Foundations

WCAG Conformance Levels: A, AA, and AAA Explained

Every WCAG success criterion is assigned one of three conformance levels — A, AA, or AAA — from least to most strict. Conforming to a level means meeting every criterion at that level and every criterion at the level(s) below it. There's no such thing as "AA without A" — AA conformance is A conformance plus the additional AA criteria.

Level A — the essential minimum

The baseline. Level A criteria address barriers so severe that some users would be completely blocked without them — no keyboard access at all, no text alternative for images, no way to tell what a form field is for. WCAG 2.2 has 31 Level A criteria. Meeting only Level A is rarely considered acceptable for legal or procurement purposes; it's treated as a floor, not a target.

Level AA — the practical, legally-referenced target

Level AA adds 24 more criteria addressing broader, still-common barriers: insufficient color contrast, content that doesn't reflow on mobile, inconsistent navigation across a site. AA is the common technical target, but the legal route differs by regime: ADA Title II names WCAG 2.1 AA, Revised Section 508 incorporates WCAG 2.0 A/AA, and many procurement questionnaires ask for an AA evaluation. The European Accessibility Act instead states functional requirements and does not directly adopt a WCAG level; WCAG and EN 301 549 remain important technical guidance. When AllyProof says "WCAG 2.2 AA," it means the scan target of all 55 active A + AA criteria, not a claim that every law directly requires that version.

Level AAA — the highest bar, rarely required in full

AAA adds the most stringent requirements: enhanced 7:1 color contrast, sign language interpretation for prerecorded video, reading-level restrictions on text. WCAG's own documentation explicitly states that it is not recommended as a general policy requirement for entire sites, because some AAA criteria are genuinely impossible to satisfy for certain types of content (a legal contract can't simultaneously be legally precise and written at a lower reading level, for instance). Organizations typically cherry-pick individual AAA criteria where practical rather than committing to full AAA conformance.

Why AA is the number that matters

If you take one thing from this page: AA is the practical engineering target, but the applicable version and legal obligation depend on the jurisdiction and context. AllyProof scans against WCAG 2.2 AA as the current technical target. See Is WCAG a Law? for which regulations cite a particular version and level, and WCAG Versions Explained for how the version number (2.0 / 2.1 / 2.2) interacts with the level.

Common questions

What is the difference between WCAG A, AA, and AAA?

They are increasing levels of strictness. Level A covers the most basic barriers, AA adds criteria commonly referenced by accessibility rules and procurement programs, and AAA is the most demanding. Meeting a level requires meeting it and every level beneath it.

Which WCAG level should I aim for?

Level AA is the common engineering target. ADA Title II requires WCAG 2.1 AA and Revised Section 508 incorporates WCAG 2.0 A/AA. The EAA states functional requirements rather than directly adopting a WCAG level, though WCAG and EN 301 549 are important technical guidance.

Why isn't AAA the goal?

WCAG itself states that AAA conformance is not recommended as a blanket policy for whole sites, because some AAA criteria cannot be met for all content. Teams apply AAA selectively where it helps most.