lang attribute must have a valid value

Rule ID: valid-lang
Ruleset: axe-core 4.7
User Impact: Serious
Guidelines: WCAG 2.1 (AA), WCAG 2.0 (AA), Trusted Tester

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Compliance Data & Impact

User Impact


Disabilities Affected

  • Blind
  • Deafblind
  • Cognitive


  • WCAG 2.1 (AA)
  • WCAG 2.0 (AA)
  • Trusted Tester

WCAG Success Criteria [WCAG 2.1 (AA)]

  • 3.1.2: MUST: Language of Parts

WCAG Success Criteria [WCAG 2.0 (AA)]

  • 3.1.2: MUST: Language of Parts

Trusted Tester Guidelines

  • 11.B: MUST: The human language for any content segment that differs from the default human language of the page can be programmatically determined.

How to Fix the Problem

Ensure that the language code specified in the lang attribute is a valid language code (e.g. <html lang="en"> would set the language of the document to English).

Make sure you identify a language in the opening <html> element and spell the attribute correctly. For example, if the primary language of a document is English, you could specify the language as follows:

<html lang="en">
    document text

If you would like, you can even specify some dialects with codes such as "en-US" to signify American English or "fr-CA" for Canadian French. You can find a list of language and dialect codes on the internet.

If the language changes within a document, you can specify this as follows:

<p>Text in one language <span lang="es">text in another language</span></p>

If you are using a language that is written right to left, be sure to specify this using the dir attribute:

<p lang="ar" dir="rtl">Arabic text here</p>

If you would like to specify that a language is written left to right, you can fill the value of the dir attribute with the value "ltr".

Ensure that the language code specified in the <html lang=" "> is a valid and allowed language code.

To identify the primary language of the document as English in the opening <html> element, designate it with the two-letter code "en".

<html lang="en">   

Language value codes include some dialects such as "en-US" to differentiate American English from UK English< or "fr-CA" to differentiate Canadian French from European French. You can find a list of language and dialect codes on the ISO Codes for the Representation of Names of Languages web page.

Why it Matters

When configuring a screen reader, users select a default language. If the language of a webpage is not specified, the screen reader assumes it is the default language set by the user. Language selection becomes an issue for users who speak multiple languages and access the website in more than one language. It is essential to specify a language and ensure that it is valid so website text is pronounced correctly.

Screen readers use different sound libraries for each language, based on the pronunciation and characteristics of that language. Screen readers can switch between these language libraries easily, but only if the documents specify which language(s) to read. If the language is not specified, the screen reader reads the document in the user's default language, resulting in a confusing experience!

Rule Description

The language specified in the HTML document must be one of the valid languages to ensure text is pronounced correctly for screen reader users.

The Algorithm (in simple terms)

lang attribute must have a valid value.


Other Resources

You may also want to check out these other resources.

Refer to the complete list of axe 4.7 rules.

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