Skip to main content

WCAG AAA in language I can understand

Posted in Accessibility

In this final part of my makes-sense-to-Martin summary of the Web Content Accessibility Guidelines (WCAG), I cover the often hard to meet AAA rules (success criteria); it follows on from my posts on WCAG 2.1 AA and WCAG 2.2.

Once again, there are a few things I need to point out before you dive in:

  • This a way for me to jog my memory, but hopefully it will help you get started understanding the intent of each success criterion
  • Almost everything is over-simplified; for a comprehensive explanation you’ve got WCAG itself
  • I haven’t covered why each criterion is helpful
  • There are very few examples


Time-based Media

1.2.6 Sign Language (Prerecorded)

All video that is published after video has sign language interpretation.

1.2.7 Extended Audio Description (Prerecorded)

Video is sometimes paused in order to give enough time for audio descriptions to be conveyed properly.

1.2.8 Media Alternative (Prerecorded)

A text-based transcription of a video is offered, on top of closed captions and audio description.

1.2.9 Audio-only (Live)

Live captioning is provided for live audio.


1.3.6 Identify Purpose

Landmark regions and personalisation semantics have been used, so people can use browser tools to do things like:

  • Remove non-essential content
  • Add identifying icons to particular elements on the page

1.4.6 Contrast (Enhanced)

Text has a contrast ratio of 7:1 to 1. Large text can be a 4.5 to 1 ratio if it’s over 24px, or bold and over 19px.


1.4.7 Low or No Background Audio

For spoken audio content, any background noise or music is 20 decibels lower than the foreground speech.

1.4.8 Visual Presentation

There’s a lot packed in this criterion, which covers blocks of text like paragraphs:

  • Never justify text
  • line-height must be at least 1.5
  • Width should be 80 characters max
  • Text and background colours can be set by the user (usually via a custom stylesheet)

1.4.9 Images of Text (No Exception)

Text is actual text; never images of text.


Keyboard Accessible

2.1.3 Keyboard (No Exception)

You can navigate and interact with a page using the keyboard alone.

Enough Time

2.2.3 No Timing

Unless it’s a live broadcast or something else that’s happening in real time, there are no time constraints placed on the user.

2.2.4 Interruptions

Pop-ups, notifications, and other interruptions can be switched off.

2.2.5 Re-authenticating

If a logged-in session expires mid-way through a task, any data entered after expiry is kept, so that they don’t have to re-enter it when they log in again.

2.2.6 Timeouts

A warning is shown if a logged-in session is about to expire.

Seizures and Physical Reactions

2.3.2 Three Flashes

Nothing flashes, blinks, or flickers more than three times in one second.

2.3.3 Animation from Interactions

Animations triggered by interactions like button presses can be turned off.

2.4.8 Location

The user is clearly informed where they are in a set of pages.

It is clear where a link will take you from the link text alone, without having to read the text around it.

2.4.10 Section Headings

Headings are used to group distinct sections on a page.

Input Modalities

2.5.5 Target Size

Anything clickable should be at least 44 by 44 pixels, except links within a sentence which are okay to be the size of the text they encompass.

2.5.6 Concurrent Input Mechanisms

The user can happily switch between using a mouse, touchscreen, keyboard, or any other input device.



3.1.3 Unusual Words

Jargon and figurative language is avoided, or, where not it’s possible, the words are defined or clarified the first time they’re used on a page.

3.1.4 Abbreviations

Acronyms and shortened words are avoided; where not that’s possible, a definition are provided on each page they’re used.

3.1.5 Reading Level

Writing is kept relatively simple, and is able to be understood by primary school children.

3.1.6 Pronunciation

If a word can be pronounced more than one way, and each way has a different meaning, the meaning is clarified to avoid ambiguity.


3.2.5 Change on Request

Nothing in the user interfaces changes without the user expressly requesting it using a <button>.

Input Assistance

3.3.5 Help

Where a label can’t provide enough information to understand what’s being asked, there’s hint text or some other kind of explanation alongside.

3.3.6 Error Prevention (All)

After entering any information, the user is offered the opportunity to check it before sending.

Accessibility in your inbox

I send an accessibility-centric newsletter on the last day of every month, containing:

  • A roundup of the articles I’ve posted
  • A hot pick from my archives
  • Some interesting posts from around the web

I don’t collect any data on when, where or if people open the emails I send them. Your email will only be used to send you newsletters and will never be passed on. You can unsubscribe at any time.

More posts

Here are a couple more posts for you to enjoy. If that’s not enough, have a look at the full list.

  1. Bag some AAA wins where you can

    Complying with WCAG AA is hard, and AAA seems a lot harder, but there are actually plenty of AAA rules that are relatively easy to meet.

  2. WCAG, but in language I can understand

    An as-close-to-a-single-paragraph-as-I-can-manage summary of each rule in the Web Content Accessibility Guidelines, version 2.1, level AA.