According to Ronald Hilton, author of Textbook Managerial Accounting, "equivalent units refer to the amount of production activity that has been applied to a batch of physical units after adjusting for stage of completion". In practice it is the sum of the percentage of completion per unit. If at any given time you have 100 units completed and 200 units at 50% complete, you can report 200 equivalent units for costing purposes. When accountants need to know the costs per unit made in a specific period of time, they use equivalent units to calculate them. This concept can also be applied to direct labor and overhead costs, or “conversion costs”; a term used by the industry to indicate direct labor plus overhead