Reorder Quantity
Is reorder quantity the same as reorder point?
No. Reorder point is the inventory level that triggers action; reorder quantity is the size of the replenishment order. Both must be set accurately to maintain availability without overstocking.
What formulas are commonly used to calculate reorder quantity?
A common planning form is (average daily usage × lead time) + safety stock; some systems instead use EOQ, fixed quantity, or order-up-to logic. The best formula depends on demand stability, ordering costs, and holding costs.
When is EOQ used as a reorder quantity method?
EOQ is used when demand, ordering cost, and holding cost are sufficiently known to optimize order size; several ERP systems explicitly support EOQ as a reorder quantity method. It is most appropriate for stable, continuous demand items rather than intermittent or highly variable items.
Reorder quantity is the amount of inventory ordered when stock reaches a reorder trigger; it answers how much to order, while reorder point answers when to order. In ERP/WMS settings, it may be configured as a fixed quantity, an EOQ-based quantity, or a calculated amount adjusted for minimums, case packs, and price breaks.
On a shop floor or in warehouse replenishment, reorder quantity is the purchase or transfer lot size generated after a material hits its reorder point, so production can continue without line stoppage while avoiding excess inventory. In MRP/ERP practice, the quantity may be derived from average daily usage, lead time, and safety stock, or from system logic such as fixed reorder quantity, difference quantity, maximum-to-level, or EOQ rules. This matters for raw material tracking because the reorder quantity must align with actual consumption, supplier pack constraints, and storage capacity; otherwise, the system can recommend replenishment that is technically correct but operationally unusable on receiving, kitting, or staging docks. For manufacturing, the main operational function is to convert a stock trigger into a replenishment order that covers demand through the next receipt window and preserves material availability at point of use.
Under-ordering during variable demand or long lead times: If reorder quantity is set too low relative to actual consumption or lead-time risk, the line can run out before the next receipt, causing work stoppages, partial kits, or expedited buys.
Over-ordering due to ignoring case packs, MOQ, or storage limits: A formula-only quantity may not respect supplier minimum order quantities, pallet layers, or rack capacity, creating receiving congestion, excess carrying cost, and slow-moving stock.
Using stale demand history or wrong policy code: In ERP configurations, a bad quantity code, outdated usage history, or mis-set reorder parameters can generate misleading reorder quantities, especially when demand is intermittent or new-item history is insufficient.