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WCAG A vs AA vs AAA: what each conformance level means

WCAG has three conformance levels: A is the minimum, AA adds criteria and is the level the laws we track name when they name one, and AAA is the highest. WCAG 2.2 has 31 criteria at A, 24 at AA and 31 at AAA. Conforming at a level means meeting every criterion at that level and below.

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WCAG sorts its success criteria into three conformance levels so that different laws, contracts and projects can ask for different amounts. This page explains what each level contains, what it takes to conform at a level, how W3C decided which criteria go where, which level the laws we track name, and what W3C says about aiming for AAA. The counts are for WCAG 2.2, the current version, and are counted from the W3C Recommendation.

The three levels at a glance

WCAG 2.2 conformance levels: criteria at each level, criteria needed to conform, and examples
Level Criteria at this level Criteria to conform at this level In plain terms
A 31 31 The minimum level of conformance, in W3C's words. It covers basics such as text alternatives, keyboard operation, page language and page titles.
AA 24 55 (all of A and AA) Adds, among others, 4.5:1 text contrast, resizing text to 200 percent, a visible keyboard focus and a 24 by 24 CSS pixel minimum target size.
AAA 31 86 (all of A, AA and AAA) The highest level. Adds, among others, 7:1 text contrast, sign language for prerecorded audio and a reading-level supplement.

The levels are cumulative: a page that conforms at AA also meets every Level A criterion. Our WCAG 2.2 criteria list shows the level of every one of the 86 criteria, and the 55 Level A and AA criteria are listed together.

How the counts differ by WCAG version

The number of criteria needed for AA conformance has grown with each version. W3C does not print per-level totals for any version, so we counted them ourselves from each Recommendation. The counts are consistent with the changes W3C lists: WCAG 2.1 added 17 criteria, and WCAG 2.2 added 9 and removed 4.1.1 Parsing.

Success criteria at each level in each WCAG version (GotAlt's count from each W3C Recommendation)
Version Level A Level AA Level AAA All levels A and AA together
WCAG 2.0 25 13 23 61 38
WCAG 2.1 30 20 28 78 50
WCAG 2.2 31 24 31 86 55

Because each version keeps the earlier criteria, a page that conforms to WCAG 2.2 also conforms to 2.0 and 2.1, with one caveat about 4.1.1 Parsing that which WCAG version the law requires explains.

What conformance at a level requires

Meeting the criteria is the core of it, but W3C sets five conformance requirements that all have to be satisfied (WCAG 2.2, section 5.2). In plain terms:

  1. Meet the level in full. Level A means all Level A criteria. Level AA means all Level A and Level AA criteria. Level AAA means all three sets. W3C notes that conformance "can only be achieved at the stated levels," so meeting 54 of the 55 criteria at A and AA is not AA conformance, although authors are encouraged to report progress beyond the level they reached. A conforming alternate version of a page can stand in for the page itself.
  2. Cover whole pages. Conformance is for full pages and cannot be achieved if part of a page is excluded. Every variation a responsive page presents for different screen sizes has to conform.
  3. Cover complete processes. When a page is one step in a process, such as checkout, every page in the process has to conform at that level or better.
  4. Rely only on accessibility-supported technologies. The criteria can be met only by technologies used in accessibility-supported ways, and anything provided in an unsupported way must also be available in a supported one.
  5. Do not interfere. Technology used in an unsupported or non-conforming way must not block access to the rest of the page. Four criteria apply to all content on the page, even content not relied on for conformance: 1.4.2 Audio Control, 2.1.2 No Keyboard Trap, 2.2.2 Pause, Stop, Hide and 2.3.1 Three Flashes or Below Threshold.

A conformance claim is optional: authors can conform without making one. A claim states the date, the guidelines and version, the level, the pages it covers and the technologies relied on (WCAG 2.2, section 5.3). For pages that will carry content the author does not control, such as comments or ads inserted over time, W3C describes a statement of partial conformance (section 5.4). See also W3C's Understanding Conformance.

How W3C decided which criteria sit at which level

W3C's Understanding Levels of Conformance says the working group assigned each criterion to a level after weighing several interacting factors. They include whether content that fails could be fixed automatically by assistive technology, whether workarounds exist, whether the criterion can be satisfied for every kind of website and content, whether the skills it needs could be learned in a week's training or less, whether it limits functionality or visual design, and how much interpretation is needed to judge it.

W3C's own example: criteria that cannot be worked around, can be met by all content, need no specialized skills and need no fundamental change to functionality or design would likely land at Level A. Criteria that cannot be met for all content, need subjective judgment and need extensive changes would likely land at Level AAA.

Levels are not a ranking of severity

W3C says WCAG 2 "does not suggest any particular level of priority or severity." Failing a Level AA criterion is not necessarily less harmful to a user than failing a Level A one, because impact depends on how often the failure occurs and on the kind of content it affects. W3C also calls the choice of which level to aim for "fundamentally a policy decision." The levels tell you what a law or contract is asking for, not which fix matters most first. For that, start from the failures that occur most, which our guide to the most common accessibility errors covers.

Examples of criteria at each level

Examples of WCAG 2.2 success criteria at each level, with what each asks for
Success criterion Level What it asks for
1.1.1 Non-text Content A Every image, icon, chart or other non-text item has a text alternative that does the same job, and purely decorative images are hidden from assistive technology.
2.1.1 Keyboard A Everything can be done with a keyboard alone, without precise timing, unless the function depends on the path of movement, such as freehand drawing.
2.4.2 Page Titled A Each page has a title that describes its topic or purpose.
3.1.1 Language of Page A The main language of each page is declared in code, for example a lang attribute on the html element.
1.2.4 Captions (Live) AA Live video with sound carries captions in real time.
1.4.3 Contrast (Minimum) AA Text has a contrast ratio of at least 4.5:1 against its background, or 3:1 for large text. Logos, decoration and inactive controls are exempt.
1.4.4 Resize Text AA Text can be enlarged to 200 percent without assistive technology and without losing content or function. Captions and images of text are excepted.
2.4.7 Focus Visible AA Keyboard users can see which element has focus.
2.5.8 Target Size (Minimum) AA Pointer targets are at least 24 by 24 CSS pixels, or spaced so that small targets do not crowd each other, with exceptions for equivalent controls, targets in text, browser-controlled and essential targets.
1.2.6 Sign Language (Prerecorded) AAA Recorded audio in video has sign language interpretation.
1.4.6 Contrast (Enhanced) AAA Text has a contrast ratio of at least 7:1 against its background, or 4.5:1 for large text, with the same exemptions as 1.4.3.
2.2.6 Timeouts AAA Users are warned how long they can be inactive before data is lost, unless the data is kept for more than 20 hours.
3.1.5 Reading Level AAA When text needs reading ability beyond lower secondary education, supplemental content or a simpler version is available.

The same topic at two levels

Some subjects appear at both AA and AAA, with the stricter requirement at AAA. Three pairs show how the levels differ in practice.

Subjects that WCAG 2.2 covers at Level AA and again, more strictly, at Level AAA
Subject Level AA requirement Level AAA requirement
Text contrast 1.4.3: at least 4.5:1, or 3:1 for large text 1.4.6: at least 7:1, or 4.5:1 for large text
Pointer target size 2.5.8: at least 24 by 24 CSS pixels, with spacing and other exceptions 2.5.5: at least 44 by 44 CSS pixels, with exceptions
Keyboard focus 2.4.7: a visible keyboard focus indicator exists 2.4.13: the indicator has a minimum area and at least 3:1 contrast between its focused and unfocused states

Why laws name Level AA

This page is general information, not legal advice. Read the source for the law that applies to you and ask a lawyer about it. Every law or rule in our table of WCAG versions that names a level names AA, and Section 508 names Levels A and AA, which together are the same set of criteria as AA conformance:

None of the laws in our table names Level AAA, and some name no level at all: ADA Title III has no web regulation. The table of laws and the WCAG version each names has the full list with sources.

We have not found a primary source in which a legislature or agency explains why it chose AA, so we do not offer a reason for any one law. What W3C's own text does show is why a level above AA is a poor fit for a blanket rule, covered next, and that the choice of level is a policy decision rather than a technical one. For each country, see web accessibility laws worldwide.

Should you aim for AAA?

W3C's note on this reads: "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" (WCAG 2.2, section 5.2.1, note 2). That is a statement about blanket requirements, not a warning against AAA criteria. W3C also encourages authors to report progress beyond the level they conform at, and the practical route is to pick the AAA criteria that suit your content, such as 7:1 contrast for body text or larger targets on touch interfaces, and to treat them as additions to an AA baseline.

W3C adds, in the introduction to WCAG 2.2, that even content conforming at AAA will not be accessible to people with all types, degrees or combinations of disability, particularly in the cognitive, language and learning areas. A level describes conformance to written criteria. It is not a measure of how usable a page is for everyone.

Which level should you target?

If a law or contract names a version and a level, that is your minimum, and the source of the requirement is the place to read it. Where nothing names one, building to WCAG 2.2 Level AA covers the Level A and AA criteria of 2.0 and 2.1 as well, since W3C says content that conforms to WCAG 2.2 also conforms to 2.0 and 2.1 (keep the 4.1.1 caveat above in mind). A checker or scan cannot tell you whether you have reached a level: software can decide only 3 of the 86 criteria for most content, as how much of WCAG can be automated sets out, so conformance at any level needs testing with people. Our WCAG 2.2 checklist walks through the criteria.

What we don't claim

W3C does not print totals per level, so every count on this page is our own count from the W3C Recommendations. No scan, audit or checklist from GotAlt or anyone else makes a site conform at any level, and our free scan reports only the failures a machine can find. See what we check and what we cannot and our editorial policy.

Questions about WCAG levels A, AA and AAA

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

They are three cumulative sets of success criteria. Level A is the minimum level of conformance, AA adds 24 criteria in WCAG 2.2 for a total of 55, and AAA adds 31 more for all 86. Each level above A asks for more, and some AAA criteria are stricter versions of AA ones, such as 7:1 contrast instead of 4.5:1.

How many success criteria are at each level?

In WCAG 2.2, 31 are at Level A, 24 at Level AA and 31 at Level AAA, counted from the W3C Recommendation. Conforming at AA means all 55 at A and AA. WCAG 2.1 has 50 at A and AA together and WCAG 2.0 has 38, by our count.

Which WCAG level do I need?

It depends on the law or contract that applies to you. Every law in our table that names a level names AA, and none names AAA. Read the source for the version and level in your case, which which WCAG version the law requires collects, ask a lawyer how it applies, or answer a few questions in the which accessibility laws apply to me tool.

Is Level A enough?

W3C calls Level A the minimum level of conformance. The laws and rules in our table that name a level name AA, and Section 508 names Levels A and AA, so Level A alone does not meet them. Whether A is enough for you depends on the requirement that applies, so read its source.

Does any law require Level AAA?

None of the laws in our table names Level AAA. W3C says that requiring AAA as a general policy for entire sites is not recommended, because some content cannot satisfy every AAA criterion.

Is failing a Level AA criterion less serious than failing a Level A one?

Not necessarily. W3C says WCAG 2 does not suggest any particular level of priority or severity, and that impact depends on aspects such as how often a failure occurs and the type of content it affects. The level shows which set a criterion belongs to, not how much harm a failure causes.

Can I conform for only part of my site?

A conformance claim can cover one page, a series of pages or multiple related pages. But conformance is for full pages and cannot be achieved if part of a page is excluded, and when a page is one step in a process, such as checkout, every page in the process has to conform at that level or better.

See which A and AA criteria a scan can check on your site

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