When the direct current (DC) metallised thin film capacitor is fully charged the electromagnetic fields can be considered to have reached a steady state in which the governing equation is Laplace’s equation. It is the computational analysis of the electrostatic state that is considered in this paper. The capacitor is modelled as a stack made up of infinitesimally thin layers of metal on polymer. An integral equation method is developed and applied to the problem of modelling the electric field. The method is applied to a typical capacitor structure and encouraging results are obtained.