What Is Days Inventory Outstanding (DIO)?
Days inventory outstanding measures the average number of days a company holds its inventory before it is sold. It converts the inventory balance into a number of days, answering a simple question: how long does stock sit before it turns into a sale? A lower DIO means inventory moves quickly and less cash is tied up on the shelf; a higher DIO means goods linger, which ties up cash and raises the risk of obsolescence. It is a core measure of inventory efficiency and the inventory side of the cash conversion cycle.
How to Calculate Days Inventory Outstanding
DIO = (Average Inventory / Cost of Goods Sold) x Number of Days in the Period
Worked example, for a year:
- Average inventory: $1,000,000
- Annual cost of goods sold: $6,000,000
- Days in period: 365
- DIO: (1,000,000 / 6,000,000) x 365 = about 61 days
On average, inventory sits about 61 days before it is sold.
DIO in Power BI (DAX)
Average inventory is often the average of the beginning and ending balance. Replace the measures with the ones in your model:
DIO = DIVIDE ( [Average Inventory], [Total COGS] ) * [Days In Period]DIO and Inventory Turnover
Days inventory outstanding and inventory turnover are two views of the same efficiency. Turnover counts how many times inventory cycles in a period; DIO converts that into the average days stock is held, and the two are linked by a simple relationship: DIO is roughly 365 divided by the annual turnover. A turnover of 6 corresponds to a DIO of about 61 days.
What Is a Good DIO?
The right level depends heavily on the industry and the goods. A grocer holding perishables runs a very low DIO; a dealer of heavy equipment runs a much higher one. DIO is most useful compared within an industry and tracked over time. The aim is balance: too high ties up cash and risks spoilage or obsolescence, while too low can mean stockouts and lost sales.
DIO and the Cash Conversion Cycle
DIO is one of the three components of the cash conversion cycle, alongside days sales outstanding and days payable outstanding. It captures how long cash is locked in inventory. Reducing DIO, by holding less stock or selling it faster, shortens the overall cash cycle and frees up working capital.
Reporting DIO From Your ERP Data
DIO depends on inventory and cost of goods sold drawn consistently from the ERP, which is harder across warehouses and entities. A governed data foundation brings inventory and cost data onto one model so DIO is consistent and traceable. QuickLaunch ships pre-built models for JD Edwards, Vista, NetSuite, and OneStream that surface inventory and cost data for operational reporting.
Frequently Asked Questions
How is days inventory outstanding calculated?
Divide average inventory by the cost of goods sold, then multiply by the number of days in the period. A company with $1M average inventory and $6M annual COGS has a DIO of about 61 days.
What is the difference between DIO and inventory turnover?
They are two views of the same efficiency. Inventory turnover counts how many times stock cycles in a period; DIO converts that into the average days inventory is held, roughly 365 divided by turnover.
What is a good DIO?
It depends on the industry and the goods. It is best compared within an industry and tracked over time, with the aim of balance: too high ties up cash and risks obsolescence, too low risks stockouts.
