GS1-128 Basics

A GS1-128 barcode is used on shippers, cases, pallets where extra information (expiry date, batch number etc) IS required to be encoded into the barcode

For the required dimensions / specifications click here


  • Application Identifiers (AI) are used to indicate the information encoded e.g. AI (17) indicates the Expiry Date
  • Decide what information is to be encoded
  • Place an appropriate AI (Application Identifier) at the front of the GTIN (barcode number)

         (00) for SSCC (Serial Shipping Container Code e.g Pallets)

         (01) for GTIN (most common)

         (02) For GTIN of Contained Trade Items 

    •  The GTIN must be 14 digits

Note:   For fixed weight units use an indicator between 0 - 8 only.

            For variable measure units use indicator digit ‘9’ only

 Ensure that the appropriate AI is inserted at the start of each piece of data.

(17) Expiry Date  

(10) Batch Number

 Note:  Dates MUST be YYMMDD i.e. 190304 (04 March 2019)

  • Organise the information so that all fixed-length data is encoded together and before any variable-length data

(17) Expiry Date is fixed length data

(10) Batch Number is variable length data

  •  A total of 48 symbol charters can be used (made up of digits, letters, start/stop and function 1 charters NOT brackets)

Variable measure product

If using a variable measure GS1-128 ensure Indicator digit "9" and AI 310(***) are used together


Commonly Used Application Identifiers (AIs), for a full list click here 



(*): The first position indicates the length (number of digits) of the GS1 Application Identifier. The following value refers to the format of the data content. The following convention is applied:

  • N numeric digit
  • X any character
  • N3 3 numeric digits, fixed length
  • ..3 up to 3 numeric digits
  • ..3 up to 3 characters

(**):  If only year and month are available, DD must be filled with two zeroes.

(***): The fourth digit of this GS1 Application Identifier indicates the implied decimal point position.


  • 3100 Net weight in kg without a decimal point
  • 3102 Net weight in kg with two decimal points

(****):  All GS1 Application Identifiers indicated with (FNC1) are defined as of variable length and shall be delimited unless this Element String is the last one to be encoded in the symbol. The delimiter shall be a Function 1 Symbol Character in GS1-128 Symbology.

Version1.0 14 Feb 2020







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