Learn · Level AAA · 31 criteria
Level AAA, and Why the Standard Tells You Not to Chase It
All 31 enhanced criteria, in plain language. These are reference rather than audit scope. No law we cover requires AAA, our reports test the 55 A and AA rules, and W3C says in the standard itself that AAA should not be required across a whole site. It also encourages authors to report progress on criteria beyond the level they claim, which is the sentence that makes taking these one at a time the right move.
What the standard actually says
It is not recommended that Level AAA conformance be required as a general policy for entire sites, because it is not possible to satisfy all Level AAA success criteria for some content. Sign language interpretation for every prerecorded video is the one that makes that plain. The reading level rule is gentler than its reputation, because a plain summary published beside a contract satisfies it and rewriting the contract never comes into it. W3C's own introduction goes further still. Even content conforming at AAA will not be accessible to people with all types, degrees and combinations of disability, particularly in the cognitive, language and learning areas. So aim at Level AA across the site and adopt individual AAA criteria where they are achievable, which our AA versus AAA guide works through.
The ones worth adopting anyway
Cheap, high-value, and achievable on most sites without redesigning anything.
- 1.4.6Contrast (Enhanced)Often a small darkening if you already clear 4.5:1
- 2.4.9Link Purpose (Link Only)Costs nothing at writing time, helps search too
- 2.2.5Re-authenticatingRemoves a near-absolute barrier on long forms
- 1.2.8Media AlternativeOne artefact that serves deafblind users and search
- 2.5.5Target Size (Enhanced)44 by 44, which Apple and Android already ask for
- 2.3.3Animation from InteractionsA few lines of CSS to honour reduced motion
Perceivable
Can everyone see, hear, or read your content? The A and AA rules under this principle.
- 1.2.6Level AAASign Language (Prerecorded)Prerecorded audio that runs synchronized with something else needs a sign language interpretation, and that sits on top of captions rather than replacing them.
- 1.2.7Level AAAExtended Audio Description (Prerecorded)Some videos leave no room for description.
- 1.2.8Level AAAMedia Alternative (Prerecorded)A media alternative is a text document carrying everything the video says and everything it shows, in the order it happens.
- 1.2.9Level AAAAudio-only (Live)Live audio with no picture needs a text alternative carrying the same information, available while the audio is running.
- 1.3.6Level AAAIdentify PurposeThe purpose of a component has to be identifiable in the code, not only visible on screen.
- 1.4.6Level AAAContrast (Enhanced)Body text needs a contrast ratio of at least 7:1, and large text at least 4.5:1, up from 4.5:1 and 3:1 at Level AA.
- 1.4.7Level AAALow or No Background AudioThis one covers prerecorded audio with no picture, so podcasts and audiobooks rather than video.
- 1.4.8Level AAAVisual PresentationThis one bundles five things about how a block of text is presented, and a block of text is anything more than one sentence.
- 1.4.9Level AAAImages of Text (No Exception)At Level AA you may use an image of text where the image can be visually customized to the reader's needs, and you may use one where the technology cannot achieve the presentation any other way.
Operable
Can everyone navigate and act, keyboard included? The A and AA rules under this principle.
- 2.1.3Level AAAKeyboard (No Exception)The Level A keyboard rule lets you off for functions where the path of the movement is the point, like freehand drawing.
- 2.2.3Level AAANo TimingThis rule removes time limits rather than making them adjustable.
- 2.2.4Level AAAInterruptionsAnything that interrupts the reader has to be postponable or suppressible, unless it involves an emergency.
- 2.2.5Level AAARe-authenticatingWhen an authenticated session ends, the user has to be able to log back in and carry on with their data intact.
- 2.2.6Level AAATimeoutsWarn people up front how long they can sit inactive before their data is lost.
- 2.3.2Level AAAThree FlashesNothing on the page may flash more than three times in any one second.
- 2.3.3Level AAAAnimation from InteractionsMotion an interaction sets off has to be possible to turn off, unless the animation is essential to the functionality or to the information it carries.
- 2.4.8Level AAALocationA reader has to be able to work out where they are inside a set of pages.
- 2.4.9Level AAALink Purpose (Link Only)Link text has to identify where the link goes, on its own, with no help from the sentence around it.
- 2.4.10Level AAASection HeadingsWhere content is organized into sections, those sections need headings.
- 2.4.12Level AAAFocus Not Obscured (Enhanced)When a component takes keyboard focus, no part of it may sit under anything you added to the page.
- 2.4.13Level AAAFocus AppearanceThe focus indicator has to be big enough and different enough to see.
- 2.5.5Level AAATarget Size (Enhanced)Pointer targets need to measure at least 44 by 44 CSS pixels, against 24 by 24 at Level AA.
- 2.5.6Level AAAConcurrent Input MechanismsContent must not restrict which input methods somebody can use, unless the restriction is essential, needed for the security of the content, or needed to respect the reader's own settings.
Understandable
Can everyone follow what things mean and do? The A and AA rules under this principle.
- 3.1.3Level AAAUnusual WordsWhere a word or phrase is used in an unusual or restricted way, the reader needs a way to find the definition you meant.
- 3.1.4Level AAAAbbreviationsEvery abbreviation needs its expanded form or its meaning available to the reader.
- 3.1.5Level AAAReading LevelWhere your text needs more reading ability than lower secondary education, you owe the reader either supplemental content or a simpler version.
- 3.1.6Level AAAPronunciationWhere a word's meaning is ambiguous unless you know how it is said, the reader needs a way to find the pronunciation.
- 3.2.5Level AAAChange on RequestChanges of context happen only when the reader asks for them, or a mechanism exists to turn such changes off.
- 3.3.5Level AAAHelpContext-sensitive help has to be available.
- 3.3.6Level AAAError Prevention (All)Where a page asks the reader to submit information, one of three things has to be true.
- 3.3.9Level AAAAccessible Authentication (Enhanced)A login step cannot require a cognitive function test unless that step offers either another authentication method that is not one, or a mechanism that helps the reader through it.
We test the 55 at Level A and AA.
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