Additive Manufacturing (AM) is an emerging manufacturing method by which Computer-Aided Design (CAD) models are directly made into products and structures. Layers of material, such as polymers, metals, ceramics, composites, and rubber, are formed and joined layer by layer to construct the product. Since its introduction in the 1980s, the technology has evolved from the confines of Rapid Prototyping (RP) to the realm of manufacturing. Nowadays, with contributions from material scientists, software, and hardware engineers, the technology can construct fully functional products. AM allows engineers to explore innovative design ideas without the restrictions imposed by traditional manufacturing methods. It has been utilized in many industry subsectors including aerospace, automotive, machinery, electronics, and medical products. However, the cost is an important factor in utilizing this technology. A review of the models for calculating cost of products built using AM technology has shown that each of these cost models are focused on specific AM systems. The most comprehensive of which does not account for several major elements including AM material depreciation, process control, final product testing, and the material consumed during construction and post-processing stages. These are critical cost elements which have substantial contribution to overall manufacturing cost. A mathematical cost model to include all these ignored cost elements has been proposed in this study. Model formulation is provided to include all the pre-processing, processing, and post-processing costs. For illustration, numerical example from industry is provided with which the developed formulation is applied to. The formulation described in this research provides a comprehensive cost model that can be applied to all AM systems.