This paper shows that the mass inventory for steam turbines can be distributed between high-pressure (HP) and low-pressure (LP) turbines such that the global performance of the power plant is maximal. This is demonstrated for two design classes. For an HP turbine in series with an LP turbine, the optimal intermediate pressure (IP) is a geometric average of HP and LP. The total mass is distributed in a balanced way based on the total mass of turbines. For a train consisting of many turbines expanding the steam at nearly constant temperature, the pressure ratio between consecutive IP should be constant, and more mass should be distributed at HPs. This approach to discovering the configuration of the power plant should be used in conjunction with classical approaches that account for vibration, centrifugal force and blade length. Copyright (C) 2009 John Wiley & Sons, Ltd.