer contour of the counter-bearing part and the bearing housing or the housing part a circumferential gap region is formed for forming a squeezing oil film, the gap region being in spatial connection with a lubricant guide channel, and that the gap region and the continuous bearing contour of the rotor and/or of the counter-bearing part overlap at least in regions in the direction of the axis of rotation, in that the axial overlap in the direction of the axis of rotation between the counter-bearing part and the bearing housing or the housing part in the gap region for forming a squeezing oil film is dimensioned such that the ratio of an extension of the gap region in the direction of the axis of rotation to a radial clearance between the counter-bearing part and the bearing housing or the housing part is: Axial extension of the gap area 57 / radial clearance = 40 to 80.