Cumulative lead time is the time spent to complete a task from scratch. In a manufacturing environment, the cumulative lead time clock starts ticking after raw material purchase and ends at product shipment, with fabrication (cutting, molding, welding, finishing, etc.), assembling, testing, and packaging serving as interims. Within an industry setup, cumulative lead time is the longest accounted time since it applies only if the required components or raw materials are not in stock.