Days Sales of Inventory (DSI), sometimes called Days Inventory Outstanding (DIO), measures how many days it takes, on average, to sell through the inventory you're holding. It's a cash-flow-oriented way of looking at the same underlying efficiency that inventory turnover measures.
DSI Calculator
Days Sales of Inventory
60.8 days
Equivalent to 6.0x inventory turnover per period
The DSI formula
DSI = (Average Inventory ÷ Cost of Goods Sold) × Number of Days in the Period. Average inventory is typically (beginning inventory value + ending inventory value) ÷ 2 for the period; COGS is the direct cost of inventory sold during that same period.
Example: a business carries $40,000 in average inventory and has $240,000 in annual COGS. DSI = (40,000 ÷ 240,000) × 365 ≈ 61 days — it takes roughly two months, on average, to sell through the stock on hand.
DSI and inventory turnover are the inverse of each other (turnover = 365 ÷ DSI, and vice versa). Neither is universally "better" to track — DSI is more intuitive for cash-flow conversations ("how many days of cash is tied up"), turnover is more common for comparing efficiency across periods or SKUs.
See also: the DSI glossary entry, the inventory turnover calculator, the inventory turnover guide.
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