A statistical inventory management system may optimize inventory investment using historical usage and/or consumption of an inventory component by determining one or more target inventory levels (e.g., replenishment levels). Historical usage data may be summed for a plurality of at least partially non-overlapping time periods that may be each equal in duration to a supplier lead-time period for the component to create lead-time usage data. The lead-time usage data may be utilized to more accurately determine future inventory levels (e.g., target inventory levels) because the lead-time usage data may have a reduced variance compared to, for example, day-to-day usage. The inventory management system may be employable by a computing system having a display module (e.g., GUI) that allows a user to receive at least one graphical representation indicative of at least one target inventory level of at least one inventory component (e.g., by selectively interacting with the display module).