Stator for an electric machine comprising a cylindrical stator pack, on the inner surface of which is formed a plurality of uniformly distributed slots, each slot having a radially inward oriented opening and covered with electric insulation, wherein double-layer windings are laid in the slots, wherein the double-layer windings are composed of double-arm sections, each double-arm section comprising a covering elementary double-arm section and a covered elementary double-arm section, wherein • the covering elementary double-arm section is made of a first wire (85, 86) with rectangular cross-section shaped as an open hair pin having a first and a second arm, wherein the cross-section of the first wire (85, 86) is constant along its entire length, wherein • the covered elementary double-arm section is made of a second wire (95, 96) with rectangular cross-section shaped as an open hair pin having a first and a second arm, wherein the cross-section of the second wire (95, 96) is constant along its entire length, wherein • the covering elementary double-arm section covers the covered elementary double-arm section in a manner that the first arm of the covering elementary double-arm section covers the first arm of the covered elementary double-arm section in radial inward direction and • the second arm of the covering elementary double-arm section covers the second arm of the covered elementary double-arm section in radial outward direction, so that the first and the second arm (962, 952) of the covered elementary double-arm section are radially disposed between the first and the second arm (862, 852) of the covering elementary double-arm section, wherein • in order to form the double-layer windings of the stator, the double-arm sections are laid in the slots in a manner that in each slot the first arm of the covering elementary double-arm section and the second arm of the covered elementary double-arm section of one of the double-arm sections are disposed radially outward, while the second arm of the covered elementary double-arm section and the second arm of the covering elementary double-arm section of one other of the double-arm sections are disposed radially inward within the same slot, characterised in that • all slots have a substantially identical rectangular cross-section in a plane perpendicular to the axis of rotation of the electric machine, wherein • the rectangular cross-section of the first wire (85, 86) and the second wire (95, 96) substantially correspond to the width of the slots, wherein • the cross-sectional area of the first wire (85, 86) within each slot is uniformly reduced in redial direction with respect to the cross-sectional area of the second wire (95, 96) in order to reduce the electric losses in the stator windings. • the covering elementary double-arm section is made of a first wire (85, 86) with rectangular cross-section shaped as an open hair pin having a first and a second arm, wherein the cross-section of the first wire (85, 86) is constant along its entire length, wherein • the covered elementary double-arm section is made of a second wire (95, 96) with rectangular cross-section shaped as an open hair pin having a first and a second arm, wherein the cross-section of the second wire (95, 96) is constant along its entire length, wherein • the covering elementary double-arm section covers the covered elementary double-arm section in a manner that the first arm of the covering elementary double-arm section covers the first arm of the covered elementary double-arm section in radial inward direction and • the second arm of the covering elementary double-arm section covers the second arm of the covered elementary double-arm section in radial outward direction, so that the first and the second arm (962, 952) of the covered elementary double-arm section are radially disposed between the first and the second arm (862, 852) of the covering elementary double-arm section, wherein • in order to form the double-layer windings of the stator, the double-arm sections are laid in the slots in a manner that in each slot the first arm of the covering elementary double-arm section and the second arm of the covered elementary double-arm section of one of the double-arm sections are disposed radially outward, while the second arm of the covered elementary double-arm section and the second arm of the covering elementary double-arm section of one other of the double-arm sections are disposed radially inward within the same slot, characterised in that • all slots have a substantially identical rectangular cross-section in a plane perpendicular to the axis of rotation of the electric machine, wherein • the rectangular cross-section of the first wire (85, 86) and the second wire (95, 96) substantially correspond to the width of the slots, wherein • the cross-sectional area of the first wire (85, 86) within each slot is uniformly reduced in redial direction with respect to the cross-sectional area of the second wire (95, 96) in order to reduce the electric losses in the stator windings.