Inventory Turnover
Inventory turnover is a financial efficiency ratio measuring how many times a company sells and replaces its inventory over a given accounting period, calculated by dividing the cost of goods sold (COGS) by average inventory; a higher ratio indicates faster inventory movement and more efficient working capital management, while a low ratio may signal excess inventory, slowing demand, or obsolescence risk.
Key takeaways
- Inventory Turnover = COGS / Average Inventory; Average Inventory = (Beginning Inventory + Ending Inventory) / 2.
- Days Sales in Inventory (DSI) = 365 / Inventory Turnover, converting the ratio to a time-based metric showing how many days it takes to sell existing inventory.
- Turnover ratios vary dramatically by industry: grocers may turn inventory 20-30x annually, while luxury goods or aerospace companies may turn inventory 2-4x annually.
- Declining inventory turnover is a warning signal of either weakening demand (inventory accumulating unsold), supply chain buildup in anticipation of shortages, or operational inefficiency.
- Inventory valuation method (FIFO, LIFO, or weighted average cost) affects both the reported inventory balance and COGS, creating comparability challenges across companies and geographies.
Explanation
Inventory turnover is a fundamental metric in operational and financial analysis because inventory management sits at the intersection of sales effectiveness, supply chain efficiency, and working capital optimization. For any business that manufactures, purchases, or distributes physical goods, inventory represents a significant deployment of capital—cash tied up in raw materials, work-in-progress, and finished goods awaiting sale. Turning that inventory faster means faster conversion of capital invested into revenue, lower storage and obsolescence costs, and reduced financing needs for working capital.
The ratio is computed as COGS divided by average inventory. Using COGS rather than revenue in the numerator is important: COGS and inventory are both recorded at cost, making the ratio a true measure of inventory flow relative to the investment in inventory. Using revenue (at selling prices) would overstate the numerator relative to the denominator (at cost), inflating the ratio artifically. Average inventory is used in the denominator rather than ending inventory to smooth the impact of seasonal fluctuations—particularly important for retailers with massive holiday season inventory buildups and drawdowns.
Industry context is essential for interpreting inventory turnover. Fast-moving consumer goods (FMCG) companies and food retailers operate with extremely high turnover ratios because goods are perishable and sold within days to weeks of receipt. A grocery chain with $10 billion of COGS and $350 million of average inventory turns inventory approximately 29x annually—roughly once every 13 days. In contrast, an aerospace manufacturer producing aircraft over 18-month assembly cycles will have inventory turnover well below 2x annually, with days sales in inventory exceeding 200 days. Neither is inherently good or bad; what matters is performance relative to industry peers and historical trends.
Changes in inventory turnover over time are early warning indicators of emerging business problems or management execution issues. A persistent decline in turnover for a consumer electronics company—from 8x to 5x over two years—may indicate that product cycles are elongating, demand for current product lines is disappointing, or the company has over-ordered in anticipation of demand that has not materialized. These are exactly the conditions that can precipitate inventory write-downs, margin pressure from promotional discounting, and negative free cash flow surprises. Short-sellers pay close attention to inventory-to-sales ratios and channel checks (surveys of retailers and distributors) to identify such situations before they appear in reported results.
The accounting method used to value inventory creates important comparability issues. Under FIFO (First In, First Out), the oldest inventory costs are assigned to COGS and the most recent costs remain on the balance sheet—during inflationary periods, FIFO produces higher reported profits and higher ending inventory values. Under LIFO (Last In, First Out, permitted only under U.S. GAAP but not IFRS), the newest costs flow to COGS and older, lower costs remain on the balance sheet—LIFO produces lower profits during inflation but may significantly understate current replacement cost of inventory. Comparing inventory turnover across FIFO and LIFO companies requires careful adjustment for LIFO reserves disclosed in footnotes.
Formula
Inventory Turnover = COGS / Average Inventory; Days Sales in Inventory (DSI) = 365 / Inventory Turnover
Example
Nike reported COGS of approximately $23.7 billion for fiscal year 2023, with beginning inventory of $9.7 billion and ending inventory of $8.5 billion, giving average inventory of $9.1 billion. Nike's inventory turnover ratio is $23.7B / $9.1B = 2.6x, equivalent to 140 days of inventory on hand (365 / 2.6). This compares to approximately 4.0x (91 days) in fiscal 2021 when supply chains were constrained and inventory was scarce. The deterioration in turnover from 2021 to 2023 reflected Nike's over-ordering to compensate for supply chain disruptions in 2020-2021, followed by weaker-than-expected demand in 2022-2023—a pattern that forced significant promotional discounting to move excess inventory and pressured gross margins by 200-300 basis points.
Related terms
Balance Sheet Basis Cost Of Debt Current Ratio Evebitda Multiple Free Cash Flow Gaap Vs Non Gaap Inflation Margin Working Capital