Kanban Size
Is kanban size the same as the number of kanban cards?
No. Kanban size is the units per container or card, while the number of cards is the count of circulating authorization signals; Oracle and kanban sizing references distinguish between container quantity and card count.
What variables drive kanban size most strongly?
Average demand, replenishment lead time, safety stock or variability buffer, and container/lot constraints are the dominant drivers in the formulas documented by Oracle and common kanban sizing guidance.
Why do some systems use a fixed-container formula while others size the number of cards?
Fixed-container implementations calculate the container quantity directly, while other methods compute card count from demand divided by container size; both approaches are equivalent if the same demand, lead time, and buffer assumptions are used.
Kanban size is the quantity of units in one kanban container or card loop, authorizing that many units to be consumed before replenishment is triggered. It is calculated from average daily demand multiplied by replenishment lead time plus safety stock, and should align to lot or pack sizes. In manufacturing planning, this value directly controls material visibility and replenishment frequency.
On the shop floor, kanban size fixes the authorized container quantity circulating between a consuming operation and its upstream replenisher. That single number governs how much material is scanned, picked, issued, and counted, so it normally matches a case, tote, drum, or pallet rather than an arbitrary piece count. Planners translate demand, lead time, and variability into a standard pack quantity, then round up or adjust to lot-size and handling constraints. Too-small containers force impossible supplier runs and create stockouts before the next bin arrives; too-large containers inflate WIP, consume floor space, and hide process instability. In a point-of-use supermarket, the same size determines how many units are visible at once, driving scan frequency, replenishment labor, and the time between an empty signal and the next full container. Aligning size with the upstream process's feasible lot size prevents partial shipments, broken standard work, and repeated receiving exceptions.
Stockout from undersized kanban: When daily demand or lead time is understated, the authorized container empties before replenishment returns, forcing line stoppage, expedited transfers, and missed production commitments.
Excess inventory from oversized kanban: Padding the size too aggressively carries too much material in the loop, increasing floor space use, aging risk, and hidden overproduction while masking true process instability.
Replenishment mismatch to lot size: When kanban size is not a multiple of the supplier's or upstream process's feasible lot size, the replenishment order cannot be filled cleanly, causing partial shipments, broken standard work, and repeated exceptions at receiving.