WCAG 1.2.6 Sign Language: Adding Sign Language Interpretation to Videos

Level AAA Perceivable WCAG 1.2.6

What This Criterion Requires

WCAG 1.2.6 requires that sign language interpretation is provided for all prerecorded audio content in synchronized media. While captions provide a text-based alternative for deaf users, many people who are deaf from birth or early childhood consider sign language their primary language and may find captions difficult to follow, especially for complex or fast-paced content. Sign language conveys tone, emphasis, and emotional nuance in ways that text alone cannot. This criterion applies to videos, webinars, recorded presentations, and any other synchronized media with an audio track. The sign language interpreter should be clearly visible, properly lit, and large enough to read facial expressions and hand movements. Picture-in-picture overlays and dedicated sign language video tracks are both acceptable approaches. Meeting this AAA criterion demonstrates a deep commitment to inclusive communication and benefits a significant population of deaf and hard-of-hearing users who prefer visual language over written text.

Why It Matters

For many people who are born deaf, sign language is not just an alternative to spoken language but their native language. Written text, including captions, functions as a second language that may be less natural and harder to process, particularly for lengthy or complex content. Research consistently shows that deaf sign language users comprehend information more accurately and quickly when presented in sign language compared to written text. Videos about healthcare, legal rights, emergency procedures, and educational material are especially critical to provide in sign language because misunderstandings can have serious consequences. Additionally, sign language conveys emotional tone, sarcasm, urgency, and other paralinguistic features that captions flatten into plain text. Organizations that provide sign language interpretation for their video content create a genuinely inclusive experience rather than relying solely on text-based accommodations. This criterion is particularly relevant for government agencies, healthcare providers, and educational institutions that serve diverse deaf communities.

Common Failures and How to Fix Them

No sign language interpretation provided for video content

Prerecorded videos include only captions and audio descriptions but no sign language interpretation. Users whose primary language is sign language must rely entirely on text captions that may not fully convey the meaning.

Inaccessible 
<video controls>
  <source src="training-video.mp4" type="video/mp4">
  <track kind="captions" src="captions.vtt" srclang="en">
</video>
Accessible 
<video controls>
  <source src="training-video.mp4" type="video/mp4">
  <track kind="captions" src="captions.vtt" srclang="en">
</video>
<p><a href="training-video-asl.mp4">Watch with ASL interpretation</a></p>

Sign language interpreter is too small or poorly lit

A sign language interpreter is included as a picture-in-picture overlay, but the window is too small to read hand shapes and facial expressions clearly, or lighting makes the interpreter difficult to see.

Inaccessible 
<!-- PiP overlay at 10% of video area, dark background -->
<div style="position:absolute; bottom:0; right:0; width:10%; opacity:0.8">
  <video src="interpreter.mp4"></video>
</div>
Accessible 
<!-- PiP overlay at minimum 25% of video area, well-lit -->
<div style="position:absolute; bottom:8px; right:8px; width:25%; background:#fff">
  <video src="interpreter.mp4" autoplay muted></video>
</div>

Sign language version not discoverable

A sign language version of the video exists but there is no visible link or toggle to access it. Users must know the URL or navigate away from the main content to find it.

Inaccessible 
<!-- ASL version exists at /videos/asl/ but no link on page -->
<video src="presentation.mp4" controls></video>
Accessible 
<video src="presentation.mp4" controls></video>
<nav aria-label="Video format options">
  <button aria-pressed="false" onclick="toggleASL()">Show ASL Interpreter</button>
  <a href="presentation-asl.mp4">Download ASL version</a>
</nav>

How to Test

  1. Identify all prerecorded video content on the page that includes an audio track with spoken information.
  2. Verify that each video has a sign language interpretation option, either embedded as a picture-in-picture overlay or available as a separate video track.
  3. Check that the sign language interpreter is clearly visible, well-lit, and large enough to read facial expressions and hand movements.
  4. Confirm that the sign language interpretation is synchronized with the audio content and covers all spoken information.
  5. Verify that users can easily discover and access the sign language version through visible links, buttons, or toggles.

CMS-Specific Guidance

This criterion commonly causes issues on these platforms:

Further Reading

Related WCAG Criteria