As industrial and commercial demand for thin, small-footprint energy storage devices increases (e.g., for wearable electronics, wireless sensor networks, etc.), it is essential to develop theoretical descriptions for those devices in order to make effective design choices. Of particular interest are porous interdigitated electrodes, which can function as supercapacitors but which are nontrivial to analyze due to their unique geometry. In this paper, we develop a purely mathematical model to determine the dependence of a cell's capacitance and/or resistance on electrode height, width, and spacing, and electrolyte layer height. We then extend this model to incorporate effects from the porous nature of the electrodes, and show that in many cases of interest, the system can be described using a simple equivalent circuit. (C) 2017 The Electrochemical Society. All rights reserved.