Manufacturing Resource Planning – MRP is a software based system that integrates most aspects of a manufacturing concern, such as ordering, manufacturing, shop floor job scheduling, purchasing, packing, shipping, receiving, and inventory as a unified whole. It combines these functions in such a way that advantages and synergies of processing all information as a single system are exploited. These advantages are made possible only because of the added power over the process provided by applying computing power to the task.

Modern MRP systems (sometimes referred to as MRP-II) also close the loop, taking and feeding back measurements of important process metrics in order to make the MRP process more accurate. For example, in MRP each processing step required to manufacture an inventory item is assigned an estimated amount of time for completion. The MRP system uses this information to determine a variety of things, including how long it will take to complete orders for that item, and how long each manufacturing machine on the shop floor must be reserved. It then schedules the manufacturing of the item along with other manufacturing jobs required, allowing an estimate to be made of when an order will be completed at the time the order is first taken.

In MRP-II the actual amount of time taken for each step in the manufacturing process is measured, and used to adjust the times on record for those steps. In this way an MRP-II system continuously refines, and dramatically improves its ability to accurately schedule jobs and predict order delivery dates.