Size Curve

A size curve is the percentage distribution of a buy across sizes for a style — what share of units go to each size, whether an S–XL apparel run or a full footwear size run. Buying and replenishing to the right curve is what keeps core sizes in stock through the season.

A curve should be built from sell-through history, not receipts — receipts show what you bought, while sell-through shows what customers actually took, including the sizes that stocked out early.

Aggregate sell-through can look healthy while the core sizes have been out of stock for weeks — the size curve is where that truth lives. A size-level view turns “the style sold through” into “we lost the middle of the run early.”

A wrong curve creates broken size runs and markdowns: core sizes sell out while fringe sizes linger and end up cleared. Pack configurations and reorders should both track the curve, not an even split across sizes.