The amount of time required for a product to be available for use from the time it is ordered. Lead time usually includes purchase order processing time, supplier processing time, in transit time, receiving, inspection, and any prepack times. However, based on the way many inventory systems work, there may be problems incorporating internal factors such as post-receipt processing in Lead-time, so in many systems, the lead time just represents the period of time from which the item is ordered to the time it arrives at recipient's dock.