Days of Supply

A key inventory metric that calculates how many days current stock levels will last based on average daily consumption or demand patterns. This measurement divides available inventory quantity by the average daily usage rate to project when stockouts may occur.

Days of supply serves as a critical planning tool for warehouse managers, enabling proactive replenishment decisions and preventing costly stockouts or overstock situations. It helps optimize inventory investments by maintaining appropriate safety stock levels while minimizing carrying costs. The metric also supports demand forecasting and supplier relationship management by providing visibility into reorder timing.

For example, if a warehouse holds 500 units of a product with an average daily consumption of 25 units, the days of supply equals 20 days (500 ÷ 25). This insight allows managers to initiate replenishment orders well before inventory depletion, accounting for supplier lead times and demand variability to maintain service levels.