Electromagnetic metamaterial emitters and absorbers rely on a variety of electromagnetic resonances (ie, polaritons) with different metallic nano/microstructured patterns such as strips, squares, circular disks, crosses, and square rings. A unique mechanism exists for different structures with various metallic patterns due to the similarity of the configuration. Thus, we explore a unified model which can greatly simplify the design process of these nano/microstructures. In the present study, an inductor-capacitor (LC) circuit model is used to predict the magnetic resonance conditions or magnetic polaritons (MPs) for metamaterial emitters and absorbers with different shapes. By suitably adjusting some of the parameters, the LC circuit model can reasonably predict the resonance conditions for published experimental results as well as rigorous electromagnetic wave simulations for the fundamental MP mode regardless of the shape of the metallic patterns. This study may facilitate the initial design of metamaterial emitters and absorbers.