Frequently asked questions

What is a GTIN?

GTIN stands for a Global Trade Item Number. It is a standard that was developed by the international organization GS1 to be used to look up product information and match products across databases of various counter agents (retailers, manufacturers, etc).

What information is encoded in GTIN?

First three digits of GTIN (in the 13-digit format) encode a country of origin with a so-called Unique Country Code (UCC). Following 6 to 9 digits encode a so-called Company Prefix1. This number is assigned to a company and therefore remains constant in any GTIN number owned by this company (a purchaser of codes). Remaining digits up to and including the penultimate are the product number assigned to an item2 chosen by the purchaser. The last digit in GTIN is called a checksum digit, which is used to verify the correctness of the GTIN and is calculated as the standard modulo 10 of previous digits.

How do GTIN and EAN/UPC/ISBN relate?

Long story short, UPC, EAN and ISBN are all GTINs of different formats. The subsets of GTIN are:

  • UPC - Universal Product Code (UPC-A, 1970)
  • EAN - European Article Number also known as International Article Number - a superset of the original 12-digit UPC-A standard. EAN-8 barcode was introduced for use on small packages
  • ISBN - International Standard Book Number. Originally developed as a 10-digit code (ISBN-10, ISO 2108, 1970). Since 2007, ISBN code has been expanded to 13-digits, a format that is compatible with Bookland3 EANs. In order to convert ISBN-10 into ISBN-13 format one should perform the following permutations: drop the last digit, prepend the code with Bookland's UCC (978), calculate a new check digit and tack it on to the end

GTIN incorporates all aforementioned standards into a universal number space:

  • GTIN-8 - corresponds to EAN-8
  • GTIN-12 - corresponds to UPC
  • GTIN-13 - corresponds to EAN-13/ISBN-13. Converting GTIN-12 into GTIN-13 is rather straightforward - one has to prepend GTIN-12 code with 0
  • GTIN-14 - is used for wholesale shipments and therefore is not included in our database

Does ASIN conform to the GS1 standard for GTIN?

No, albeit it stems from ISBN-10 identifiers (Amazon started as a book reseller, remember?), ASIN (for Amazon Standard Identification Number) is developed as a proprietary alphanumeric unique product identifier for Amazon's internal use and can not be converted into GTIN, with the exclusion for printed books, for which their ASIN is equal to their ISBN-10 code.

1 One can lookup company codes in the Global Electronic Party Information Register (GEPIR®) maintained by GS1. It contains basic information on over 1,000,000 companies in over 100 countries.
2 An item can be a group of product variations (a model of different sizes and colours) or a unique variation. There is no strict rule, therefore the choice of numbering strategy is up to a purchaser. However, for ease of administration, it is recommended that purchasers maintain item numbers in a sequence.
3 Bookland is an informal reference to a fictitious UCC (978) created for the purpose of non-geographical book cataloguing in otherwise geographically keyed EAN number space.