What is an ISO Language Code?

17th December 2014

Emily Robertshaw

ISO Code

The first standardised language code system ISO 639, was introduced by the International Organisation for Standardisation with the aim of representing language and language groups. The main purpose for creating these codes was to ensure that languages and language families, could be recognised internationally regardless of a person’s native language. 

The ISO 639 codes now consist of 6 parts and are either 2, 3 or 4 letters long depending on which ISO code is used. 


Where would you use ISO codes?

Using ISO codes to represent languages, allows for easier referencing across the world. The standardisation of languages is used for bibliographical referencing in libraries whilst also having a great use in modern technology. Websites use ISO codes to represent different language versions of a website. This allows websites to create different language versions that are optimised for different locations/languages, and display those based on the location of the user. 


Different types of ISO code

ISO 639-1  – This is the Alpha-2 code. This was the first ISO code created and features a two letter code to represent a language. There are 136 IS0 639-1 codes representing languages all over the world. Examples of ISO 639-1 codes include:




We have also created a handy ISO-639-1 guide, which features a more comprehensive list!

ISO 639-2  – This is a 3 letter code. The 3 letter code offers more possible language combinations and there are 464 codes. The ISO 639-2 coding system was developed as a result of the first ISO coding system not allowing for the formation of groups of languages. This coding system allows for grouping of collective languages; for example:


CodeLanguage Group
batBaltic Languages
celCeltic Languages
gemGermanic Languages
korKorean Languages


ISO 639-3 – Like the ISO 639-2, the ISO 639-3 code system is also made up of 3 letters, however this coding system also includes extinct and ancient languages as well as languages still around today. This code doesn’t take into consideration ‘group’ languages, which has led to many codes in ISO 1 and 2 being referred to as ‘macro-languages’ which can be seen to have been broken down into micro languages in ISO 3. This coding system has helped to address the issue of the digital divide, allowing for more languages to be optimised for the web and giving more opportunity for languages to be included online.

ISO 639-4 –  This refers to the general principles of language coding and presents guidelines for using the ISO 639 codes.

ISO 639-5 – This code provides a 3 letter reference for language families and groups. This code further expands on the grouping carried out in ISO 639-2.

ISO 639-6 – This is the most recent coding system developed by the ISO and is a 4 letter code that allows us to distinguish between variants of languages and language families. This is the most comprehensive code and attempts to distinguish between as many enumerations of languages as possible including extinct, living, ancient, major, minor languages and even includes all written, spoken and signed languages. The ISO 6 system establishes a hierarchical framework which allows us to create a historical timeline of languages as the code links each language to its principle ancestor. For example;


engEnglish Language
emenEarly Modern English
emseEarly Midland and South Eastern Middle English
mengeMiddle English
angoAnglo Saxon
nseaNorth Sea
gmcwGermanic West


As you can see, this list is far more granular and as a result, over 21,000 codes exist! 

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