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PIM Glossary

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.

Frequently asked questions

What is the difference between a SKU and a UPC?+

A SKU is your internal code, unique only to your business and designed by you. A UPC is a globally standardized 12-digit barcode administered through GS1 and shared across all retailers.

What is an MPN?+

MPN (Manufacturer Part Number) is the code the manufacturer assigns to a product or part. Unlike a SKU, the same MPN is shared by every reseller of that item, which helps marketplaces match listings.

How do I structure a good SKU?+

Keep SKUs short, human-readable, and consistent — encode attributes like product type, color, and size (e.g., TSHIRT-RED-L), never reuse retired codes, and keep them unique across your catalog.