Economic order quantity is the level of inventory that minimizes total inventory holding costs and ordering costs. It is one of the oldest classical production scheduling models. The framework used to determine this order quantity is also known as Wilson EOQ Model or Wilson Formula. The model was developed by Ford W. Harris in 1913, but R. H. Wilson, a consultant who applied it extensively, is given credit for his in-depth analysis.
EOQ applies only when demand for a product is constant over the year and each new order is delivered in full when inventory reaches zero.