Fill Rate
Definition
The percentage of customer demand satisfied immediately from available stock, measured by units, lines, or complete orders. It captures how much demand you actually fulfilled, not just whether a stockout occurred.
In Practice
Fill rate comes in flavors that matter. Unit fill rate measures units shipped versus units ordered; line fill rate measures order lines fully satisfied; order fill rate is the strictest, counting only orders shipped complete. The same operation might post a 97 percent unit fill but an 88 percent order fill, and customers experience the order-level number.
Day to day, fill rate is the service metric planners defend. It ties directly to safety stock and replenishment quality, and it is often written into customer contracts with financial penalties, which makes measurement definitions worth getting agreed in writing.
Example: a grocery supplier receives an order for 10 lines totaling 1,000 units and ships everything except 60 units short on two lines. Unit fill is 94 percent, line fill is 80 percent, and order fill is 0 percent. The account team and the planner need to know which number the retailer's scorecard uses.
Related Calculators
Related Terms
The target probability of not stocking out during a replenishment cycle, or more broadly the standard of product availability promised to customers. It is the key input for sizing safety stock.
Stockout CostThe cost incurred when demand cannot be met from available inventory, including lost sales, expediting, penalties, and damaged customer relationships. It is the counterweight to holding cost in service level decisions.
BackorderA customer order, or portion of one, accepted for fulfillment despite the item being out of stock, to be shipped when inventory becomes available. Managing backorders means tracking, prioritizing, and clearing this unmet demand.
Safety StockExtra inventory held beyond expected demand to protect against variability in demand or supply. It acts as a buffer that keeps orders flowing when forecasts miss or deliveries run late.