Size Run

A size run is the full set of sizes a model-color is bought and stocked in as one unit — in footwear, the sizes, the half sizes between them, and where the model offers them, the widths. It is what a footwear buyer commits to: a model-color is bought not as a quantity of pairs but as a number of runs, each a complete ladder from the smallest size the channel stocks to the largest. The run is also the sellable position. A customer who cannot find their size does not buy a nearby one, so a model-color with the middle of its run missing is unsellable at full price long before the pair count says anything is wrong.

The term is often confused with the size curve. The size curve is the distribution — the share of units planned at each size; the size run is the object that distribution is applied to. A curve says the middle sizes take the largest share of a buy; a run is the physical ladder of pairs in one location that either is or is not complete. Apparel plans a curve across a handful of sizes and can absorb a missing one. Footwear plans across a ladder that half sizes double and widths multiply again, and the sellable position depends on the ladder staying whole.

Breakage and minimum depth per run

A run breaks when the sizes that sell fastest are gone and the ends remain. Demand concentrates in the middle of the curve, so the middle depletes first and the run is broken while most of the pairs are still in stock. The consequence for the buy is a minimum depth per run: the smallest number of pairs at each size that keeps the run complete through the selling window at the expected rate. Below it, the model-color is a broken run in waiting, and the pairs at the ends of the ladder are the ones still there at clearance. Depth in footwear is set by run integrity, not by total pairs, which is why thin depth across many colorways produces more residual than the same pairs concentrated in fewer complete runs. The pre-pack vs singles entry covers how the run is physically ordered; the MOQ entry covers the factory minimum the run has to clear.

Prebook implications

In wholesale footwear a dealer prebooks runs, not pairs, and the runs the dealer chooses — which half sizes, which widths — fix the sizes the brand holds as at-once fill-in stock. A brand that prebooks a narrow run and holds a full one for fill-in is funding the ends of the ladder itself; one that holds a narrow fill-in run against a full prebook run cannot repair a dealer's broken run when the reorder arrives. The run decision at prebook is a channel decision as well as a buy decision. Once a run is broken, the exit lever is consolidation — pulling the fragments of the same model-color from several doors into one sellable run — then a pair-level exit for what remains, because a markdown on the sizes left does not restore the ones that are gone. The buy mechanics are in assortment planning for footwear brands; the exit mechanics are in markdown and exit strategy by vertical.

RetailNorthstar plans footwear at the size-run level — pairs by size and width, with the size curve and the prebook position held in one place — so a broken run is visible in the plan rather than reconstructed from the pair count. See how RetailNorthstar plans for footwear brands →