SKU (Stock Keeping Unit)
A unique internal identifier brands and retailers assign to each product variant for inventory, pricing, and operations.
A SKU (Stock Keeping Unit) is a unique alphanumeric code a business assigns to each distinct product variant to track inventory, pricing, and fulfillment. Unlike a GTIN or UPC — which are globally standardized — a SKU is internal: you design it, you own it, and it only has to be unique within your own operation.
What does a SKU look like?
SKUs are usually structured codes that encode meaningful attributes. For example, a t-shirt SKU TSHIRT-RED-L breaks down into product (t-shirt), color (red), and size (L). Good SKU schemes are short, human-readable, consistent, and never reused.
SKU vs GTIN vs UPC vs MPN
These identifiers are easy to confuse:
- SKU — your internal code for a variant, unique to your business.
- GTIN — a globally unique product number administered by GS1 (an umbrella that includes UPC and EAN).
- UPC — the 12-digit barcode standard used in North American retail.
- MPN (Manufacturer Part Number) — the code the manufacturer assigns to a part or product, shared across all resellers.
Why SKUs matter in a PIM
In a PIM, the SKU is the key that ties a canonical product record to inventory and orders across every channel. Apimio uses SKUs to map products between Shopify stores, dedupe variants, and keep multi-store catalogs in sync — so one SKU resolves to one consistent listing everywhere it sells.