WCAG has three conformance levels and they are cumulative. A is the floor, and failing these blocks people outright. AA adds the rules that make a site genuinely usable, and it is the level laws and contracts name. AAA is enhanced.
At WCAG 2.2 that is 31 criteria at Level A, 24 more at AA for 55 combined, and 31 enhanced criteria at AAA. Eighty-six in total. Level A and Level AAA both landing on 31 is a coincidence and it is the reason those two numbers get swapped in half the summaries you will read.
One precision about the level, because it comes up in procurement. The level is consistently AA across the laws that name a standard. The version is not consistent at all. Section 508 incorporates WCAG 2.0. The DOJ's Title II rule names WCAG 2.1. EN 301 549 in force names WCAG 2.1. So "we target AA" is an incomplete answer, and "we target WCAG 2.2 Level AA" is a complete one that covers all three.
What AAA Actually Adds
| Requirement | At Level AA (which includes A) | Level AAA |
|---|---|---|
| Text contrast | 4.5:1 | 7:1 |
| Large text contrast | 3:1 | 4.5:1 |
| Sign language for video | Not required | Required for prerecorded audio in video |
| Extended audio description | Not required | Required where the pauses in the audio are too short |
| Reading level | Not required | Lower secondary level, or a simpler version alongside |
| Link purpose | Clear in context | Clear from the link text alone, unless it would be ambiguous to everyone |
| Timing | Adjustable | No time limits at all, apart from live events and non-interactive media |
| Keyboard | Every function except path-dependent input | Every function, no exception |
Two of those rows carry a detail the short version usually loses. The sign language rule reaches prerecorded audio inside synchronized media, which means video with sound. A podcast is audio-only, so it is not in scope for it at all. And the link rule has an exception for links whose purpose would be unclear to any reader, disabled or not, which stops it becoming an impossible standard for genuinely ambiguous destinations.
Why W3C Advises Against Requiring It
The standard says so itself, in the conformance section. Level AAA conformance is not recommended as a general policy for entire sites, because it is not possible to satisfy every AAA criterion for some content.
Be exact about the weight that sentence carries, because it is the kind of thing somebody will check. It is a note, and W3C states plainly that notes are informative rather than normative, so it creates no requirement and nobody has ever failed an audit for aiming at AAA. What it is, is W3C's own published advice sitting inside the conformance section of its own standard. That is the strongest form this argument comes in, and it is still advice.
W3C never published a list of which criteria are the impossible ones, so anybody naming specific examples is exercising judgment, ourselves included. Here is ours. Keyboard operation is the sharpest case. At AA you can except a function that genuinely needs path-dependent input, and at AAA that exception is gone, so a freehand drawing canvas cannot conform at AAA however carefully it is built. Sign language is the expensive case rather than the impossible one. For a site with two hundred videos it is a large ongoing cost, and for a site publishing daily it stops being achievable in practice.
There is a structural reason underneath both examples, and it is countable. Eight of the 31 AAA criteria sit under the guidelines covering time-based media and readable text, four in each, which are the two areas where the cost is content production rather than engineering. You can pay a developer once to fix a focus indicator. You pay for sign language interpretation on every video you ever publish.
The practical risk
Writing AAA into a policy or a contract commits you to something you will fail. That is worse than committing to AA and meeting it, because a published claim you do not meet is a documented gap rather than an aspiration, and it is the first thing anybody investigating you will read.
What to Do Instead
Target AA across the site, and adopt individual AAA criteria where they are achievable and worth something to your audience. That is the arrangement the standard is built for, and it goes further than tolerating it. The conformance section positively encourages you to report progress towards criteria beyond the level you claim, inside the claim itself. So the effort is not invisible and you do not have to pretend it did not happen.
Good candidates to adopt selectively:
- 7:1 contrast on body text. Worth checking rather than assuming, because 4.5:1 to 7:1 is a bigger step in luminance than it looks and a brand colour sitting at 5:1 does not get there by rounding. On white, the lightest grey that clears 7:1 is #595959.
- Link text that works on its own, without the sentence around it. Better for everyone, and it happens to be what search engines and screen reader link lists both want.
- A plain-language summary beside your densest pages. The reading level criterion is met by a simpler version being available, so the contract or the technical spec stays exactly as it is and nobody has to dumb anything down.
- No time limits, unless a genuine constraint requires one, which for most sites is almost never.
- Section headings used to organise your content, which is mostly good structure anyway and costs nothing at authoring time.
Three Conformance Rules That Catch People Out
Before anybody claims a level anywhere, three requirements in the same section decide whether the claim survives contact with a reader.
Conformance belongs to whole pages. It cannot be achieved if part of a page is left out, so there is no such thing as conforming apart from the bit you would rather not talk about.
Every responsive variation counts separately. Where a page presents a different layout at a different screen size, each of those variations has to conform for the page to conform. Your mobile layout is not covered by the desktop one having passed.
A process is only as conformant as its worst page. Where a page is one of a series making up a process, every page in that process has to conform at the level claimed. W3C's own worked example is a shop checkout, which is exactly where this bites hardest.
There is a relief valve attached to the first of those, and hardly anybody uses it. Where a page cannot conform because of content you do not control, the standard points you at a Statement of Partial Conformance, which lets you describe honestly what conforms and what does not rather than claiming nothing or claiming too much.
One honest limit
Conformance is claimed at a level for a page. A page meeting some AAA criteria but not all of them conforms at AA, not at AAA, and saying otherwise in an accessibility statement is a claim that will not survive checking. Exceeding AA is worth doing, worth reporting, and does not change the level you can claim.