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Best Practice

WCAG Conformance Levels Explained

A clear explanation of WCAG A, AA, and AAA conformance levels — what each level covers, what the law requires, and how to plan your conformance target.

What Are WCAG Conformance Levels

The Web Content Accessibility Guidelines (WCAG) organize their 87 success criteria into three conformance levels: A (most basic), AA (standard), and AAA (highest). These levels reflect the impact on users and the feasibility of implementation. Level A criteria represent barriers so severe that they block access for entire groups of users. Level AA criteria address the most significant remaining barriers. Level AAA criteria provide enhanced accessibility for specific user groups and are not always achievable for all content types.

Conformance is binary: a page either meets a criterion or it does not. There is no partial credit. A site claiming "WCAG 2.2 AA conformance" means every page on the site meets all Level A and AA criteria.

Level A: The Baseline

WCAG 2.2 contains 30 Level A success criteria. These represent the absolute minimum — failing any one of them creates a barrier that completely blocks access for at least one user group. Level A failures are typically severe: missing alt text on images (blocks blind users), keyboard inaccessibility (blocks keyboard-only users), no captions on video (blocks deaf users).

Notable Level A criteria include: 1.1.1 Non-text Content, 1.3.1 Info and Relationships, 1.4.1 Use of Color (not color alone), 2.1.1 Keyboard, 2.1.2 No Keyboard Trap, 2.4.1 Bypass Blocks, 2.4.2 Page Titled, 3.1.1 Language of Page, 4.1.2 Name Role Value.

Level AA: The Legal Standard

WCAG 2.2 contains 20 Level AA success criteria, bringing the total to 50 when combined with Level A. Level AA is the conformance target required by virtually all accessibility laws globally:

  • EU: EU Web Accessibility Directive (2016/2102) — WCAG 2.1 AA required for public sector websites.
  • EU: European Accessibility Act (EAA, effective June 2025) — WCAG 2.1 AA for private sector products and services.
  • US: Section 508 of the Rehabilitation Act — WCAG 2.0 AA for federal agencies and their contractors.
  • US: ADA — courts have increasingly interpreted WCAG 2.1 AA as the standard.
  • UK: Equality Act 2010 — WCAG 2.1 AA interpreted as the standard.
  • Canada: AODA (Ontario) — WCAG 2.0 AA required.
  • Australia: DDA — WCAG 2.0 AA as the baseline.

Key Level AA criteria not in Level A include: 1.4.3 Contrast Minimum, 1.4.4 Resize Text, 1.4.5 Images of Text, 1.4.10 Reflow, 1.4.11 Non-text Contrast, 1.4.12 Text Spacing, 2.4.6 Headings and Labels, 2.4.7 Focus Visible, 3.1.2 Language of Parts, 3.3.3 Error Suggestion, 3.3.4 Error Prevention.

Level AAA: Enhanced Accessibility

WCAG 2.2 contains 28 Level AAA criteria. The W3C explicitly states that not all Level AAA criteria can be satisfied for all content. Level AAA is not required by law for general web content but is appropriate for:

  • Sites serving users with severe cognitive disabilities — 3.1.3 Unusual Words, 3.1.4 Abbreviations, 3.1.5 Reading Level.
  • Sites heavily used by deaf-blind users — 1.2.9 Audio-only (Live), 1.4.9 Images of Text (No Exception).
  • Critical accessibility-focused applications — 2.1.3 Keyboard (No Exception), 2.2.3 No Timing.

As a best practice, aim for Level AAA on criteria that are achievable for your content without undue burden. For example, providing sign language interpretation (1.2.6) may not be feasible, but meeting 2.4.8 Location or 3.1.5 Reading Level often is.

Planning Your Conformance Target

Most organizations should target WCAG 2.2 AA as their conformance goal. The practical planning steps are:

  1. Start with a baseline audit — run automated tools and a manual review to understand your current conformance state.
  2. Triage by severity — fix all Level A failures first (they are the most severe). Then fix Level AA failures.
  3. Prioritize high-traffic pages and critical user journeys — the checkout flow, login, account management, and core content pages first.
  4. Set a realistic timeline — a mid-size site typically requires 3–6 months to achieve AA conformance from a poor baseline.
  5. Publish an accessibility statement — declare your conformance target, current known issues, and a contact for users who encounter barriers.
  6. Maintain conformance — accessibility is not a one-time project. Add accessibility to your definition of done for all new features.

WCAG Version Strategy: 2.1 vs 2.2

WCAG 2.2 is backward compatible with WCAG 2.1 — all 2.1 AA criteria are included in 2.2 AA, with one exception: 4.1.1 Parsing was removed. If you currently meet WCAG 2.1 AA, you need to address the 9 new 2.2 criteria to reach 2.2 AA conformance. The most impactful new 2.2 criteria are: 2.4.11 Focus Appearance, 2.4.12 Focus Not Obscured, 2.5.7 Dragging Movements, 2.5.8 Target Size (Minimum), and 3.2.6 Consistent Help.

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