SKU (Stock Keeping Unit)

Amazon & D2C glossary · Harpy Media

A SKU (Stock Keeping Unit) is the internal code a business assigns to each distinct sellable variant — distinguished by brand, style, colour, size, or pack configuration — and used to track that variant through inventory, orders, and accounts.

What is SKU?

A SKU (Stock Keeping Unit) is the internal code a business assigns to each distinct sellable variant — distinguished by brand, style, colour, size, or pack configuration — and used to track that variant through inventory, orders, and accounts.

It is your identifier, not the platform’s. The distinction matters because the two serve different purposes: one identifies your product internally across systems and suppliers, while the other is the marketplace’s own catalogue identifier. Businesses that confuse them, or let the platform generate internal codes, end up with inventory data they cannot reconcile.

Why naming conventions are load-bearing

A structured code carries information: what the product is, which variant, which supplier, which pack. That structure is what allows a warehouse to pick correctly, a spreadsheet to sort meaningfully, and a reconciliation to find the item it is looking for. Letting the system generate random strings throws all of that away — the code still identifies the item, but only to the system that made it.

Where multi-channel selling is involved the cost compounds. A SKU that is consistent across the marketplace, other sales channels, and the warehouse management system is the thread that connects the same physical item across every place it appears. Inconsistency turns every cross-channel question into manual investigation.

Designing a scheme that survives growth

Keep it readable and consistent: a fixed structure with defined segments, no spaces or ambiguous characters, and the same pattern for every product family. Include the attributes that actually vary — variant, pack size, supplier where relevant — and keep it stable, because changing codes after launch breaks the history attached to them.

The scheme will outlive the products it was designed for, so build it for the catalogue you expect rather than the one you have. Sellers who spend an hour defining a convention early save many hours of picking errors, mis-mapped feeds, and inventory discrepancies later — and mismapped inventory is one of the more expensive classes of operational error.

In practice

A brand defines a simple convention early — product code, variant, and pack size in a fixed order — and applies it across the marketplace listings, its own warehouse, and its channel integrations. Picking errors drop, feeds map cleanly, and when a discrepancy appears the item can be traced across every system it touches within minutes.

How Harpy Media helps

Catalogue and inventory structure is part of how we set brands up: naming conventions defined early, identifiers consistent across channels, and the reconciliation between systems made reliable rather than manual.

SKU FAQ

What is a SKU?

Stock Keeping Unit — the internal code identifying a specific sellable variant of a product, used to track it through inventory, orders, and accounting. It belongs to your business rather than to the platform.

How is a SKU different from an ASIN?

The ASIN is the marketplace’s catalogue identifier for a product. The SKU is your own internal code for the variant you sell. One product can have several SKUs — different packs, for example.

Why does the naming convention matter?

Because the code is what a warehouse picks against, a spreadsheet sorts by, and an integration maps to. A structured code carries information; a random one only identifies the item, and only to the system that generated it.