Equivalent Units of Conversion Costs The Rolling Department of Kraus Steel Company had 200 tons in beginning work in process inventory (60% complete) on October 1. During October, 3,900 tons were completed. The ending work in process inventory on October 31 was 300 tons (25% complete). What are the total equivalent units for conversion costs? 4,000 X units Feedback Check My W Are you determining the equivalent units of materials added or of conversion of materials? When would materials typically be added in the process? When would conversion of these materials take place? Recall the definition of work in process.