What is the difference between ISO 639-1 and ISO 639-2?

ISO 639-1 assigns two-letter codes to about 184 major languages, while ISO 639-2 assigns three-letter codes that cover several hundred languages, including many with no two-letter code. Use 639-1 where it exists for brevity and fall back to 639-2 for full coverage.

Which code does an HTML lang attribute use?

HTML lang attributes use BCP 47 tags, which start with the ISO 639-1 two-letter code where one exists, such as lang="en" or lang="fr". For languages without a two-letter code, the three-letter 639-2 code is used instead, and a region subtag like en-GB can be appended.

What does the 639-2/T variant mean?

Some languages have two three-letter codes in ISO 639-2: a bibliographic (B) code and a terminology (T) code. This tool lists the terminology variant, such as deu for German rather than the bibliographic ger, because the T codes align with ISO 639-3 and modern software.

Why do some languages show a dash in the two-letter column?

A dash means the language has no ISO 639-1 two-letter code, which is common for less widely used languages. In that case you must use the three-letter ISO 639-2 code, since there is no shorter standard alternative.

Are these codes the same as locale identifiers?

Not exactly. A locale combines a language code with a region and optional script, like en-US or zh-Hans-CN. The language portion comes from ISO 639, so this lookup gives you the first and most important part of a locale string.

ISO 639 Language Code Lookup

Email me this result

Get this tool's output sent to your inbox, plus one useful tool a week. No spam, unsubscribe any time.

What this tool is for

This reference lets you find the standard language codes that software, web pages, and translation APIs use to identify a language. It covers both ISO 639-1 two-letter codes and ISO 639-2 three-letter codes, with native names so you can confirm you have the right language.

How it works

Each language carries two codes. ISO 639-1 is a compact two-letter set covering the most widely used languages, and it is what HTML lang attributes and most browser and translation APIs expect. ISO 639-2 is a broader three-letter set that includes languages with no two-letter code, so it is the fallback when 639-1 falls short.

The tool matches your query against the English name, the native name, and both codes. Typing fr, fra, French, or Français all resolve to the same row. Where a language has no two-letter code, the 639-1 column shows a dash and you should use the three-letter code instead.

Tips and notes

For web markup, prefer the shortest valid code: use the two-letter 639-1 code when one exists and append a region subtag only when you need to distinguish variants, as in en-GB versus en-US. The three-letter codes shown here are the 639-2/T (terminology) variants, which line up with ISO 639-3 and avoid the older bibliographic codes like ger and fre.