What Is Inventory Turnover?

Inventory turnover is a ratio showing how many times a company has sold and replaced inventory during a given period. A company can then divide the days in the period by the inventory turnover formula to calculate the days it takes to sell the inventory on hand. Calculating inventory turnover can help businesses make better decisions on pricing, manufacturing, marketing and purchasing new inventory.

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Inventory Turnover Formula and Calculation

﻿\begin{aligned} &\text{Inventory Turnover} = \frac{ \text {Sales} }{ \text {Average Inventory} } \\ &\textbf{where:} \\ &\text {Average Inventory} = ( \text {BI} - \text {Ending Inventory} ) \div 2 \\ &\text {BI} = \text {Beginning Inventory} \\ \end{aligned}﻿

Companies calculate inventory turnover by:

• Calculating the average inventory, which is done by dividing the sum of beginning inventory and ending inventory by two
• Dividing sales by average inventory

An alternative method includes using the cost of goods sold (COGS) instead of sales. Analysts divide COGS by average inventory instead of sales for greater accuracy in the inventory turnover calculation because sales include a markup over cost. Dividing sales by average inventory inflates inventory turnover. In both situations, average inventory is used to help remove seasonality effects.

Key Takeaways

• Inventory turnover shows how many times a company has sold and replaced inventory during a given period.
• This helps businesses make better decisions on pricing, manufacturing, marketing, and purchasing new inventory.
• A low turnover implies weak sales and possibly excess inventory, while a high ratio implies either strong sales or insufficient inventory.

What Inventory Turnover Measures

Inventory turnover measures how fast a company sells inventory and how analysts compare it to industry averages. A low turnover implies weak sales and possibly excess inventory, also known as overstocking. It may indicate a problem with the goods being offered for sale or be a result of too little marketing.

A high ratio implies either strong sales or insufficient inventory. The former is desirable while the latter could lead to lost business. Sometimes a low inventory turnover rate is a good thing, such as when prices are expected to rise (inventory pre-positioned to meet fast-rising demand) or when shortages are anticipated.

The speed at which a company can sell inventory is a critical measure of business performance. Retailers that move inventory out faster tend to outperform. The longer an item is held, the higher its holding cost will be, and the fewer reason consumers will have to return to the shop for new items.

A good example can be seen in the fast fashion business (H&M, Zara, for example). Such companies limit runs and replace depleted inventory quickly with new items. Slow-selling items equate to higher holding costs compared to the faster-selling inventory. There is also the opportunity cost of low inventory turnover; an item that takes a long time to sell prevents the placement of newer items that may sell more readily.

Inventory turnover is an especially important piece of data for maximizing efficiency in the sale of perishable and other time-sensitive goods. Some examples could be milk, eggs, produce, fast fashion, automobiles, and periodicals. An overabundance of cashmere sweaters may lead to unsold inventory and lost profits, especially as seasons change and retailers restock with new, seasonal inventory. Such unsold stock is known as obsolete inventory or dead stock.

Some retailers may employ an open-to-buy system as they seek to manage their inventories and the replenishment of their inventories more efficiently. Open-to-buy systems, at their core, are software budgeting systems for purchasing merchandise. Such a system can be used to monitor merchandise and may be integrated into a retailer's financing and inventory control processes.

It can help small retailers better manage decisions on how much inventory to buy, how to evaluate how inventory is performing, and assist with future inventory procurement. Such software may be tailored to some degree but may not be useful for all types of merchandise. For example, it may work best with seasonal merchandise and fashion, but may not be a good fit for fast-selling consumer goods or basic items and staples.

When comparing or projecting inventory turnover one must compare similar products and businesses. For example, automobile turnover at a car dealer may turn over far slower than fast-moving consumer goods (FMCG) sold by a supermarket (snacks, sweets, soft drinks, etc.). Trying to manipulate inventory turnover with discounts or closeouts is another consideration, as it can significantly cut into return on investment (ROI) and profitability.

How to Use Inventory Turnover

Assume Company ABC has $1 million in sales and$250,000 in COGS. The average inventory is $25,000. The company has an inventory turnover of 40 or$1 million divided by $25,000 in average inventory. In other words, within a year, Company ABC tends to turn over its inventory 40 times. Taking it a step further, dividing 365 days by the inventory turnover shows how many days on average it takes to sell its inventory, and in the case of Company ABC, it’s 9.1. Alternatively, using the other method—COGS / Sales—the inventory turnover is 10, or$250,000 in COGS divided by $25,000 in inventory. Inventory is on hand for 36.5 days under this approach, or 365 / 10. As a real-life example, consider Wal-Mart Stores (NYSE: WMT), which has generated$512 billion in sales and $308 billion over the trailing 12 months as of Feb. 2019. Its inventory during the most recent quarter was$50.4 billion. Wal-Mart’s inventory turnover using the sales figure is 10.2. Using COGS, its inventory turnover is 6.1.

Inventory Turnover vs. Days Sales of Inventory

Inventory turnover shows how quickly a company can sale (turn over) its inventory. Meanwhile, days of inventory (DSI) looks at the average time a company can turn its inventory into sales. DSI is essentially the inverse of inventory turnover for a given period – calculated as (COGS / Inventory) * 365. Basically, DSI is the number of days it takes to turn inventory into sales, while inventory turnover determines how many times in a year inventory is sold or used.

Limitations of Using Inventory Turnover

When comparing or projecting inventory turnover one must compare similar products and businesses. For example, automobile turnover at a car dealer may turn over far slower than fast-moving consumer goods sold by a supermarket. Trying to manipulate inventory turnover with discounts or closeouts is another consideration, as it can significantly cut into return on investment and profitability.