What a GTIN is
A Global Trade Item Number (GTIN) is the globally unique identification key that GS1 defines for a product or trade item. It is the number encoded in most retail barcodes and, increasingly, in the GS1 Digital Link QR code that connects a physical item to online information such as a Digital Product Passport.
A GTIN identifies a product type or configuration, for example a specific style in a specific colour and size, so that any company in the world can refer to the same item without ambiguity.
GTIN-8, GTIN-12, GTIN-13 and GTIN-14
- GTIN-13 is the common retail format, historically the EAN-13 barcode.
- GTIN-12 is the North American UPC format.
- GTIN-8 is used for very small packaging.
- GTIN-14 identifies a packaging level such as a case or carton, often built from the base GTIN.
Shorter GTINs can be represented in a 14-digit field by padding with leading zeros, which is why many systems store every GTIN as 14 digits.
GTIN versus SKU versus serial number
A SKU is an internal stock keeping unit that each company defines for itself, so two companies can use the same SKU for different products. A GTIN is global and unambiguous. A serial number goes further and identifies one individual unit rather than the product type. Cycle keeps all three: the GTIN for global identity, the SKU for internal operations and an optional serial for unit-level traceability.
The check digit and validation
The last digit of a GTIN is a check digit calculated from the others with a fixed modulo-10 formula. A single mistyped digit usually breaks the check, which is why a GTIN should always be validated before it is printed on a label or encoded in a QR code. You can validate a GTIN and its GS1 Digital Link form for free with Cycle's machine tools for AI agents.
GTIN and the Digital Product Passport
Where a GTIN exists, it is the natural anchor for a product passport. The EU framework requires a passport to connect through a data carrier to a persistent unique identifier, and a GS1 Digital Link lets one QR code carry the GTIN plus, when needed, a batch or serial. Products without a GTIN can still be identified with an alternative persistent identifier and upgraded later.