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WCAG levels A, AA, and AAA explained

What WCAG levels A, AA, and AAA mean, which one the law asks for, and why AAA is not a whole-site target. A plain guide to conformance levels.

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Pavel Charkasau

WCAG sorts every success criterion into one of three conformance levels: A, AA, and AAA. Level A is the floor, AA is the middle, and AAA is the strictest. The levels stack. To claim AA conformance a page has to meet every Level A criterion and every Level AA criterion; to claim AAA it has to meet all three sets (W3C, Understanding Conformance). For almost everyone the target that matters is AA, because that is the level written into accessibility law across the EU and the US. AAA is not meant to be a whole-site goal, and the W3C says so directly. This guide explains what each level covers, how a criterion ends up at one level or another, which level your obligation names, and how to check where a page actually stands.

What do WCAG levels A, AA, and AAA mean?

The three levels are a way of grading how much each success criterion matters and how achievable it is across the whole web. Level A collects the criteria that are essential: if you miss one, some people simply cannot use the content, and no assistive technology can rescue it. Keyboard operation (2.1.1) and text alternatives for images (1.1.1) live here. Level AA adds the criteria that remove the next tier of common barriers, such as a 4.5:1 contrast ratio for normal text (1.4.3) and a visible keyboard focus indicator (2.4.7). Level AAA holds the strictest requirements, like a 7:1 contrast ratio (1.4.6) or sign-language interpretation for prerecorded audio (1.2.6) (W3C, WCAG 2.2).

Conformance is cumulative, and that trips people up. There is no such thing as "AA but not A". Meeting AA means you have already met every A criterion underneath it. WCAG 2.2 has 86 success criteria in total: 31 at Level A, 24 more at AA, and 31 at AAA (W3C, What's New in WCAG 2.2). So an AA claim covers 55 of them, and an AAA claim covers all 86.

How is a success criterion assigned to a level?

The working group did not sort criteria by how hard they are to code. They weighed a few things together (W3C, Understanding Conformance):

  • Whether the criterion is essential — if it is not met, even assistive technology cannot make the content usable.
  • Whether it is possible to satisfy it for all websites and content types it would apply to.
  • Whether a content creator could reasonably learn to meet it, roughly within a week of training.
  • Whether it would put hard limits on the look, feel, or function of the page.

A criterion that is essential, broadly achievable, and light on design constraints tends to land at A. One that helps a lot but cannot be met on every kind of content, or that constrains design more, tends to land at AAA. Contrast is the clearest example. A 4.5:1 ratio is achievable on essentially any interface, so it sits at AA. The stricter 7:1 ratio rules out a lot of legitimate brand palettes, so it sits at AAA. The level is a judgement about breadth and cost, not a measure of how much a given user needs it.

What is the difference between A, AA, and AAA in practice?

Here is the same idea with real criteria, one column per level. These are examples, not the full lists.

ConcernLevel ALevel AALevel AAA
Text contrast—4.5:1 for normal text (1.4.3)7:1 for normal text (1.4.6)
VideoCaptions for prerecorded video (1.2.2)Captions for live video (1.2.4)Sign language for prerecorded video (1.2.6)
KeyboardAll function available from a keyboard (2.1.1)Focus is visible (2.4.7)Keyboard operation with no timing (2.1.3)
NavigationA way to skip repeated blocks (2.4.1)Multiple ways to find a page (2.4.5)Link purpose clear from the link text alone (2.4.9)
Reading——Content readable at lower-secondary level (3.1.5)

Two patterns show up. Level A and AA criteria can be met on most sites without redesigning the product. Several AAA criteria cannot: you can add captions to every video, but writing all your content at a lower-secondary reading level is not possible for a legal contract or a research paper. That gap is exactly why AAA is not a site-wide target.

Which WCAG level do you legally need?

For nearly every regulation, the answer is AA. WCAG itself is not a law; it is a technical standard that laws and contracts point to, and they consistently point at Level AA:

  • European Union. The harmonised standard EN 301 549, in its current version v3.2.1, adopts WCAG 2.1 Level AA for web content (ETSI EN 301 549 v3.2.1). The European Accessibility Act relies on that standard, so AA is the working target across the EU.
  • US state and local government. The US Department of Justice's 2024 ADA Title II rule sets WCAG 2.1 Level AA as the technical standard (ADA.gov). See ADA for how that fits the wider act.
  • US federal government. Section 508 incorporates WCAG 2.0 Level AA through its Revised Standards.

I have never seen a mainstream accessibility law require AAA across a whole site, and given the reading-level and contrast criteria above, I would be surprised to. When a contract or an RFP says "WCAG conformance" without a level, assume it means AA and confirm in writing. AA is the number that shows up in an audit.

Why isn't AAA the goal?

Because the W3C designed it not to be. The spec states it plainly: "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" (W3C, Understanding Conformance).

That does not make AAA useless. It is a menu. Pick the AAA criteria that fit your audience and apply them where they help. A government service aimed at a wide public might adopt 1.4.6 Contrast (Enhanced) and 2.2.6 Timeouts even while it conforms to AA overall. A media site might adopt 1.2.6 Sign Language on key content. The honest way to describe that is "AA conformant, with selected AAA criteria met", not "AAA". Claiming full AAA for an entire site is usually a claim you cannot actually stand behind.

How do you check which level your site meets?

Start with an automated scan to clear the mechanical failures, then test by hand for the criteria a machine cannot judge. A scanner reliably checks things like contrast ratios, missing alt attributes, and form labels. It cannot tell you whether your alt text is meaningful, whether the reading order makes sense to a screen reader, or whether a drag interaction has a real keyboard path. Automated tools catch roughly 30 to 57% of issues; the rest needs a person with a keyboard and a screen reader (Deque, 2021). A clean scan is the start of the review, not the end.

Our WCAG checklist lists the criteria by level, so you can see which ones apply to an AA target and which are AAA. For the single most common failure, run your palette through the contrast checker — 1.4.3 at AA is the criterion sites fail most often.

Frequently asked questions

Is WCAG AA the same as AAA?

No. AA and AAA are separate conformance levels. AAA is stricter and includes everything in A and AA plus its own criteria, such as a 7:1 text contrast ratio instead of 4.5:1 (W3C, WCAG 2.2). Meeting AAA means meeting all three levels; meeting AA does not require the AAA criteria.

Which WCAG level is required by law?

Level AA in almost every case. EN 301 549 and the DOJ's ADA Title II rule both name WCAG 2.1 Level AA, and Section 508 names WCAG 2.0 Level AA (ETSI EN 301 549 v3.2.1; ADA.gov).

Do I need to meet Level A separately if I target AA?

No, and you cannot avoid it. Conformance is cumulative: an AA claim already requires meeting every Level A criterion. There is no valid "AA without A" (W3C, Understanding Conformance).

Why doesn't the W3C recommend AAA for whole sites?

Because some AAA criteria cannot be met for some content. The W3C states that AAA should not be required as a general policy for an entire site, since it is not always possible to satisfy every AAA criterion (W3C, Understanding Conformance).

How many WCAG success criteria are there per level?

WCAG 2.2 has 86 in total: 31 at Level A, 24 more at Level AA, and 31 at AAA. An AA claim therefore covers 55 criteria; an AAA claim covers all 86 (W3C, What's New in WCAG 2.2).

See which level your pages meet

The levels only mean something once you measure a real page against them. Run a free scan to get the violation list with the exact selector for each issue, sorted so you can see which failures sit at A and AA — the levels your obligation names. Then bring in a manual review for the criteria a scanner cannot judge. Automation finds the mechanical problems fast; full conformance still needs a human to confirm the rest.

Written by Pavel Charkasau, founder of wcagc.com. Last updated 23 July 2026.

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