International standard

WCAG compliance guide

The Web Content Accessibility Guidelines (WCAG) are the global benchmark for web accessibility. Understand what WCAG 2.1 and 2.2 require, which conformance level applies to your site, and how to meet the standard.

Check WCAG compliance
WCAG 2.2
Current standard
Level AA
Legal requirement worldwide
78 criteria
Success criteria in WCAG 2.2
POUR
Four core principles

What are WCAG guidelines?

Web Content Accessibility Guidelines (WCAG) are the internationally recognized standards for making web content accessible to people with disabilities. Published by the World Wide Web Consortium (W3C), WCAG provides technical specifications that developers and designers follow to build websites that work for everyone, including people with visual, auditory, motor, or cognitive impairments.

WCAG is not a law in itself, but it is referenced by accessibility legislation worldwide. The European Accessibility Act, ADA Title III, Section 508, and many other regulations point to WCAG as the technical standard for web accessibility compliance.

WCAG versions explained

  • WCAG 2.0 (2008): The first widely adopted version. Established the foundational framework for web accessibility.
  • WCAG 2.1 (2018): Added 17 new success criteria covering mobile accessibility and cognitive disabilities.
  • WCAG 2.2 (2023): The current version. Added 9 further criteria focused on mobile usability, cognitive accessibility, and authentication.
  • WCAG 3.0: In active development. Expected to differ significantly from the 2.x series. Not yet referenced by any legal standard.

Why WCAG matters

  • Global standard: Recognized in over 40 countries as the benchmark for web accessibility.
  • Legal requirement: Referenced by the EAA, ADA, Section 508, and accessibility laws worldwide.
  • Court-accepted: Used as evidence in accessibility lawsuits and legal proceedings.
  • Business benefit: Following WCAG improves usability for all users and strengthens SEO.
  • Future-proof: Regular updates ensure the standard stays relevant as technology evolves.

WCAG conformance levels: A, AA, and AAA

WCAG defines three levels of conformance, each building on the previous. Understanding these levels is essential for knowing what your site actually needs to achieve.

A

Level A – minimum

The most basic accessibility requirements. Meeting only Level A leaves significant barriers in place for users with disabilities.

Examples:

  • All images must have alt text
  • Videos must have captions or audio descriptions
  • All functionality must be keyboard accessible
  • Page titles must describe the content
  • Color cannot be the only way to convey information

WHO SHOULD AIM FOR THIS: Level A alone is insufficient for legal compliance. It is a starting point, not a destination.

AA

Level AA — standard

The industry standard and the level required by most accessibility laws. Addresses the major barriers that prevent people with disabilities from using the web.

Examples (includes all Level A plus these):

  • Text must have a minimum color contrast ratio of 4.5:1
  • Text must be resizable up to 200% without loss of functionality
  • Captions must be provided for all live audio content
  • Multiple ways to navigate and find pages must be available
  • Form inputs must have clear labels and instructions
  • Headings and labels must describe topic or purpose

WHO SHOULD AIM FOR THIS: Every website should target Level AA. It is the legal requirement under the EAA, ADA, and most other regulations.

AAA

Level AAA — enhanced

The highest level of accessibility. Not required by law and not achievable for all content types, but represents best-in-class practice.

Examples (includes all Level A and AA plus these):

  • Enhanced color contrast ratio of 7:1
  • Sign language interpretation for prerecorded audio
  • Extended audio descriptions for video
  • Reading level no higher than lower secondary education
  • Context-sensitive help available throughout

WHO SHOULD AIM FOR THIS: Government sites, educational institutions, and organizations serving vulnerable populations. Not typically required.

Which level should you target?

For legal compliance and best practice, WCAG 2.2 Level AA is the target to aim for:

  • European Accessibility Act: Requires WCAG 2.1 Level AA (via EN 301 549), with WCAG 2.2 expected in future updates
  • ADA compliance: Courts accept WCAG 2.1 Level AA as the standard
  • Section 508: Aligned with WCAG 2.0 Level AA, moving toward 2.1
  • Most international laws: Reference WCAG 2.1 Level AA as the minimum

Building to WCAG 2.2 AA satisfies all of the above and positions your site ahead of forthcoming regulatory updates.

The four principles of WCAG (POUR)

All WCAG guidelines are organized around four fundamental principles, known by the acronym POUR. Every success criterion falls under one of these principles.

1. Perceivable

Information and user interface components must be presentable to users in ways they can perceive.

Key requirements:

  • Text alternatives: Provide alt text for images and non-text content
  • Time-based media: Captions and transcripts for audio and video
  • Adaptable: Content can be presented in different ways without losing information
  • Distinguishable: Sufficient color contrast and flexible text sizing

2. Operable

User interface components and navigation must be operable by all users.

Key requirements:

  • Keyboard accessible: All functionality available via keyboard
  • Enough time: Users have adequate time to read and interact with content
  • Seizures: No content that flashes more than 3 times per second
  • Navigable: Clear navigation and multiple ways to find content
  • Input modalities: Functions available through various input methods

3. Understandable

Information and the operation of the interface must be understandable.

Key requirements:

  • Readable: Text content is readable and understandable
  • Predictable: Pages appear and operate in predictable ways
  • Input assistance: Users are helped to avoid and correct mistakes
  • Language: Page language is identified programmatically

4. Robust

Content must be robust enough to work with current and future technologies.

Key requirements:

  • Compatible: Maximize compatibility with assistive technologies
  • Valid code: HTML and ARIA used correctly
  • Name, role, value: UI components are properly identified
  • Status messages: Important updates are communicated to users

WCAG 2.1 vs WCAG 2.2: what changed?

WCAG 2.2, published in October 2023, builds on WCAG 2.1 by adding 9 new success criteria and removing one outdated requirement. Conforming to WCAG 2.2 means automatically conforming to WCAG 2.1 as well, since every 2.1 criterion carries over.

New success criteria in WCAG 2.2

The additions focus primarily on mobile usability, cognitive accessibility, and authentication. Here is what changed:

Level A additions:

  • 3.2.6 Consistent help: Help mechanisms (contact info, chat, FAQs) must appear in the same location across pages
  • 3.3.7 Redundant entry: Information already entered in a session must be auto-populated or available to select rather than re-typed

Level AA additions:

  • 2.4.11 Focus not obscured (minimum): Focused elements must not be entirely hidden by sticky headers, banners, or overlays
  • 2.5.7 Dragging movements: Any drag-and-drop interaction must have an alternative single-pointer method
  • 2.5.8 Target size (minimum): Interactive elements must be at least 24×24 CSS pixels
  • 3.3.8 Accessible authentication (minimum): Authentication cannot rely solely on cognitive tests without an alternative

Level AAA additions:

  • 2.4.12 Focus not obscured (Enhanced): Focused elements must be fully visible, not just partially
  • 2.4.13 Focus appearance: Focus indicators must meet minimum size and contrast requirements
  • 3.3.9 Accessible authentication (enhanced): No cognitive function tests permitted at all during authentication

Removed:

  • 4.1.1 Parsing: HTML validity requirement removed as modern browsers and assistive technologies handle minor markup errors reliably

Should you target WCAG 2.1 or 2.2?

The short answer is WCAG 2.2. It is backward compatible with 2.1, so meeting it satisfies both versions simultaneously. The new AA-level criteria address real barriers that affect real users, and the regulatory landscape is already moving in that direction.

  • For legal compliance: WCAG 2.1 Level AA currently satisfies the EAA, ADA, and most regulations
  • For best practice: WCAG 2.2 Level AA future-proofs your site against forthcoming regulatory updates
  • The practical approach: Build to 2.2, cover both standards at once

Scanluma scans for both WCAG 2.1 and 2.2, so you can see exactly where your site stands against the current standard and where gaps exist.

Most common WCAG violations

These are the accessibility issues found most frequently on websites, based on aggregated scanning data across all WCAG levels.

Top 10 WCAG violations

1. Missing alt text (1.1.1 — level A)

Images lack alternative text, making content invisible to screen readers. Found on roughly 60% of websites scanned.

2. Low color contrast (1.4.3 — level AA)

Text does not have sufficient contrast against its background. Affects readability for users with low vision or color blindness. One of the most widespread failures, appearing on around 86% of websites.

3. Empty links (2.4.4 — level A)

Links with no text, or containing only an image without alt text. Screen readers cannot describe the link purpose to users.

4. Missing form labels (3.3.2 — level A)

Form inputs without associated labels make it impossible for screen readers to identify the purpose of each field.

5. Missing document language (3.1.1 — level A)

Page language not specified in HTML, preventing screen readers from applying correct pronunciation rules.

6. Broken heading structure (1.3.1 — level A)

Headings that skip levels or are chosen for visual size rather than document structure. Breaks navigation for assistive technology users.

7. Missing or incorrect ARIA (4.1.2 — level A)

ARIA attributes that are absent, used incorrectly, or conflict with native HTML semantics. Causes unpredictable behavior in assistive technologies.

8. Non-descriptive link text (2.4.4 — level A)

Links using generic text like “click here” or “read more” without surrounding context. Screen reader users navigating by link list cannot determine where links lead.

9. Missing focus indicators (2.4.7 — level AA)

No visible indication when elements receive keyboard focus. Users navigating without a mouse cannot track their position on the page.

10. Videos without captions (1.2.2 — level A)

Prerecorded videos without captions or transcripts. Deaf and hard-of-hearing users cannot access the audio content.

How Scanluma ensures WCAG compliance

Scanluma automates WCAG 2.1 and 2.2 testing, checking your website against all Level A and AA success criteria in a single scan.

1

Complete coverage

Scanluma checks your site against every WCAG 2.1 and 2.2 level A and AA success criterion. Comprehensive scanning identifies violations across your entire site, not just a sample of pages.

2

Detailed reports

Each issue includes the specific WCAG success criterion violated, why it matters for users, and the HTML code snippet needed to fix it. No guesswork about what to change or where.

3

Continuous monitoring

Automated scans keep your site compliant as content and code evolve. New violations are flagged before they reach users or trigger legal exposure.

What Scanluma tests for

Scanluma automatically checks for 50+ types of WCAG violations across all four POUR principles:

Perceivable issues

  • Missing alt text on images
  • Insufficient color contrast
  • Missing video captions
  • Unclear link text
  • Complex data tables without headers

Operable issues

  • Missing keyboard accessibility
  • Keyboard traps
  • Missing skip navigation links
  • Unclear or absent focus indicators
  • Non-descriptive page titles

Understandable issues

  • Missing form labels
  • Unclear error messages
  • Missing language attributes
  • Inconsistent navigation patterns
  • Ambiguous instructions

Robust issues

  • Incorrect ARIA usage
  • Missing name, role, and value attributes
  • Duplicate IDs
  • Missing status messages
  • Invalid HTML markup

Achieving WCAG compliance in 4 weeks

Most websites can reach WCAG 2.1 Level AA compliance within four weeks using a structured, prioritized approach.

Week 1: assessment

Run your first scan with Scanluma to identify all WCAG violations across your site. Review the report to understand the full scope of work, the number of issues, their severity, and which pages are most affected.

Week 2: critical Issues

Address Level A violations first. Focus on the barriers that block access entirely: missing alt text, unlabeled form fields, and keyboard accessibility failures.

Week 3: level AA Requirements

Work through the Level AA criteria. This includes color contrast, text resizing, enhanced navigation features, and the new WCAG 2.2 additions such as touch target sizing and focus visibility.

Week 4: testing and Documentation

Run final scans to verify all issues are resolved. Export your compliance report for documentation purposes and publish an accessibility statement on your website.

WCAG compliance FAQs

What’s the difference between WCAG 2.0, 2.1, and 2.2?

WCAG 2.1 (2018) builds on 2.0 by adding 17 new success criteria covering mobile and cognitive accessibility. WCAG 2.2 (2023) adds 9 more criteria, primarily around mobile usability, focus visibility, and authentication. Each version is backward compatible, so meeting WCAG 2.2 means automatically meeting 2.1 and 2.0. WCAG 2.2 is the current version and the recommended target for any new compliance work.

Do I need to meet Level AAA?

No. Level AAA is not required by law and is not achievable for all content types. WCAG 2.1 Level AA is the standard required by the European Accessibility Act, ADA, and most global regulations. Some organizations voluntarily pursue Level AAA improvements, but there is no legal obligation to do so.

Can automated tools check all WCAG criteria?

Automated tools like Scanluma detect a significant portion of WCAG violations quickly and consistently. Some criteria require human judgment, such as whether alt text is meaningful or whether content is written at an appropriate reading level. Automated scanning identifies the majority of technical failures and provides a reliable foundation for compliance work.

How often should I test for WCAG compliance?

Test initially to establish a baseline, then schedule scans whenever significant content or design changes are made. With Scanluma’s Pro plan, automated scans can be configured to run regularly, catching new issues before they accumulate and keeping your compliance status visible over time.

Is WCAG 2.1 Level AA the same as Section 508?

Section 508 was updated in 2017 to align with WCAG 2.0 Level AA. While not identical, meeting WCAG 2.1 Level AA generally satisfies Section 508 requirements for web content. Section 508 also includes requirements for software and hardware that go beyond websites.

What happens if I only meet some WCAG criteria?

Partial compliance is not recognized as formal conformance. To claim WCAG 2.1 Level AA compliance, all Level A and AA criteria must be met. That said, fixing the most critical issues is always better than fixing nothing. Prioritize barriers that affect the most users, such as missing alt text, low color contrast, and keyboard accessibility failures.

Do WCAG requirements apply to PDFs and documents?

Yes. PDFs and downloadable documents available on your website must also meet accessibility standards, including proper structure, alt text for images, and screen reader compatibility. Scanluma focuses on web content. Separate tools are needed to audit PDF accessibility.

How long does WCAG compliance take?

Most websites can reach WCAG 2.1 Level AA compliance in 3 to 4 weeks using Scanluma’s guided reports and code snippets. The timeline depends on the number of issues found and available development resources. Simpler sites may take 1 to 2 weeks. Complex web applications may take 6 to 8 weeks.

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