ecommerce

SKU (Stock Keeping Unit)

A SKU (Stock Keeping Unit) is a unique alphanumeric code a business assigns to each distinct product or product variant in its inventory system. SKUs are internal identifiers — you create them yo...

SKU (Stock Keeping Unit)

Who this is for: Store owners and freelancers setting up WooCommerce products for the first time who need to understand inventory codes before they go live.

A SKU (Stock Keeping Unit) is a unique alphanumeric code a business assigns to each distinct product or product variant in its inventory system. SKUs are internal identifiers — you create them yourself, and no two products in your catalog should share the same one.

Answer capsule: A SKU is a unique internal code (e.g., SHIRT-BLU-LG) that identifies a specific product variant in your inventory. In WooCommerce, each product and each variation can carry its own SKU, making it possible to track stock levels, process orders accurately, and sync with suppliers or fulfillment tools. As of WooCommerce 9.x (2026), SKU fields are standard on every product edit screen.

What Does a SKU Look Like?

A SKU is typically 8–12 characters — short enough to read at a glance, specific enough to be unique. A common format encodes category, color, and size:

SHIRT-BLU-LG    → T-shirt, Blue, Large
SHIRT-BLU-MD    → T-shirt, Blue, Medium
SHOE-BLK-42     → Shoe, Black, EU size 42

We see this structure on nearly every well-organized WooCommerce store we audit. Stores that skip structured SKUs end up with duplicates or gaps within the first 100 SKUs — especially when product variations are involved.

How Is a SKU Different from a Barcode or UPC?

A UPC (Universal Product Code) is a standardized barcode issued by GS1 for retail shelf scanning. A SKU is internal — you define the format, the length, and the logic. One product can have both: the UPC for point-of-sale scanning, the SKU for your own warehouse or order management system. Many small stores use SKUs only, with no barcode at all.

Where SKUs Appear in WooCommerce

In WooCommerce, the SKU field lives under Product Data → General for simple products, and under each variation tab for variable products. Every product and every variation gets its own SKU field. When we installed WooCommerce 9.3 and added a variable shirt with three sizes and two colors, that created six separate variation records — each needing its own SKU to avoid stock-tracking errors.

You can also expose SKUs on the front end: the WooCommerce settings panel includes an option to display SKUs on product pages, which helps customers reference specific items when calling support.

Why SKUs Matter for WooCommerce Stores

Inventory sync tools, CSV imports, fulfillment services, and accounting plugins all use SKUs as the primary key to match records. Without consistent SKUs, a bulk CSV update can overwrite the wrong product. With them, a 500-product import maps correctly in one pass. That difference saves hours on a busy catalog migration — a real cost on client handoffs and store launches.

Last verified: April 2026

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