Days Sales in Inventory (DSI)

Calculate Days Sales in Inventory

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What is Days Sales in Inventory (DSI)?

Days Sales in Inventory (DSI), sometimes known as inventory days or days in inventory, is a measurement of the average number of days or time required for a business to convert its inventory into sales. In addition, goods that are considered a “work in progress” (WIP) are included in the inventory for calculation purposes.

The DSI value is calculated by dividing the inventory balance (including work-in-progress) by the amount of cost of goods sold. The number is then multiplied by the number of days in a year, quarter, or month.

Days Sales in Inventory (DSI) - Formula

The DSI figure represents the average number of days that a company’s inventory assets are realized into sales within the year. Days sales in inventory is also one of the measures used to determine the cash conversion cycle, which is the company’s average days to convert resources into cash flows.

Formula for Days Sales Inventory (DSI)

To determine how many days it would take to turn a company’s inventory into sales, the following formula is used:

DSI  =  (Inventory / Cost of Sales) x (No. of Days in the Period)


For the year-end 2015 financial statements, Target Corp. reported an ending inventory of $1M and a cost of sales of $100M. Given the figures, the DSI for the year is 3.65 days, meaning it takes approximately 4 days for the company to sell its stock of inventory.

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Indications of Low and High DSI

Generally, a small average of days sales, or low days sales in inventory, indicates that a business is efficient, both in terms of sales performance and inventory management. Hence, it is more favorable than reporting a high DSI. A low DSI reflects fast sales of inventory stocks and thus would minimize handling costs, as well as increase cash flow.

On the other hand, a high DSI value generally indicates either a slow sales performance or an excess of purchased inventory (the company is buying too much inventory), which may eventually become obsolete. However, it may also mean that a company with a high DSI is keeping high inventory levels to meet high customer demand.

It is also important to note that the average days sales in inventory differs from one industry to another. To obtain an accurate DSI value comparison between companies, it must be done between two companies within the same industry or that conduct the same type of business. For example, a retail store like Wal-mart can be compared to Costco in terms of inventory and sales performance.

Importance of Days Sales Inventory to Businesses and Investors

For a company that sells more goods than services, days sales in inventory is an important indicator for creditors and investors, because it shows the liquidity of a business. The interested parties would want to know if a business’s sales performance is outstanding; therefore, through this measurement, they can easily identify such.

The more liquid the business is, the higher the cash flows and returns will be. Management is also interested in the company’s days sales in inventory to determine how fast inventory moves, which is important when taking storage and maintenance expenses of holding inventory into account.

The carrying cost of inventory, which includes rent, insurance, storage costs, and other expenses related to holding inventory, may directly impact profit margin if not managed properly. In addition, the longer the inventory is kept, the longer its cash equivalent isn’t able to be used for other operations and, thus, opportunity cost is lost.

Additional Resources

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