An ISO 639-3 code is a three-letter code that identifies one language, such as cym for Welsh. It is an international standard maintained by SIL International, and the code is shown on each language page of this map.
Key takeaways
- An ISO 639-3 code is a three-letter identifier for a language, maintained by SIL International as registration authority.
- Welsh is cym, Irish is gle and Maori is mri.
- A code names a language but says nothing about its family, area or number of speakers.
- Codes sometimes cover groups of related varieties, which the standard calls macrolanguages.
How ISO 639-3 codes work
ISO 639-3 is an international set of codes for identifying the world's languages. Each language gets a three-letter code, which gives programmers, librarians and researchers a name that does not change with spelling or translation. SIL International is the registration authority, called the Language Coding Agency for 639-3 [1]. It maintains the set through a change request process defined in the ISO 639 standard [1].
The standard grew out of earlier lists. The first code set, in 2007, combined ISO 639-2 with languages from SIL's Ethnologue and from the Linguist List [1]. This is why the codes are closely tied to the Ethnologue catalogue, though the standard is now administered separately from it [2].
A code is an identifier, not a definition. It does not record which family a language belongs to, where it is spoken, or how many people speak it. Different projects may also draw the line between two languages differently. The standard has code table entries that link macrolanguages to their members [1], and one example is Akan, treated by ISO as a macrolanguage containing Twi and Fante as separate languages [2].
An example from our data
Each language page on the map shows its code. Welsh is cym, Irish is gle and Maori is mri. Next to each is a Glottocode, the identifier from Glottolog: wels1247 for Welsh, iris1253 for Irish and maor1246 for Maori.
Using both makes it easier to match our pages to other datasets. The ISO code is the one most websites and software use, while the Glottocode is more tied to Glottolog's family tree. The data sources page names the datasets the map links.
The thing people get wrong
A common belief is that the code proves a variety is a language. It does not. A code is given to a variety by the standard's own process, and the decision can be argued, particularly for varieties that some regard as dialects. The map follows Glottolog and does not take a side.
Another mistake is to think the code is unique to a pair of languages across all systems. Older two-letter codes exist for some major languages, and other catalogues use their own identifiers, so always say which system a code belongs to. The map shows ISO 639-3 only where the code exists for a language.
Frequently asked questions
Who decides ISO 639-3 codes?
SIL International is the registration authority. It maintains the code set through a change request process defined in the ISO 639 standard.
Why does Welsh have a code starting with c when its English name starts with W?
Codes can come from the language's own name. Welsh is cym, from its Welsh name Cymraeg.
Sources
- ISO 639-3, SIL International (registration authority).
- Ethnologue, Wikipedia.
- Every figure from our own map is worked out from the datasets on the data sources page (checked against Glottolog and Glottography, retrieved 13 October 2026).