1. A production planning system, comprising: a graphical user interface configured to receive values for one or more capacity attributes characterizing a manufacturing line configured to produce one or more products; at least one computing engine configured to compute one or more inventory investment amounts based upon the received one or more capacity attribute values and needed to cover expected demand and expected demand uncertainty for the one or more products over an exposure period with a target service level; wherein the graphical user interface is configured to display the one or more computed inventory investment amounts.