Fixed Order Quantity

Fixed Order Quantity (FOQ) is a replenishment policy in which a constant quantity is ordered whenever inventory position falls to a predetermined reorder point; only the timing of the order changes, not the order size. It is also called the fixed-quantity model, fixed lot size model, or Q-system, with key parameters being order quantity (Q) and reorder point (ROP).

In a manufacturing or warehousing setting, FOQ is applied to predictable items such as raw materials, packaging, fasteners, and MRO consumables. The system continuously tracks inventory position, and when the balance reaches the reorder point, ERP or MRP logic triggers a purchase or transfer order for the same preset quantity every time. This quantity is often sized using EOQ to balance ordering and holding costs. On the shop floor, the approach standardizes replenishment, reduces decision variance, and keeps critical materials available without requiring a full periodic review. However, it depends on accurate stock records, disciplined cycle counting, and timely receipt posting. Warehouse teams must also plan receiving slots and putaway capacity because each order delivers the same fixed volume. FOQ works best when demand is stable and lead times are known; under those conditions, it enables smoother material flow, less expediting, and tighter inventory control.

• ⚠️Stockouts from a mis-set reorder point: When lead time or usage assumptions are inaccurate, the reorder point sits too low, the fixed order releases late, and production can stop waiting for material.
• ⚠️Excess inventory and dock congestion: An oversized fixed quantity forces the plant to receive too much at once, raising carrying costs, using up floor space, and locking cash in slow-moving stock.
• ⚠️Duplicate orders from receipt lag: When inbound receipts are posted late or missed, the system still sees low inventory, triggers another fixed order, and the true shortage is hidden in high-turnover operations.