A computer method or corresponding system for optimally balancing a rotor assembly. The computer system defines a theoretical centerline based on a mathematical model of the rotor assembly. For each disc or component of the rotor assembly, the invention system calculates rotor blade or bolt and washer distribution, based on calculated centerline deviations and angular locations of the discs and effective weights of rotor blade or bolt-and-washer sets. The rotor blade or bolt-and-washer distribution provides locations for placement of the rotor blades or bolts-and-washers so as to offset the centerline deviations and thus correct imbalance of the rotor assembly.