What is the Difference Between WCAG A, AA, and AAA?

When you start researching web accessibility, you quickly encounter WCAG "levels" and wonder which one applies to you. Level A, AA, AAA—what do they actually mean, and which one do you need to meet?

I've had countless conversations with businesses confused about these levels. They hear "WCAG 2.2 AA compliance" but don't understand why AA specifically, or what they'd be missing if they only met Level A. Let's clear this up.

Q: What's the difference between WCAG Level A, AA, and AAA?

A: WCAG levels represent increasing degrees of accessibility. Level A is the minimum baseline (essential requirements), Level AA is the standard for legal compliance and most organizations, and Level AAA is the highest level with the most stringent requirements. Most laws and policies require Level AA conformance, which addresses the majority of accessibility barriers while remaining achievable for most websites.

Understanding WCAG Structure

How WCAG Is Organized

The Web Content Accessibility Guidelines (WCAG) are organized into four principles (Perceivable, Operable, Understandable, Robust), guidelines under each principle, and success criteria under each guideline. Each success criterion is assigned a level: A, AA, or AAA.

WCAG 2.2 contains 87 success criteria total:

• 32 at Level A
• 24 at Level AA
• 31 at Level AAA

To conform at a level, you must meet all criteria at that level AND all levels below it. So AA conformance means meeting all A criteria plus all AA criteria (56 total).

Why Three Levels?

The W3C created levels to balance accessibility with practicality. Some requirements are essential (A), some significantly improve accessibility (AA), and some provide enhanced access for specific disabilities but may be difficult for all sites to achieve (AAA).

This tiered approach lets organizations prioritize and show progress. Meeting Level A is better than nothing, but AA should be the goal.

Level A: Minimum Baseline

What Level A Covers

Level A success criteria address the most fundamental accessibility requirements. Without these, some users simply cannot use your site at all.

Key Level A requirements include:

Non-text Content (1.1.1): All images must have text alternatives (alt text).

Audio and Video (1.2.1-1.2.3): Pre-recorded audio-only content needs transcripts; pre-recorded video needs captions or audio description.

Info and Relationships (1.3.1): Information conveyed visually must also be programmatically determinable. A heading must be coded as a heading, not just styled to look like one.

Meaningful Sequence (1.3.2): Content order in code must make logical sense when CSS is disabled.

Keyboard (2.1.1): All functionality must be operable via keyboard.

No Keyboard Trap (2.1.2): If keyboard focus enters a component, users must be able to move focus away using only keyboard.

Pause, Stop, Hide (2.2.2): Moving, blinking, or auto-updating content must be controllable.

Three Flashes (2.3.1): Content must not flash more than three times per second.

Page Titled (2.4.2): Pages must have descriptive titles.

Focus Order (2.4.3): Tab order must be logical and preserve meaning.

Link Purpose (2.4.4): Link text must be determinable from the link itself or its context.

Language of Page (3.1.1): Default language must be programmatically set.

On Focus/Input (3.2.1-3.2.2): Receiving focus or changing a setting shouldn't cause unexpected context changes.

Error Identification (3.3.1): Input errors must be identified and described in text.

Labels or Instructions (3.3.2): Inputs must have labels or instructions.

Parsing (4.1.1): HTML must be properly nested without duplicate IDs.

Name, Role, Value (4.1.2): Custom components must expose name, role, and value to assistive technology.

What Level A Misses

Level A doesn't require:

• Specific color contrast ratios
• Captions for live video
• Multiple navigation methods
• Visible focus indicators
• Consistent navigation and identification
• Error suggestions or prevention

Meeting only Level A leaves significant accessibility gaps.

Level AA: The Standard

Why AA Is the Target

Level AA is the standard because it:

• Addresses the most significant barriers
• Is achievable for virtually all websites
• Is referenced by most accessibility laws (ADA, Section 508, EAA)
• Covers needs of the broadest range of disabilities

When someone says a site needs to be "WCAG compliant," they almost always mean Level AA.

What Level AA Adds

Building on Level A, Level AA includes:

Captions (Live) (1.2.4): Live video content needs real-time captions.

Audio Description (1.2.5): Pre-recorded video needs audio description of visual content.

Contrast Minimum (1.4.3): Text must have 4.5:1 contrast ratio (3:1 for large text).

Resize Text (1.4.4): Text must be resizable to 200% without loss of content.

Images of Text (1.4.5): Text should be real text, not images of text.

Reflow (1.4.10): Content must reflow at 400% zoom without horizontal scrolling.

Non-text Contrast (1.4.11): UI components and graphics need 3:1 contrast.

Text Spacing (1.4.12): Content must remain functional with increased text spacing.

Content on Hover or Focus (1.4.13): Additional content appearing on hover/focus must be dismissible and persistent.

Multiple Ways (2.4.5): Multiple ways to locate pages within a site (navigation, search, sitemap).

Headings and Labels (2.4.6): Headings and labels must be descriptive.

Focus Visible (2.4.7): Keyboard focus must be visible.

Focus Not Obscured (Minimum) (2.4.11): Focused item must not be entirely hidden by other content.

Consistent Navigation (3.2.3): Navigation must be consistent across pages.

Consistent Identification (3.2.4): Same functionality must be identified consistently.

Error Suggestion (3.3.3): When errors are detected and suggestions known, provide them.

Error Prevention (3.3.4): For legal/financial transactions, submissions must be reversible, checkable, or confirmable.

Status Messages (4.1.3): Status messages must be announced to screen readers without focus change.

Level AA Impact

These requirements significantly improve usability. Color contrast affects everyone, not just those with vision impairments. Visible focus indicators help any keyboard user. Error suggestions reduce frustration for all users.

AA is the sweet spot—comprehensive enough to be meaningful, achievable enough to be practical.

Level AAA: Enhanced Access

What Level AAA Includes

Level AAA provides the highest degree of accessibility, adding requirements like:

Sign Language (1.2.6): Provide sign language interpretation for pre-recorded audio.

Extended Audio Description (1.2.7): Pause video to provide more detailed audio description.

Media Alternative (1.2.8): Provide full text alternative for pre-recorded video.

Enhanced Contrast (1.4.6): 7:1 contrast ratio for text.

Low or No Background Audio (1.4.7): Limit background sounds in audio content.

Visual Presentation (1.4.8): Provide extensive text customization options.

Keyboard (No Exception) (2.1.3): All functionality must work with keyboard, no exceptions.

No Timing (2.2.3): No time limits unless real-time or essential.

Interruptions (2.2.4): Interruptions can be postponed or suppressed.

Re-authenticating (2.2.5): Data is preserved after session expiration.

Three Flashes (2.3.2): No flashing content at all.

Location (2.4.8): Provide breadcrumbs or other location information.

Link Purpose (Link Only) (2.4.9): Link text alone must identify destination.

Section Headings (2.4.10): Content is organized with section headings.

Unusual Words (3.1.3): Define jargon, idioms, and specialized terms.

Abbreviations (3.1.4): Provide expansions for abbreviations.

Reading Level (3.1.5): Provide simplified versions of complex content.

Pronunciation (3.1.6): Provide pronunciation guidance where needed.

Change on Request (3.2.5): Context changes only on user request.

Help (3.3.5): Context-sensitive help is available.

Error Prevention (All) (3.3.6): Error prevention for all submissions, not just legal/financial.

Why AAA Isn't Typically Required

The W3C itself notes: "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."

Some AAA criteria are impractical for certain content. Providing sign language interpretation for all audio is expensive and may not be feasible. Ensuring all content is at a lower secondary education reading level isn't possible for technical documentation.

When to Pursue AAA

Consider AAA for:

• Specific user groups (sites primarily serving deaf users might prioritize sign language)
• Critical content (emergency information benefits from lower reading levels)
• Competitive advantage (exceeding standards shows commitment)
• Individual criteria that fit your audience

Many organizations meet some AAA criteria naturally without aiming for full conformance.

Which Level Do You Need?

Legal Requirements

Different regulations specify levels:

ADA (Americans with Disabilities Act): Courts typically look to WCAG 2.0/2.1 AA as the standard, though ADA doesn't explicitly reference WCAG.

Section 508: Requires WCAG 2.0 Level AA for federal agencies and contractors.

European Accessibility Act (EAA): References EN 301 549, which aligns with WCAG 2.1 AA.

AODA (Ontario): Requires WCAG 2.0 AA.

The consistent theme: Level AA is the legal standard. See the W3C's accessibility laws listing for comprehensive information.

Practical Recommendations

Aim for Level AA. It's the standard expected by laws, referenced in lawsuits, and achievable for any website with proper development practices.

Don't stop at Level A. Meeting only Level A leaves significant gaps—no contrast requirements, no visible focus, no error suggestions. Users will still face barriers.

Consider select AAA criteria. Some AAA requirements are easy to meet and provide value. 7:1 contrast isn't difficult if you plan for it. Section headings benefit all users.

How to Approach Compliance

1. Test against Level AA using automated testing tools as a starting point
2. Prioritize Level A failures first—they're often the most severe barriers
3. Address Level AA gaps to achieve standard compliance
4. Evaluate AAA criteria for criteria that fit your content and audience

Testing for Each Level

What Automated Tools Check

Automated testing tools typically test against Level AA by default. They can identify many A and AA failures:

• Missing alt text (A)
• Color contrast issues (AA)
• Missing form labels (A)
• Invalid ARIA (A)
• Missing document language (A)

What Requires Manual Testing

Some criteria, especially at AA and AAA, require human judgment:

• Whether alt text is appropriate (A)
• Whether headings are descriptive (AA)
• Whether content makes sense without color (A)
• Whether focus order is logical (A)
• Screen reader testing for actual user experience

Documenting Conformance

When claiming conformance, specify:

• WCAG version (2.0, 2.1, 2.2)
• Level (A, AA, AAA)
• Scope (entire site, specific features)
• Any exceptions

For example: "This website conforms to WCAG 2.2 Level AA" or "The checkout process conforms to WCAG 2.1 Level AA."

FAQ Section

Q: Can I claim partial conformance?

A: WCAG conformance is binary—you either meet all criteria at a level or you don't. However, you can document partial conformance by listing which criteria are met and which have known issues. Many accessibility statements acknowledge areas still being addressed.

Q: Is Level AAA ever required?

A: Rarely as a blanket requirement. Some organizations choose AAA for specific content. Government emergency communications might target AAA for maximum reach. But requiring AAA for entire sites is uncommon because some criteria can't be met for certain content types.

Q: Does meeting AA mean I meet A?

A: Yes. AA conformance requires meeting all A criteria plus all AA criteria. AAA requires all three levels. You can't skip lower levels.

Q: How often do requirements change?

A: The W3C releases new WCAG versions periodically. WCAG 2.0 came in 2008, 2.1 in 2018, 2.2 in 2023. New versions add criteria but don't remove existing ones. WCAG 2.2 added nine new success criteria, mostly at Level A and AA.

Q: Should I aim higher than what's legally required?

A: Meeting AA is the baseline. Going beyond helps more users and demonstrates genuine commitment. Selectively implementing AAA criteria that fit your content and audience is smart practice, even if full AAA isn't the goal.

Making Level Choices

The WCAG levels aren't arbitrary—they represent careful consideration of impact and feasibility. Level A is the floor no site should drop below. Level AA is the standard everyone should meet. Level AAA is an aspirational target for enhanced accessibility.

For most organizations, the answer is clear: target WCAG 2.2 Level AA. It's what laws expect, what users need, and what's achievable with thoughtful design and development.

Want to know where your site stands? Get a free accessibility scan to identify which WCAG criteria you're meeting and where gaps exist.

Related Articles:

• WCAG 2.2: What's New and How to Comply
• How Do I Test My Website for Accessibility for Free?
• Website Accessibility Testing Checklist

Quick note: we used AI to help write this article, and our team reviewed it for accuracy. We're passionate about making the web accessible, but accessibility law can get complicated. If you're making decisions about compliance, definitely loop in a professional who knows your specific situation.