Disclosed is technology for evaluating the performance of various conducting structures in an integrated circuit. A three-dimensional circuit representation of a circuit design is provided. The three-dimensional circuit representation includes a plurality of conducting structures including a first conducting structure which has a length L. A plurality of longitudinally adjacent volume elements is identified in the conducting structure. A width Wn and a height Hn are estimated for each volume element n in the conducting structure. Furthermore, the local resistivity ρn for each volume element n is estimated based on a function that is dependent upon the length L of the conducting structure and the width Wn and height Hn of the volume element n. The resistance of a conducting structure is estimated in dependence upon the resistivity ρn for each of the volume elements n in the plurality of volume elements in the conducting structure.