economic order quantity

Economic order quantity (also known as the Wilson EOQ Model or simply the EOQ Model) is a model that defines the optimal quantity to order that minimizes total variable costs required to order and hold inventory.The model was originally developed by F. W. Harris in 1913, though R. H. Wilson is credited for his early in-depth analysis of the model.
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The order quantity that minimizes total inventory costs.

the optimum quantity of each product that must be ordered to balance the inventory holding costs against the order processing costs; holding costs increase with more inventory, while order processing costs decrease.