What is WCAG 2.1?
WCAG 2.1 stands for Web Content Accessibility Guidelines 2.1. It is a technical standard produced by the World Wide Web Consortium (W3C) through its Web Accessibility Initiative, and it defines how to make web content usable by people with disabilities: people who are blind or have low vision, are deaf or hard of hearing, have limited mobility or dexterity, or have cognitive and learning disabilities.
The standard is deliberately written to be testable. Each requirement is a success criterion phrased as a pass or fail statement about a page, not as advice. That is what allows WCAG 2.1 to be referenced directly in procurement contracts and in law.
WCAG 2.1 became a W3C Recommendation - the W3C's final, ratified status - on 5 June 2018. It extends WCAG 2.0 (December 2008) rather than replacing it.
The 4 principles and 13 guidelines
Every success criterion in WCAG 2.1 sits under one of four principles, remembered by the acronym POUR. Under the principles sit 13 guidelines, which are broad goals, and under those sit the 78 testable criteria.
| Principle | What it means | Guidelines |
|---|---|---|
| 1. Perceivable | Information and interface components must be presentable in ways users can perceive. Nothing may be invisible to all of a person's available senses. | 1.1 Text Alternatives · 1.2 Time-based Media · 1.3 Adaptable · 1.4 Distinguishable |
| 2. Operable | Interface components and navigation must be operable. Users must be able to work the controls, by whatever input they use. | 2.1 Keyboard Accessible · 2.2 Enough Time · 2.3 Seizures and Physical Reactions · 2.4 Navigable · 2.5 Input Modalities |
| 3. Understandable | Information and the operation of the interface must be understandable. Content should not be beyond a user's comprehension, and behaviour should be predictable. | 3.1 Readable · 3.2 Predictable · 3.3 Input Assistance |
| 4. Robust | Content must be robust enough to be interpreted reliably by a wide variety of user agents, including assistive technologies. | 4.1 Compatible |
Guideline 2.5 Input Modalities is new in WCAG 2.1. It is the group that covers touch, pointer gestures and device motion, which is why 2.1 is often described as the mobile update to WCAG. Every criterion is listed in plain English in the criteria library.
Levels A, AA and AAA
WCAG 2.1 defines three conformance levels. They are cumulative: to claim AA you must satisfy every Level A criterion as well.
| Level | Criteria at this level | Cumulative total | In practice |
|---|---|---|---|
| A | 30 | 30 | The floor. Failing Level A usually means some users cannot complete a task at all. |
| AA | 20 | 50 | The level laws and contracts ask for. Removes the major barriers for most users. |
| AAA | 28 | 78 | The W3C itself states that AAA conformance is not achievable for some content, and does not recommend it as a general policy for entire sites. |
What WCAG 2.1 Level AA requires
When a regulation, an RFP or a customer contract says "WCAG 2.1 AA", it means the 50 success criteria at Level A plus Level AA. These are the requirements that generate the most work in practice:
- Contrast (1.4.3, 1.4.11). Body text needs a contrast ratio of at least 4.5:1 against its background, large text 3:1. Since 2.1, user interface components and meaningful graphics also need 3:1.
- Reflow (1.4.10). Content must work at 320 CSS pixels wide without two-dimensional scrolling. This is what makes a desktop-only layout a failure.
- Text spacing (1.4.12). Nothing may break when a user overrides line height, paragraph spacing and letter spacing.
- Keyboard operation (2.1.1, 2.4.7). Every function must be reachable and usable by keyboard alone, with a visible focus indicator.
- Captions and audio description (1.2.2, 1.2.5). Pre-recorded video needs captions, and audio description for visual information not conveyed in the audio.
- Names, roles and values (4.1.2) and status messages (4.1.3). Custom components must expose what they are and what state they are in, and dynamic updates must be announced without stealing focus.
- Orientation and input purpose (1.3.4, 1.3.5). Do not lock content to portrait or landscape, and identify common form fields so browsers can autofill them.
The answer to "which login and registration interfaces are fully compliant with WCAG 2.1 Level AA" is that no product is compliant on its own. Conformance is a property of a page as delivered, including your own content, styling and code. A sign-in flow conforms when every criterion above passes on that specific flow.
The 17 new success criteria in WCAG 2.1
WCAG 2.0 had 61 success criteria. WCAG 2.1 added 17, bringing the total to 78. Five are Level A, seven are Level AA and five are Level AAA.
| Criterion | Name | Level | What it addresses |
|---|---|---|---|
1.3.4 | Orientation | AA | Content must not be restricted to a single display orientation. |
1.3.5 | Identify Input Purpose | AA | Common input fields must be programmatically identified so they can be autofilled. |
1.3.6 | Identify Purpose | AAA | Icons, regions and controls must be programmatically identifiable. |
1.4.10 | Reflow | AA | Content reflows to 320 CSS pixels without two-dimensional scrolling. |
1.4.11 | Non-text Contrast | AA | 3:1 contrast for interface components and meaningful graphics. |
1.4.12 | Text Spacing | AA | No loss of content when users override text spacing. |
1.4.13 | Content on Hover or Focus | AA | Tooltips and popovers must be dismissible, hoverable and persistent. |
2.1.4 | Character Key Shortcuts | A | Single-character shortcuts must be switchable or remappable. |
2.2.6 | Timeouts | AAA | Users must be warned about data loss from inactivity. |
2.3.3 | Animation from Interactions | AAA | Motion animation from interactions can be disabled. |
2.5.1 | Pointer Gestures | A | Multipoint or path-based gestures need a single-pointer alternative. |
2.5.2 | Pointer Cancellation | A | Actions must not fire on down-event alone, so a mistaken press can be aborted. |
2.5.3 | Label in Name | A | The accessible name must contain the visible label text. |
2.5.4 | Motion Actuation | A | Functions triggered by device motion need a conventional alternative. |
2.5.5 | Target Size (Enhanced) | AAA | Touch targets at least 44 by 44 CSS pixels. |
2.5.6 | Concurrent Input Mechanisms | AAA | Do not restrict which input method can be used. |
4.1.3 | Status Messages | AA | Status changes are announced to assistive technology without moving focus. |
W3C status and official documents
WCAG 2.1 is a W3C Recommendation, the highest maturity level in the W3C process, reached on 5 June 2018. It was produced by the Accessibility Guidelines Working Group under the Web Accessibility Initiative (WAI).
Two supporting documents sit alongside the standard and are not themselves normative: Understanding WCAG 2.1, which explains the intent of each criterion, and Techniques for WCAG 2.1, which gives sufficient and advisory ways to meet them. Only the success criteria in the standard are binding when a law references WCAG 2.1.
Which laws and standards require WCAG 2.1
WCAG 2.1 Level AA is the reference point for most current digital accessibility regulation:
| Law or standard | Region | Level referenced |
|---|---|---|
| EN 301 549 | European Union | WCAG 2.1 Level AA |
| ADA Title II rule (US Department of Justice) | United States, state and local government | WCAG 2.1 Level AA, with compliance dates of 26 April 2027 and 26 April 2028 depending on entity size |
| European Accessibility Act | European Union | Applies EN 301 549, in force since 28 June 2025 |
| Section 508 | United States, federal | Currently WCAG 2.0 Level AA |
| AODA | Ontario, Canada | WCAG 2.0 Level AA, with exceptions |
The ADA itself does not name a technical standard for private businesses. In US web accessibility litigation, courts and settlements have nonetheless treated WCAG Level AA as the working benchmark, which is why most legal advice targets it.
WCAG 2.0 vs 2.1 vs 2.2
All three are backwards compatible. Content that conforms to WCAG 2.2 also conforms to 2.1 and to 2.0.
| Version | W3C Recommendation | Success criteria | Focus of the additions |
|---|---|---|---|
| WCAG 2.0 | 11 December 2008 | 61 | The original testable framework. |
| WCAG 2.1 | 5 June 2018 | 78 | Mobile and touch, low vision, cognitive and learning disabilities. |
| WCAG 2.2 | 5 October 2023 | 86 | Focus appearance, dragging alternatives, target size at AA, accessible authentication. |
WCAG 2.2 removed one criterion that existed in 2.1: 4.1.1 Parsing was deprecated because browsers now handle the underlying markup errors consistently.
How to test for WCAG 2.1
Automated tools reliably detect roughly a third of WCAG issues: missing alternative text, contrast failures, missing form labels, structural and ARIA errors. The remaining criteria - whether alternative text is meaningful, whether a keyboard order makes sense, whether an error message is helpful - require human judgement.
A defensible WCAG 2.1 audit combines three passes:
- Automated scanning across every template and page type, to catch the machine-detectable failures at scale.
- Manual expert review against each success criterion, including keyboard-only operation and screen reader testing.
- Documentation of the result, criterion by criterion, so conformance can be evidenced later. This is what an Accessibility Conformance Report (VPAT) records.
You can start with a free automated pass using the EqualWeb accessibility checker, or scan an entire site with the accessibility crawler. The full process is covered in the WCAG testing guide.
WCAG 2.1 checklist
A short pre-audit checklist that catches the most common Level AA failures:
- Every image has an alternative that conveys its purpose, and decorative images are marked as decorative.
- Body text meets 4.5:1 contrast; buttons, inputs and icons meet 3:1.
- The whole site can be operated with the keyboard alone, and the focus indicator is always visible.
- The page reflows at 320 CSS pixels wide with no horizontal scrolling.
- Headings describe the structure of the page and are used in order.
- Form fields have persistent visible labels, and errors say what went wrong and how to fix it.
- Pre-recorded video has captions; audio-only content has a transcript.
- Custom widgets expose a correct name, role and value, and status messages are announced.
- Content does not depend on colour alone, on a path-based gesture, or on device motion.
- The page has a language attribute and a descriptive, unique title.
Frequently asked questions
What does WCAG 2.1 mean?
WCAG stands for Web Content Accessibility Guidelines. The 2.1 is the version number: a 2018 update to WCAG 2.0 that added 17 success criteria covering mobile, low vision and cognitive accessibility.
What is WCAG 2.1 Level AA?
Level AA is the middle of three conformance levels. It comprises the 30 Level A criteria plus 20 more, 50 in total. It is the level referenced by EN 301 549, the ADA Title II rule and most procurement contracts.
How many success criteria are in WCAG 2.1?
78 in total: 30 at Level A, 20 more at Level AA and 28 more at Level AAA.
Is WCAG 2.1 still current, or should I target 2.2?
Both are current W3C Recommendations. Most law still points at 2.1 Level AA, so 2.1 AA remains the compliance target. Because 2.2 is backwards compatible, building to 2.2 satisfies 2.1 as well and puts you ahead of the next regulatory update.
Is WCAG 2.1 a law?
No. It is a technical standard published by the W3C. It becomes legally binding only where a law or contract references it, which many now do.
Can a widget or plugin make my site WCAG 2.1 compliant?
No single tool can. Automated technology resolves a substantial share of the machine-detectable issues, but conformance is judged on the delivered page and a meaningful proportion of the criteria require human review and remediation of the underlying code and content.
What is the difference between WCAG 2.0 and 2.1?
WCAG 2.1 contains everything in WCAG 2.0 plus 17 additional success criteria. There are no changes to the 2.0 criteria themselves, so conformance to 2.1 implies conformance to 2.0.
- W3C, Web Content Accessibility Guidelines (WCAG) 2.1, W3C Recommendation 5 June 2018 - w3.org/TR/WCAG21
- W3C WAI, What's New in WCAG 2.1 - w3.org/WAI
- ETSI, EN 301 549 - Accessibility requirements for ICT products and services - etsi.org
- US Department of Justice, ADA Title II web and mobile accessibility rule - ada.gov
Last updated . Reviewed by the EqualWeb accessibility team.
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