The invention relates to an inventory control and provides a method of managing work-in-process (WIP) inventory, comprising receiving inputs, via a user interface of a computer processing device. The inputs correspond to variables defined for modules. Each of the modules includes a set of instructions for determining and quantifying a corresponding WIP inventory driver. The method also includes executing instructions on the inputs by one or more of the modules. The inputs are applied to corresponding modules based on respective variables defined for the modules. The method further includes deriving a quantified WIP inventory resulting from execution of the instructions categorized by corresponding WIP inventory drivers.