SKU (stock keeping unit)
A stock keeping unit (SKU) is a unique internal code a retailer assigns to each distinct product variant — by size, color, or style — to track inventory. Unlike a manufacturer's UPC, SKUs are seller-defined and seller-controlled. Each variant gets its own SKU, so a shirt in five colors and three sizes needs fifteen SKUs for accurate stock control.
How it works
A SKU is an internal, alphanumeric code you create and assign to each sellable variant. There's no fixed formula — many merchants encode meaning into the structure, such as TS-BLU-M for a blue medium t-shirt, combining product family, attribute, and size segments.
The only hard rule is that every distinct variant gets exactly one unique, stable code. A shirt sold in 5 colors and 3 sizes is 5 × 3 = 15 SKUs, each tracked separately.
Why it matters
In Shopify, the SKU is the field that ties a variant to your purchase orders, inventory counts, and reports. Consistent, unique SKUs let you reconcile stock across locations, map supplier catalogs to your variants, and avoid the duplicate-or-missing-code chaos that breaks reorder automation. Get SKUs right first — almost everything downstream depends on them.
Track this automatically
Logistified calculates and monitors metrics like this across your whole Shopify catalog and turns them into reorder alerts and purchase orders.