Effective use of machines and headcounts is essential in manufacturing for high return of investment from expensive resources in today’s competitive business environment. It is thus crucial to establish optimal man-machine ratio to gain high resource utilization and output. In this paper, we discuss the deficiency of traditional static methods and how simulation can be applied to overcome these deficiency in order to establish optimal man-machine ratio. In addition, we discuss using simulation to facilitate decision making on headcount movement from non-constraint tool to constraint tool to boost productivity of constraint tool, and ultimately increase overall factory output.