The problem of calculating parasitic capacitance between interconnects is investigated with the main theme focused on deriving approximate expressions for calculating parasitic capacitance between two crossing interconnects. The interconnects are divided into a few basic coupling regions, in such a way that the capacitance in a region can be represented by a simple expression adjusted to the results computed by an electromagnetic field solver based on a two-dimensional capacitance model. An approximate expression of the total capacitance between two crossing interconnects is obtained by summing the capacitances in all regions. In order to evaluate the accuracy of this approximation, the capacitance calculated by the attained expression is compared with the one obtained by a three-dimensional field solver, and it turns out that the error is less than 5%.