Days Inventory Outstanding

Days Inventory Outstanding (DIO), also known as the inventory days or days in inventory, is a financial metric that measures the average number of days a company takes to sell its inventory during a specific period. It provides insight into the efficiency of a company's inventory management and indicates how well the company is converting its inventory into sales. A lower DIO generally implies that a company is selling its inventory more quickly, which is favorable for cash flow and reduces the risk of holding obsolete inventory. Conversely, a higher DIO suggests that the company takes longer to sell its inventory, which can tie up cash and increase carrying costs.

To calculate Days Inventory Outstanding, use the following formula:

DIO = (Average Inventory / Cost of Goods Sold) × Number of Days in Period


  • Average Inventory is the average value of the inventory during the period, usually calculated as the sum of the beginning and ending inventory values divided by two.
  • Cost of Goods Sold (COGS) represents the total cost of producing the goods that were sold during the period.
  • Number of Days in Period refers to the number of days in the accounting period, typically 365 days for a year or 90 days for a quarter.

For example, if a company's average inventory is $5 million, its cost of goods sold for the year is $20 million, and there are 365 days in the year, the DIO would be:

DIO = ($5,000,000 / $20,000,000) × 365 = 91.25 days

This means it takes the company an average of 91.25 days to sell its inventory.

It's important to note that the ideal DIO varies depending on the industry and the nature of the business. Companies in industries with fast inventory turnover, such as grocery stores or e-commerce, typically have lower DIOs, while those in industries with slower inventory turnover, such as heavy machinery or luxury items, may have higher DIOs. To assess a company's DIO performance, it's helpful to compare it with industry benchmarks and track its DIO trends over time.

See Also

  • Inventory Management- Both DIO and inventory management are used to evaluate inventory efficiency.
  • Working Capital - Working capital is a financial metric that includes inventory as one of its components, and DIO affects the liquidity and operational efficiency that working capital represents.
  • Days Sales Outstanding] - Like DIO, Days Sales Outstanding is a measure of how long it takes for a company to collect payment after a sale has been made. Both are components of the Cash Conversion Cycle.
  • Days Payable Outstanding - Days Payable Outstanding measures how long it takes for a company to pay its suppliers. Like DIO and DSO, DPO is also a component of the Cash Conversion Cycle.
  • Just-in-time (JIT)- Just-In-Time Inventory is a contrasting approach to managing inventory, aimed at minimizing inventory levels, which would effectively lower DIO.
  • Supply Chain Management (SCM) - Efficient supply chain management can significantly impact DIO by improving inventory turnover and reducing holding costs.
  • Financial Ratio - Financial ratios encompass a variety of metrics, including DIO, that are used for evaluating the financial health of a company.
  • Cost of Goods Sold (COGS) - DIO is often calculated using COGS, making it a closely related concept.
  • Gross Margin - Gross Margin can be influenced by how effectively a company manages its inventory, which is directly related to DIO.
  • Liquidity Ratio - These ratios, like the current ratio and quick ratio, often consider inventory as a component and can be related to a company’s DIO.
  • Capital Budgeting - Although more distantly related, capital budgeting decisions can affect inventory levels and thus DIO.
  • Financial Statement - DIO is often derived from data available in financial statements, making this an important area for anyone interested in DIO.