Understanding WCAG 2.1: A Complete Accessibility Guide

WCAG 2.1 was published in June 2018 and added 17 new success criteria to WCAG 2.0. And even though WCAG 2.2 is now the latest version of these standards, many regulations, procurement requirements, and accessibility policies still specifically point to WCAG 2.1. 

This includes the European Accessibility Act’s EN 301 549 baseline, the EU Web Accessibility Directive, and countless existing supplier agreements and contracts that have not yet transitioned to newer standards.

For businesses, developers, and website owners, understanding WCAG 2.1 is still essential for achieving and maintaining digital accessibility compliance. 

In this guide, we’ll explain what WCAG 2.1 is, what AA-level compliance means in practice, the 17 new success criteria introduced after WCAG 2.0, and how WCAG 2.1 compares to WCAG 2.2.

What Is WCAG 2.1?

TL;DR: WCAG 2.1 is the internationally recognized web accessibility standard published by the W3C in 2018. It expands on WCAG 2.0 with 17 new accessibility requirements while remaining compatible with both older and newer versions of the guidelines.

WCAG 2.1 is a set of internationally recognized web accessibility guidelines published by the World Wide Web Consortium as an official recommendation on June 5, 2018. 

The guidelines were created to help websites, applications, and digital content become more accessible to people with disabilities, including users with visual, auditory, motor, and cognitive impairments.

WCAG 2.1 builds directly on WCAG 2.0, which means all previous success criteria still apply. 

The update introduced 17 additional success criteria, with a large focus on mobile accessibility, touch interactions, low vision support, and cognitive accessibility. 

It should be noted that WCAG 2.1 is backward-compatible with WCAG 2.0 and also forms a subset of WCAG 2.2, making it a strong foundation for organizations working toward long-term accessibility compliance.

WCAG 2.1 Conformance Levels (A, AA, AAA)

WCAG 2.1 is organized into three levels of conformance: A, AA, and AAA. Each level builds on the previous one and increases the accessibility requirements websites and digital platforms must meet.

Level A: The Minimum Accessibility Standard

Level A is the most basic level of accessibility compliance. It focuses on removing the biggest barriers that could prevent users with disabilities from accessing content or navigating a website at all.

Examples of Level A requirements include:

• Providing text alternatives for images
• Ensuring websites can be navigated using a keyboard
• Avoiding content that may trigger seizures
• Using clear page structures and labels

WCAG 2.1 contains 30 Level A success criteria.

While Level A is an important starting point, it is generally not considered sufficient for full accessibility compliance or legal risk reduction on its own.

Level AA: The Industry and Legal Standard

Level AA is the most widely adopted and legally recognized conformance level. It expands on Level A by improving usability and accessibility for a broader range of users, particularly those with visual, cognitive, and mobility impairments.

Additional AA requirements include:

• Minimum color contrast ratios
• Resizable text
• Consistent navigation and identification
• Better support for users with low vision and mobile devices

WCAG 2.1 adds 20 additional Level AA success criteria, bringing the combined total for Levels A and AA to 50 success criteria.

In practice, WCAG 2.1 AA is the level most organizations target because it is the benchmark referenced by many accessibility laws, standards, and procurement requirements worldwide. 

Level AAA: The Highest Accessibility Standard

Level AAA is the most advanced level of accessibility conformance. It includes additional requirements designed to provide the broadest possible accessibility support.

Examples may include:

• Enhanced color contrast requirements
• Sign language interpretation for prerecorded audio
• More extensive error prevention and assistance features

WCAG 2.1 includes 28 additional AAA success criteria, bringing the total number of success criteria across all levels to 78.

Although AAA compliance demonstrates a very high commitment to accessibility, it is not usually required by law and is often difficult to achieve across every page or feature of a website. 

WCAG 2.1 Level AA Success Criteria

Now that you have a better understanding of the different WCAG 2.1 levels, let’s delve into the success criteria that are specific to Level AA. 

Bear in mind that WCAG 2.1 Level AA includes the Level A requirements plus additional Level AA criteria, bringing the total to 50 success criteria. 

Perceivable

Content must be presented in ways users can perceive, regardless of their abilities or assistive technologies.

1.1 Text Alternatives

• 1.1.1 Non-text Content (A). Provide text alternatives for images, icons, charts, and other non-text elements, so screen readers can interpret them.

1.2 Time-Based Media

• 1.2.1 Audio-only and Video-only (Prerecorded) (A). Provide alternatives for prerecorded audio-only or video-only content.
• 1.2.2 Captions (Prerecorded) (A). Add captions to prerecorded videos with audio.
• 1.2.3 Audio Description or Media Alternative (Prerecorded) (A). Provide audio descriptions or text alternatives for prerecorded video content.
• 1.2.4 Captions (Live) (AA). Provide captions for live video broadcasts.
• 1.2.5 Audio Description (Prerecorded) (AA). Add audio descriptions to prerecorded videos where visual information is important.

1.3 Adaptable

• 1.3.1 Info and Relationships (A). Use proper headings, labels, and semantic HTML, so the structure is understandable to assistive technologies.
• 1.3.2 Meaningful Sequence (A). Ensure content order remains logical when read by assistive technologies.
• 1.3.3 Sensory Characteristics (A). Do not rely only on shape, color, size, or location when giving instructions.
• 1.3.4 Orientation (AA). Content should work in both portrait and landscape orientation unless a specific orientation is essential.
• 1.3.5 Identify Input Purpose (AA). Input fields should clearly communicate their purpose programmatically, such as name or email fields.

1.4 Distinguishable

• 1.4.1 Use of Color (A). Do not use color alone to convey meaning.
• 1.4.2 Audio Control (A). Users must be able to pause or stop audio that plays automatically.
• 1.4.3 Contrast (Minimum) (AA). Text and background colors must meet minimum contrast ratios for readability.
• 1.4.4 Resize Text (AA). Text should remain readable and functional when enlarged up to 200%.
• 1.4.5 Images of Text (AA). Use real text instead of text embedded inside images wherever possible.
• 1.4.10 Reflow (AA). Content should adapt without requiring horizontal scrolling on smaller screens.
• 1.4.11 Non-text Contrast (AA). Interactive elements and graphical objects must have sufficient contrast.
• 1.4.12 Text Spacing (AA). Content should remain usable when users adjust spacing between letters, words, and lines.
• 1.4.13 Content on Hover or Focus (AA). Tooltips and popups triggered by hover or focus should be dismissible and accessible.

Operable

Users must be able to navigate and interact with the interface successfully.

2.1 Keyboard Accessible

• 2.1.1 Keyboard (A). All functionality should be accessible using only a keyboard.
• 2.1.2 No Keyboard Trap (A). Users must be able to move focus away from any component using a keyboard.
• 2.1.4 Character Key Shortcuts (A). Single-character keyboard shortcuts should be adjustable or removable.

2.2 Enough Time

• 2.2.1 Timing Adjustable (A). Users should have enough time to read and complete tasks.
• 2.2.2 Pause, Stop, Hide (A). Moving or auto-updating content must be pausable or stoppable.

2.3 Seizures and Physical Reactions

• 2.3.1 Three Flashes or Below Threshold (A). Content must avoid flashing that could trigger seizures.

2.4 Navigable

• 2.4.1 Bypass Blocks (A). Provide skip links or other methods to bypass repetitive content.
• 2.4.2 Page Titled (A). Each page should have a descriptive title.
• 2.4.3 Focus Order (A). Keyboard focus should move in a logical order.
• 2.4.4 Link Purpose (In Context) (A). Links should make sense from their surrounding context.
• 2.4.5 Multiple Ways (AA). Users should have multiple methods for finding pages, such as menus or search.
• 2.4.6 Headings and Labels (AA). Headings and labels should clearly describe content or functionality.
• 2.4.7 Focus Visible (AA). Keyboard focus indicators must remain visible.

2.5 Input Modalities

• 2.5.1 Pointer Gestures (A). Complex gestures should have simpler alternatives.
• 2.5.2 Pointer Cancellation (A). Users should be able to cancel pointer actions before completion.
• 2.5.3 Label in Name (A). Visible labels should match accessible names used by assistive technologies.
• 2.5.4 Motion Actuation (A). Functions triggered by motion should also work through standard controls.

Understandable

Content and interfaces should be easy to understand and predict.

3.1 Readable

• 3.1.1 Language of Page (A). Specify the main language of the page in the code.

3.2 Predictable

• 3.2.1 On Focus (A). Elements should not unexpectedly change when focused.
• 3.2.2 On Input (A). User input should not automatically trigger major changes without warning.
• 3.2.3 Consistent Navigation (AA). Navigation components should appear consistently across pages.
• 3.2.4 Consistent Identification (AA). Components with the same function should be identified consistently.

3.3 Input Assistance

• 3.3.1 Error Identification (A). Clearly identify form errors.
• 3.3.2 Labels or Instructions (A). Provide labels and instructions where user input is required.
• 3.3.3 Error Suggestion (AA). Offer suggestions for correcting errors when possible.
• 3.3.4 Error Prevention (Legal, Financial, Data) (AA). Provide safeguards for important submissions, such as confirmations or reversals.

Robust

Content should remain compatible with current and future technologies, including assistive tools.

4.1 Compatible

• 4.1.1 Parsing (A). Code should avoid major HTML errors that break assistive technology compatibility.
• 4.1.2 Name, Role, Value (A). Interface elements should expose proper names, roles, and values programmatically.
• 4.1.3 Status Messages (AA). Status updates should be communicated to assistive technologies without requiring focus changes.

What’s New in WCAG 2.1 (vs 2.0)? 

WCAG 2.1 introduced 17 new success criteria on top of WCAG 2.0. 

While WCAG 2.0 focused heavily on desktop accessibility, WCAG 2.1 expanded accessibility guidance for mobile devices, touch interactions, low-vision users, and people with cognitive disabilities.

The 17 New WCAG 2.1 Success Criteria

The Most Referenced WCAG 2.1 Additions

Some WCAG 2.1 criteria are referenced far more frequently in audits, remediation projects, and accessibility lawsuits because they directly affect mobile usability and low-vision accessibility.

1.4.10 Reflow (AA)

One of the most important additions, Reflow requires websites to adapt properly at high zoom levels and on smaller screens without forcing users to scroll horizontally. This criterion significantly strengthened responsive accessibility expectations.

1.4.11 Non-text Contrast (AA)

This criterion extended contrast requirements beyond text to include buttons, icons, form controls, focus indicators, and other interface components.

1.4.12 Text Spacing (AA)

Users who modify line height, letter spacing, or paragraph spacing must still be able to read and use the content without layout breakage.

2.5.5 Target Size (AAA)

Although this is a Level AAA criterion, it became highly influential in mobile accessibility discussions because it encourages larger touch targets that are easier to tap accurately.

1.3.4 Orientation (AA)

Websites and applications should not force users into portrait-only or landscape-only modes unless absolutely necessary, improving accessibility for users with mounted devices or assistive setups.

WCAG 2.1 vs 2.2: When Each Applies

Although WCAG 2.2 is now the newest version of the guidelines, WCAG 2.1 remains extremely important because many laws, policies, and contracts still explicitly reference it.

Which Version Should You Target?

For most organizations, the practical answer is simple:

• WCAG 2.2 AA is the recommended target for new websites, redesigns, and long-term accessibility planning.
• WCAG 2.1 AA is still the minimum standard referenced by many existing legal and contractual requirements.

Importantly, WCAG 2.2 is backward-compatible with WCAG 2.1. This means that if your website complies with WCAG 2.2 AA, you have effectively also complied with WCAG 2.1 AA in almost all cases.

The main exception is 4.1.1 Parsing, which was removed in WCAG 2.2 because modern browsers and assistive technologies now handle minor parsing issues more consistently. 

Other than that removal, WCAG 2.2 builds directly on the WCAG 2.1 framework.

Is WCAG 2.1 Legally Required?

In many regions, WCAG 2.1 AA is either directly referenced in accessibility regulations or widely treated as the accepted compliance benchmark for digital accessibility.

• In the United States, lawsuits under the Americans with Disabilities Act (ADA) Title III commonly reference WCAG 2.0 AA or WCAG 2.1 AA as the standard for accessible websites and digital services. Courts are also increasingly recognising WCAG 2.2 as an acceptable modern benchmark.
• Section 508, which applies to U.S. federal agencies, still officially references WCAG 2.0 AA. However, this is widely viewed as a regulatory lag rather than a best-practice recommendation.
• In Europe, the European Accessibility Act (EAA) and EN 301 549 standard use WCAG 2.1 AA as their core accessibility baseline for digital products and services.
• In Canada, the Accessibility for Ontarians with Disabilities Act (AODA) currently requires WCAG 2.0 AA compliance, although many organizations are already moving toward WCAG 2.1 in preparation for future updates.

Because regulations evolve slowly, many organizations now target WCAG 2.2 AA proactively while still ensuring they meet all WCAG 2.1 AA requirements referenced in existing laws and contracts.

How to Test for WCAG 2.1 AA Compliance

Testing for WCAG 2.1 AA compliance typically involves a combination of automated accessibility tools and manual human evaluation. 

Automated scans are useful for identifying common issues such as missing alt text, color contrast failures, empty links, or heading structure problems. However, automated testing generally only detects around 40% of accessibility issues.

The remaining issues require manual testing to assess real usability and accessibility. This includes:

• Keyboard-only navigation
• Screen reader compatibility
• Focus visibility and logical tab order
• Form usability and error handling
• Responsive reflow and zoom behaviour
• Accessible interactive components and menus

Because many WCAG 2.1 AA criteria depend on context and user experience, manual testing remains essential for achieving meaningful compliance. 

Most accessibility audits and tools like AccessibilityChecker.org combine automated scanning, expert review, and assistive technology testing to provide accurate results.

Conclusion

WCAG 2.1 remains one of the most important web accessibility standards in use today. While WCAG 2.2 is becoming the preferred target for modern accessibility projects, WCAG 2.1 AA continues to serve as the compliance baseline referenced by many laws, regulations, and procurement requirements worldwide.

By understanding the WCAG 2.1 success criteria, organizations can create more inclusive digital experiences while reducing legal and compliance risks.