Normal Spoilage is spoilage inherent in a particular production process. In particular, it arises even when the process is carried out in an efficient manner. The costs of normal spoilage are typically included as a component of the costs of good units manufactured because good units cannot be made without also making some defective units. For this reason, normal spoilage costs are inventoried, that is, they are included in the cost of the good units completed. The following calculations show how Mendoza Plastics accounts for the cost of the 400 units normal spoilage: