SKU
A SKU, or stock-keeping unit, is an internal identifier used to distinguish and track a specific product or product variant.
SKU systems are created by the business rather than being universal product identifiers.
What It Means in Practice
A retailer might assign:
TSHIRT-BLU-M
to:
Blue T-shirt, Medium
and:
TSHIRT-BLU-L
to:
Blue T-shirt, Large
Each purchasable stock item receives a unique identifier.
WooCommerce describes a SKU as a unique identifier used to search for and track a product or variation. WooCommerce's product inventory documentation
SKU vs. Barcode
A SKU is an internal business identifier.
A barcode may encode a standardized identifier such as a UPC, EAN, or GTIN.
A business can create its own SKU even when a manufacturer has already assigned the product a barcode.
The same physical product can therefore have:
- Manufacturer identifier
- Barcode / GTIN
- Retailer's SKU
These should not be assumed to be interchangeable.
Why It Matters
SKUs provide a dependable reference between systems.
They can connect:
- Product Catalogue
- Inventory
- Point of Sale
- Orders
- Fulfilment
- Product Feeds
- Accounting systems
- Warehouse systems
Stable identifiers are especially important when several products have similar names.
Common Problems
Common SKU problems include:
- Duplicate SKUs
- Changing identifiers without a reason
- Using product names as identifiers
- One SKU representing several physically different variants
- Different systems creating their own unrelated identifiers
- SKUs containing business logic that becomes outdated
How to Improve
Keep SKU rules predictable.
Each independently tracked stock item should generally have a stable unique SKU.
Document the naming convention and avoid changing identifiers simply because the product name or marketing copy changes.