Method for assembling rotors of electrical machines, wherein each rotor has a shaft, a laminated core which is arranged on the shaft and preferably comprises a plurality of laminated core segments with magnet pockets, and magnets which are arranged in the magnet pockets, comprising at least the following steps: providing the shafts and measuring an unbalance of at least one shaft, providing laminated cores or laminated core segments and measuring an unbalance of at least one laminated core or at least one laminated core segment, providing a plurality of magnets and measuring a weight of the magnets, for each rotor to be produced, selecting a laminated core or a plurality of laminated core segments, selecting a shaft and selecting magnets, for each rotor to be produced, calculating mounting positions for the selected magnets in the magnet pockets of the selected laminated core or the selected laminated core segments and calculating a circumferential position for the selected laminated core or a circumferential position and/or axial position for the selected laminated segments on the selected shaft depending on the measured unbalance of the at least one laminated core or laminated core segment, depending on the measured weights of the respective magnets and depending on the measured unbalance of the at least one shaft, mounting the magnets in the calculated mounting positions in the magnet pockets of the laminated core or the laminated core segments and mounting the laminated core that is fitted with magnets or the laminated core segments that are fitted with magnets on the shaft in the calculated mounting position. wherein each rotor has a shaft, a laminated core which is arranged on the shaft and preferably comprises a plurality of laminated core segments with magnet pockets, and magnets which are arranged in the magnet pockets, comprising at least the following steps: providing the shafts and measuring an unbalance of at least one shaft, providing laminated cores or laminated core segments and measuring an unbalance of at least one laminated core or at least one laminated core segment, providing a plurality of magnets and measuring a weight of the magnets, for each rotor to be produced, selecting a laminated core or a plurality of laminated core segments, selecting a shaft and selecting magnets, for each rotor to be produced, calculating mounting positions for the selected magnets in the magnet pockets of the selected laminated core or the selected laminated core segments and calculating a circumferential position for the selected laminated core or a circumferential position and/or axial position for the selected laminated segments on the selected shaft depending on the measured unbalance of the at least one laminated core or laminated core segment, depending on the measured weights of the respective magnets and depending on the measured unbalance of the at least one shaft, mounting the magnets in the calculated mounting positions in the magnet pockets of the laminated core or the laminated core segments and mounting the laminated core that is fitted with magnets or the laminated core segments that are fitted with magnets on the shaft in the calculated mounting position. providing the shafts and measuring an unbalance of at least one shaft, providing laminated cores or laminated core segments and measuring an unbalance of at least one laminated core or at least one laminated core segment, providing a plurality of magnets and measuring a weight of the magnets, for each rotor to be produced, selecting a laminated core or a plurality of laminated core segments, selecting a shaft and selecting magnets, for each rotor to be produced, calculating mounting positions for the selected magnets in the magnet pockets of the selected laminated core or the selected laminated core segments and calculating a circumferential position for the selected laminated core or a circumferential position and/or axial position for the selected laminated segments on the selected shaft depending on the measured unbalance of the at least one laminated core or laminated core segment, depending on the measured weights of the respective magnets and depending on the measured unbalance of the at least one shaft, mounting the magnets in the calculated mounting positions in the magnet pockets of the laminated core or the laminated core segments and mounting the laminated core that is fitted with magnets or the laminated core segments that are fitted with magnets on the shaft in the calculated mounting position.