The article presents a method for calculating the accuracy of large-span metal rod systems and its mathematical model. The method takes into account the connectivity of hinged-rod metal shells, the technology of their construction and the gaps in the bolted joints. The latter are caused by the the center of the hole deviating from its designed position and by the actual shape of the holes for the bolts designing from the nominal form. An example of calculating the hinged-rod shell with polybolted seams on the lining is described in the article. It is also shown how to use the proposed methodology for calculating the accuracy of hinged-rod metal shells in general combined with the previously proposed method for generating hinged-rod systems. Consequently, the proposed method for calculating the accuracy of large-span metal rod systemscan be used for determining the deviations of both the whole hinge-rod system and its individual elements. in the method presented in this papercan be used when calculating the accuracy of a variety of joint-core multiple systems, made from metal, e.g., support tower chimneys, radio telescopes, cooling towers, antennas and similar structures.