EOQ Formula: How to Calculate Economic Order Quantity In-depth

demand in units

Every business that manages inventory can benefit from measuring and following the EOQ. For example, consider a retail clothing shop that carries a line of men’s shirts. It costs the company $5 per year to hold a single shirt in inventory, and the fixed cost to place an order is $2. A perpetual inventory system is a computerized system that keeps track of the quantity of inventory on hand and updates the records as goods are purchased or sold. The basic EOQ model always assumes that you are selling just one product.

  • But there are several additional benefits to using the economic order quantity model and ordering the ideal amount of inventory at the ideal time.
  • The Gordon growth model is used to determine the intrinsic value of a stock based on a future series of dividends that grow at a constant rate.
  • Don’t leave your business future to chance or in the hands of antiquated systems.
  • After observing such outcomes, you must analyse each variable’s underlying data to isolate suspicious or unusual demand or cost drivers.
  • But in the reality of the operations, it is impossible to not cover supply and demand risks.

Economic Order Quantity Eoq carrying cost is taken as 15% to 25% of the value of average working cost, which usually amounts to 50% of the order quantity. Material acquisition costs arise on account of having to process an order. Part of the wages and operating expenses for departments such as production control, purchasing, receiving, and storage are incurred for purchasing and possessing the materials. In presence of a strategic customer, who responds optimally to discount schedules, the design of an optimal quantity discount scheme by the supplier is complex and has to be done carefully. This is particularly so when the demand at the customer is itself uncertain. An interesting effect called the “reverse bullwhip” takes place where an increase in consumer demand uncertainty actually reduces order quantity uncertainty at the supplier.

Possibility of running out of stock

The EOQ formula aims to find the optimal quantity Q to order for inventory replenishment. It is rather, Ford Whitman Harris, who developed the mathematical principle. Mr. R. H. Wilson, an industrial consultant specializing in inventory management, then used it and applied the formula to optimize inventory. Stock remainders and reorder levels – When the remaining inventory is too high or too low, you’d need to analyse why and adjust the EOQ accordingly. This is because the amount to be ordered would differ from any previous quantity. It, therefore, works best for eCommerce businesses with stable demand like clothing, consumables and beauty products.

Save Money on Inventory with EOQ – Practical Ecommerce

Save Money on Inventory with EOQ.

Posted: Mon, 17 May 2021 07:00:00 GMT [source]

The https://quick-bookkeeping.net/ model seeks to ensure that the right amount of inventory is ordered per batch. The Gordon growth model is used to determine the intrinsic value of a stock based on a future series of dividends that grow at a constant rate. The company’s reputation and profitability are always at stake if it has too much or too littleinventoryon hand.

How Is Economic Order Quantity Calculated?

Economic order quantity helps your business determine the ideal order size for any product. For example, if you run a retail, restaurant, wholesale or manufacturing business, EOQ can help you optimize order sizes to maximize profits. Once you work through EOQ, you should know the optimal number of orders per year and the ideal order size.


Additionally, seasonality may also need to be considered when ordering items. Two important categories of inventory costs are ordering costs and carrying costs. Ordering costs are costs that are incurred to obtain additional inventories, whereas carrying costs are the costs incurred to hold inventory on hand. You have to always maintain enough inventory to avoid stockout costs. This clearly states that you always have to strictly monitor your customer demand along with your inventory levels, carefully.

Limitations of Economic Order Quantity (EOQ)

The benefits of using EOQ are reduced carrying and ordering costs, improved cash flow, increased inventory turnover rate, and increased profitability. The EOQ model is used in make-to-stock environments where demand as well as ordering and storage costs are constant. If the demand for your products fluctuates, using the EOQ will give you inaccurate results. For the EOQ to work, demand should be measurably consistent year by year. Getting the sales numbers from January and assuming that you will experience the same demand for the rest of the year might lead to inventory shortages or overages down the line.


The EOQ formula is an overly simplistic solution to a very broad problem . By trying to implement it in your inventory management, you will be more aware of your own supply chain challenges. So, to find Q, multiply the demand by the ordering costs first, then multiply the product by two. Once you calculate the three variables above, apply the EOQ formula to derive the optimal order quantity of inventory. When using the EOQ formula, it’s critical to appreciate the following underlying assumptions.

Limits of the EOQ formula

Delivering this balance can be difficult.Demand forecastingis a challenge for small companies whilecarrying costscan cripple larger businesses with large inventories. Many factors have to be considered, and many decisions have to be made to gain control of inventory cost increases. The total inventory cost is the ordering cost plus the carrying cost.

  • This is the number of units the company needs for the entire year.
  • Inventory managers calculate EOQ to minimize holding costs and excess inventory.
  • Economic order quantity is a calculation companies perform that represents their ideal order size, allowing them to meet demand without overspending.
  • For example, let’s say your carrying cost is $2 per unit per year, and you average 500 units in stock.
  • Finally, if we assume all parameters are constant and stable, then we do not consider safety stocks.

Though as previously stated, the formula does not account for variable cost or demand, leading you to recalculate EOQ. This is why businesses often buy more stock than suggested by their EOQ number to not run out of stock during higher demand periods. Most business owners tend to underestimate their demand or inflate their setup costs when calculating their EOQ. This is a highly risky move as it can severely affect your EOQ number, leading to you either overspending on stock or not having enough to meet demand. Other than being aware of the amount of stock that you need to keep to satisfy demands, calculating EOQ has some other lesser-known benefits.

How to calculate the EOQ

In the Excel sheet attached here above, we are assuming the unit price to be strictly decreasing with the quantity. If it is not the case, then edit the macro EoqVD() to revert back to a naive range exploration. Download the Wilson Formula Excel here, Test it first with a few products, the most important for your business. The last two problems can be partially solved using a reorder point policy with safety stocks. In peak periods, you could “group orders” and order multiples of 600 like 1200, 1800… In low sales periods, you could order less frequently. We have another pair of shoes, a bit fancier and therefore with lower annual demand, let’s say 1000.

The overall goal of economic order quantity is to decrease spending; its formula is used to identify the greatest number of units needed to reduce buying. Calculating economic order quantity requires high school-level algebra. Once you get the variables from your inventory management system, it’s easy to plug in the numbers and calculate EOQ. When you use a robust ERP, these calculations may all be handled for you, including order costs like inventory ordering costs, holding costs and stock out costs.