An item number is used to differentiate, categorize and uniquely identify retail items. It is assigned only once for a specific article or a specific variant of the corresponding article. This distinctiveness and uniqueness refers to the underlying system in each case. This can be the company’s own product range, its own warehouse or a globally valid standard.

Function and representation of item numbers

The numbering of articles is based on a numerical ordering system, which serves to identify or classify articles. Such systems are also called article encoding systems, and they can be created both individually and on an inter-company basis. In the former, companies have developed and established their own item numbers, while in the latter, international standards are used. There are different ways of compiling and representing an item number or the item code. The best known way of presentation is the barcode. In the EAN system or the GTIN system, the item number usually consists of four segments with a total of 13 digits, which have different levels of meaning and are arranged as follows:

  • Digits 1-3 distinguish the country
  • Positions 4-7 distinguish the company
  • Positions 8-12 distinguish the article
  • Position 13 serves as a check digit only

Each article is subject to this numbering. In addition, there are the corresponding different thin and thick bars that are read by scanners.

Barcode density overview
Barcode density overview

Overview of the structure and function of common item numbering systems

The most common international item numbers include EAN, GTIN, UPC and ISBN. An item number that is known outside the company but is only used within the company is, for example, Amazon’s ASIN (Amazon Standard Identification Number). The ASINs are relevant for the management of the product catalog at Amazon. The ASIN makes it possible to present the most suitable search result possible to the buyer search, making it easier for buyers to find products. In addition, ASINs help protect products from counterfeiting.

The International Standard Book Number (ISBN) is an item number that uniquely identifies books as well as other independent publications that have an editorial component. This can also include software or multimedia products. Originally 10-digit, it now has 13 digits, which is due to the fact that, on the one hand, the number range has been enormously increased and, on the other hand, compatibility with the EAN system has thus been achieved. This means that a 13-digit ISBN is identical to the corresponding EAN.

The EAN code (European Article Number) is the most widely used item number and was renamed GTIN in 2005. Both are accompanied by a corresponding representation as a barcode.

The GS1 standard and its advantages

When it was introduced in 1976, the goal was to ensure that the EAN would be a unique identification of inventories throughout Europe. After only a few years, EAN coding was also used in Asia, Africa, Australia and South America. In 2002, the EAN was merged with its North American equivalent UPC (Universal Product Code) to form today’s GS1 (Global Standards 1). Consequently, a new term was established for the compatible EAN and UPC identification systems: GTIN (Global Trade Item Number).

By means of the GTIN, the entire value chain is permeated by a single item number system. Thus, the GS1 standard is already firmly anchored in the production process, in that each individual item is assigned a unique item number, the GTIN, from procurement through manufacturing to the final product. Further information on processes such as storage, transport, trade, delivery and return is generally all stored on the code variant GS1 standard 128. Thus, each item receives a distinctive label that identifies it within a specific packaging hierarchy. In addition to the batch number and expiration date, for example, the article description, transport unit, identification and classification number, lot number and net weight can also be stored as additional data.

Advantages of the GS1 standard:

  • Quick acquisition at goods receipt or in the middle of the flow of goods
  • Flexible and fast creation of data carriers and labels
  • A cost-effective data storage medium
  • Combinable with plain text together on one data carrier
  • 16,000 or more scans per second, at a conveyor speed of 2.3 meters per second
  • Proven error-free barcode capture
  • Fewer manual processes, more automation
  • Real-time data reconciliation at a scanning station
Omerzu, Example of a Gs1-128 code, CC0 1.0

Application areas of item numbers and general advantages

Beyond the prevalence of item numbers along a value chain and in-house use, various benefits of item numbers can be derived in general, especially in retail, both brick-and-mortar and online. Item numbers ensure and enable:

  • The flawless, unambiguous article definition
  • The avoidance of product mix-ups
  • The automation of inventory management
  • The optimization of the movement of goods
  • The global standardization

Particularly in e-commerce, i.e. online trading, the item number is a prerequisite for being listed and selling on platforms and marketplaces such as Amazon. In distribution centers or systems, different item numbers can also designate the same item at different locations (storage locations). In addition to their use in warehousing and the corresponding internal inventory control, item numbers are also used at scanner checkouts, where they are read into the inventory management system in order to be able to record and invoice items when they are sold.

Person scanning a Barcode from a barrel in a warehouse. Author:
Scanners are often used coupled to mobile data terminals.Author TigerLily


Item numbers and the corresponding item number systems are used to clearly identify or classify items within or across companies. This makes it possible to rationalize the flow of goods between industry, trade and consumers and to control closed inventory management systems and make them more efficient. The most widely used item number is the EAN (European Article Number), which is applied to the product as a barcode by means of a label and is thus machine-readable. In the meantime, the EAN system and its North American counterpart UPC (Universal Product Code) have been merged to form GTIN, the Global Trade Item Number. Despite the change of term, the designation EAN is still used synonymously. With the GTIN, each product or product variant can be identified clearly and worldwide. It is used wherever products are subject to automatic registration and processing and have to be labeled. It forms a central component of inventory management and makes it possible to control supply and delivery processes in a systematic manner. Today, item numbers permeate the entire value chain, from warehousing and production to sales.

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