What are UPC, EAN, ASIN, SKU, FNSKU, and GCID? About Amazon Product Codes

What’s the most essential thing to know about Amazon? You absolutely must distinguish between Amazon’s common codes, or else you’ll end up in a lot of confusion. The prevalent Amazon codes nowadays include ASIN, UPC, EAN, SKU, FNSKU, and GCID. Can you differentiate them now?


When uploading products to Amazon, most categories require sellers to use specific Global Trade Item Numbers (GTINs), which can be UPC, EAN, JAN, or ISBN, among others. The most commonly used by sellers are UPC and EAN codes.

UPC: The full name is “Universal Product Code.” It’s a barcode designated by the “Uniform Code Council” jointly organized by the United States and Canada, based on the Delta-Distance proposed by IBM. The UPC is a standardized identifier for products in the US and Canada. It’s a fixed-length, continuous barcode, consisting only of digits 0 to 9. The structure of the standard UPC12 code includes: System Code (1 digit) + Manufacturer Code (5 digits) + Product Code (5 digits) + Check Digit (1 digit).


EAN: The full name is “European Article Number.” EAN codes are identifiers for goods established by the International Article Numbering Association of the European Community, drawing from the experience of UPC. So far, dozens of member countries of this association have adopted the EAN barcode. Since the EAN code is based on the UPC code and has undergone further development and innovation, EAN barcode readers can read UPC barcodes, but UPC barcode readers cannot read EAN codes. The structure of the standard EAN13 code includes: Country Code (2/3 digits) + Manufacturer Code (5/4 digits) + Product Code (5 digits) + Check Digit (1 digit).


Differences between EAN and UPC:

  1. Different usage areas. EAN barcodes are used in over 90 countries and regions worldwide, while UPC barcodes are mainly used in the United States and Canada.
  2. Different issuing bodies. EAN barcodes are issued by the International Article Numbering Association, while UPC barcodes are issued by the Uniform Code Council in the United States.
  3. Different standard codes. EAN standard codes consist of 13 digits, whereas UPC standard codes consist of 12 digits.


ASIN: The full name is “AMAZON STANDARD IDENTIFICATION NUMBER,” Amazon’s product code.

The ASIN is a unique alphanumeric code randomly generated by Amazon for each product. Each ASIN corresponds to a unique product, meaning one ASIN corresponds to one UPC.

a. ASIN serves as a product’s ID on Amazon and is unique.
b. Format example: B07B9FZXJC
c. ASINs are searchable both on the platform’s frontend and in the seller’s backend.



SKU: The full name is “Stock Keeping Unit,” a product management code named by the seller.

The SKU is a unit for managing products in Amazon seller warehouses, which can be in units, boxes, pallets, etc. SKUs can consist of numbers or letters. SKU is not mandatory; if the seller doesn’t provide one, Amazon generates it automatically. Each product corresponds to one SKU, and SKUs in the store cannot be duplicated.

For single-variant products, SKU refers to one product, and each product has its own SKU for easy identification by the seller.

For multi-variant products, each variant (color, size, etc.) has its own SKU. For example, if a piece of clothing comes in four sizes (S, M, L, XL), there will be four corresponding SKUs. Using the same SKU for different variants can lead to confusion and shipping errors.

Note: ASIN is the only unchanging product ID on Amazon. One ASIN can correspond to multiple SKUs (sellers).


FNSKU: Amazon logistics code

FNSKU is different from SKU. It’s a product label code for FBA products only. Each FBA product SKU corresponds to one FNSKU.

a. Amazon assigns this code to sellers after the products are shipped to Amazon warehouses.
b. Format example: XOOOGRUH38



GCID: The full name is “Global Catalog Identifier,” a product registration GCID code.

GCID is a brand identifier generated internally by Amazon. After a seller’s brand is successfully registered on Amazon, Amazon automatically assigns a unique Global Catalog Identifier, which is a 16-character code consisting of letters and numbers. This GCID is equivalent to the UPC/EAN code in each listing, except that the UPC/EAN code for registered products can be omitted.

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  • Jack Hogan

    Jack Hogan, founder of NexaToys.com since 2014, is a seasoned professional in the toy industry, having successfully assisted over 10,000 clients in procuring the perfect toys.

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