SKU (stock keeping unit)
Also known as: Stock keeping unit
In short
An internal code a business assigns to a sellable product or variant to organize inventory, fulfillment and sales reporting.
Identify inventory inside your business
A stock keeping unit gives a business a consistent reference for an item it stocks or sells. The code may be readable, such as a combination of model and size, or an opaque identifier. Its format is a business decision.
Assigning a SKU does not create a globally recognized product identifier. A GTIN follows a separate identification system. A channel’s item ID is another field, although a merchant may choose to populate it with an existing SKU when the channel’s rules allow that.
For reliable variant tracking, use a distinct SKU for each sellable variation. Reusing a code across unrelated items makes joins between inventory, orders and reporting ambiguous.
Illustrative example
Imagine a store using MUG-BLU-350 for a blue 350 ml mug and MUG-WHT-350 for the white version. A warehouse can pick the requested color, and sales reports can separate the variants.
The manufacturer might supply a GTIN for each mug. Those GTINs belong in their own fields rather than replacing the internal codes without a migration plan.
Keep the mapping stable
Before changing SKU formats, check integrations, open orders and historical reports. Treat identifiers as data, including leading zeros. A spreadsheet that converts a code into a number can silently break a match even when the displayed value looks familiar.