What inventory turnover tells you
Inventory turnover shows how many times you sell through your average stock during a period. It answers a practical question, not an accounting one: are you holding too much stock for how fast it moves? When turnover is low, cash stays trapped on shelves for too long. When turnover is strong, stock moves quickly, cash returns faster, and the business usually needs less working capital to support the same level of sales.
The companion metric is days in inventory. That converts turnover into plain language by showing how long stock tends to sit before it is sold. Founders, store operators, wholesalers, and ecommerce teams usually understand that number faster because it describes the real operating consequence directly.
The core formula
Average inventory = (Opening inventory + Closing inventory) ÷ 2
Inventory turnover = COGS ÷ Average inventory
Days in inventory = Period days ÷ Inventory turnover
Reorder point by value = Daily COGS usage × (Lead time + Safety days)
Use cost of goods sold, not revenue, in the turnover formula. Revenue can make turnover look better than it really is because turnover is based on the cost value of stock, not the selling price.
How to read the result
| Signal | What it means | Likely action | Risk level |
|---|
| Very low turnover | Stock is moving slowly | Reduce purchase volume, bundle, discount, or clear dead stock | High |
| Balanced turnover | Inventory is moving at a healthy pace | Keep replenishment stable and monitor trends | Good |
| Very high turnover | Stock moves fast, but stockout risk rises | Review reorder timing and safety stock | Caution |
| Days in inventory too high | Cash is tied up too long | Trim SKUs, improve forecasting, order smaller batches | High |
| Reorder point too low | Lead-time stockout risk | Increase buffer or place orders sooner | Critical |
Frequently Asked Questions
Should I use revenue or COGS for inventory turnover?+
Use COGS. Inventory turnover is based on the cost value of stock, not the selling price. If you use revenue, the turnover number will usually look stronger than reality because markup gets mixed into the result. That can hide slow-moving stock and make the business think inventory is healthier than it is. Revenue is still useful for gross margin return on inventory, but not for the core turnover formula.
Is a high inventory turnover always good?+
Not always. High turnover is often good because it means cash is not trapped in stock for long. But if it becomes too high, the business may be cutting inventory too close and increasing the chance of stockouts, rush shipping, lost sales, or weak customer experience. The right turnover depends on lead time, seasonality, stock reliability, and how costly it is to run out of stock. This is why turnover should always be read together with reorder timing and safety stock.
What is days in inventory and why does it matter?+
Days in inventory translates turnover into a more intuitive number by showing roughly how long stock sits before being sold. Many business owners understand this faster than a turnover ratio. If stock sits for 120 days, that means cash is parked for about four months before returning. If it sits for 25 days, cash comes back much faster. Lower days in inventory generally improves working capital efficiency, though the ideal level still depends on demand stability and lead time risk.
What is dead stock and how does it affect turnover?+
Dead stock is inventory that is not moving or is moving so slowly that it is unlikely to sell at full value within a reasonable time. It hurts turnover because it inflates average inventory without helping COGS move higher. That pushes the turnover ratio down and days in inventory up. Dead stock also damages cash flow because the business already paid for the goods but does not recover that cash quickly. Removing or discounting dead stock often improves both turnover and working capital clarity.
How do lead time and safety stock affect reorder point?+
Lead time tells you how long you will wait after placing a new order. Safety stock adds extra coverage in case sales rise unexpectedly or suppliers deliver late. The reorder point combines both. If daily usage is high and lead time is long, the reorder point needs to be higher. If safety stock is too small, the business may run out before new inventory arrives. If safety stock is too large, too much cash stays tied up in inventory. The right balance protects service without wasting cash.
What is margin return on inventory and why should I care?+
Margin return on inventory, often called GMROI, shows how much gross profit the business generates for each currency unit invested in average inventory. It is useful because it combines margin and stock efficiency into one view. Two businesses can have the same turnover, but the one with stronger gross margin usually creates more value from each inventory dollar or euro. It is especially useful for retailers and ecommerce brands comparing product categories, private label lines, or supplier mixes.