7.7
Economic Order Quantity
Commercial distributors often face a trade-off between ordering frequency and inventory holding. Ordering too often inflates administrative costs, whi…
CleanPro, a commercial cleaning supplies distributor, faces rising inventory costs due to inefficient ordering practices.
Frequent small orders increase ordering expenses, while large bulk orders increase storage and insurance costs.
As a result, CleanPro faces higher overall inventory costs and decreased operational efficiency.
The company has decided to apply the Economic Order Quantity model or EOQ to address the issue.
This model determines the optimal order quantity that minimizes total inventory costs, including ordering and holding costs.
EOQ is calculated as the square root of two times the annual demand, multiplied by the ordering cost, divided by the annual holding cost per unit.
CleanPro sells ten thousand units of a product each year.
The cost of placing an order is one hundred dollars, and the annual holding cost per unit is two dollars.
Using the EOQ formula, the optimal order quantity is calculated to be one thousand units.
EOQ is most effective when demand is consistent, lead times are constant, and cost factors remain stable.
View the full transcript and gain access to JoVE Business videos
Q1: What problem does the Economic Order Quantity model solve for inventory management?
EOQ addresses the cost trade-off between frequent small orders and large bulk purchases. Frequent orders inflate administrative expenses, while bulk orders increase storage, insurance, and capital tied up in inventory. EOQ identifies the optimal order quantity that minimizes combined ordering and holding costs, improving operational efficiency and reducing overall inventory expenses.
Q2: How is Economic Order Quantity calculated?
EOQ equals the square root of twice the annual demand multiplied by the ordering cost, divided by the annual holding cost per unit. For example, if annual demand is 10,000 units, ordering cost is $100, and holding cost per unit is $2, the EOQ formula yields an optimal order quantity of 1,000 units that minimizes total inventory costs.
Q3: What assumptions must hold for EOQ to be effective?
EOQ works best when demand is consistent, lead times remain constant, and cost factors stay stable. However, real business environments often experience seasonal demand fluctuations, bulk discount opportunities, or supply chain disruptions. When these assumptions don't hold, EOQ should be adapted or supplemented with other inventory models to maintain accuracy.
Q4: How do ordering costs and holding costs affect the optimal order quantity?
Ordering costs and holding costs create opposing pressures on order quantity. Higher ordering costs push toward larger orders to reduce frequency, while higher holding costs push toward smaller, more frequent orders. EOQ mathematically balances these competing factors to find the order size that minimizes their combined impact on total inventory expenses.
Q5: Why might Just-in-Time inventory be considered an alternative to EOQ?
Just-in-Time inventory systems minimize holding costs by receiving goods only when needed, contrasting with EOQ's fixed order quantity approach. While EOQ assumes stable demand and costs, just in time inventory works best with reliable suppliers and predictable demand. Businesses may use just in time inventory when holding costs are extremely high or supply chain reliability is strong.
Q6: Should safety stock be used alongside EOQ calculations?
Yes, incorporating safety stock is often necessary even when using EOQ as a foundation. Safety stock buffers against delivery delays and demand variability that EOQ's assumptions don't account for. This additional inventory protects against stockouts when actual conditions deviate from the stable demand and lead times that EOQ presumes.
Q7: How can bulk discounts affect the use of EOQ in practice?
Bulk discounts complicate EOQ because suppliers often offer lower per-unit prices for larger orders, creating incentives to order beyond the calculated EOQ. When significant discounts are available, businesses must compare the savings from bulk pricing against the increased holding costs. EOQ should be adapted or supplemented with quantity discount models to make optimal ordering decisions.