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An Overview of WCAG Criteria – Principles, Conformance Levels, and Success Criteria Explained Clearly

The WCAG (Web Content Accessibility Guidelines) are the international standard for accessible web content. They define how text, images, links, and all other components of a website must be designed so that they can be used accessibly by as many people as possible – regardless of disabilities or cognitive impairments.

Check website now WCAG 2.2 at a glance
An overview of WCAG criteria – principles, conformance levels, and success criteria

The Key Facts at a Glance

WCAG Criteria at a Glance

These four points summarize how WCAG is structured and what matters in practice.

  • check Published by the W3C through its Web Accessibility Initiative (WAI) as an official Recommendation
  • check Hierarchical structure: four principles → 13 guidelines → individual success criteria
  • check WCAG 2.2 adds nine new success criteria to WCAG 2.1 – including focus indicators, target sizes, and authentication
  • check Compliance must be implemented in code and structure and documented in an accessibility statement – an accessibility widget alone isn't enough
WCAG criteria – the key facts at a glance
check 86 success criteria in WCAG 2.2
check Level AA is the mandatory legal standard (BFSG & EAA)
check Four principles – one clear system

What is the WCAG and how is it structured?

The Web Content Accessibility Guidelines (WCAG) are guidelines for accessible web content, published by the World Wide Web Consortium (W3C), more specifically by its Web Accessibility Initiative (WAI). The World Wide Web Consortium is the international body for web standards and publishes the WCAG as an official recommendation (W3C Recommendation). The goal of the WCAG is to design text, images, links, forms, documents, and all other web content in such a way that people with various disabilities receive equal and accessible access.

The WCAG are structured hierarchically and divided into four levels: At the top stand four overarching principles. Below them are 13 guidelines that specify what these principles mean in practice. The testable requirements are defined by success criteria – these are concrete, measurable statements about whether web content meets a requirement and is accessible to all people. Additionally, there are techniques that demonstrate how success criteria can be implemented technically – for example, using HTML or CSS.

The current version, WCAG 2.2, was published by the W3C in October 2023 and expands the predecessor version, WCAG 2.1, by nine new success criteria. It is fully backward-compatible: Whoever meets WCAG 2.2 at Level AA automatically fulfills all requirements of levels A and AA from WCAG 2.0 and 2.1. The WCAG are anchored in ISO/IEC 40500 and the European standard EN 301 549, forming the technical foundation for the BFSG and the European Accessibility Act (EAA).

The Four Core Principles of the WCAG – The POUR Model

All 86 success criteria of WCAG 2.2 can be traced back to four core principles. Text, images, links, and all other web elements of a website must fulfill all four principles – only then is a digital service considered barrierefrei and accessibly open to everyone.

1. Perceivable

Text, images, videos, and all other content must be presented so that people can perceive them with their available senses. Examples: text alternatives for images, captions for videos, sufficient color contrasts for text.

2. Operable

All functions and the entire navigation must be operable – without a mouse, via keyboard alone. No person should encounter elements that are impossible for them to operate. Focus, keyboard operation, and time limits are central requirements.

3. Understandable

Text, content, and the operation of the user interface must be understandable to all people. Plain language, consistent navigation, and helpful error messages are components of this understandable principle.

4. Robust

Text, code, and all content must be implemented robustly enough so that user agents and assistive technologies can interpret them reliably – today and with future technical developments. Example: web content that is correctly processed by new applications.

Summary

  • The WCAG are the global standard for accessible web content, structured into 4 principles (POUR), 13 guidelines, and measurable success criteria.
  • For the BFSG and the European EAA, conformance level AA (50 criteria) serves as the mandatory statutory benchmark in code.
  • The WCAG 2.2 version introduces 9 new success criteria – including critical updates for focus indicators, target sizes, and login processes.
  • WCAG compliance can be structurally monitored using automated monitoring solutions like easyMonitoring by SiteCockpit.

The Three Conformance Levels: Level A, Level AA, and Level AAA

Each success criterion is assigned to one of three conformance levels. Level A is the minimum, Level AA is the statutory standard for the BFSG and EAA, and Level AAA is the highest achievable tier. Especially for public bodies, the classification of these levels is critical.

Success Criteria
Legally Required
Practical Meaning
Level A – Minimum
30 criteria
Baseline – as a minimum alone, not sufficient for the BFSG or EAA
Eliminates the most severe barriers. Websites that do not meet Level A are simply not operable for many individuals with disabilities – for example, because text cannot be read aloud or links cannot be reached via keyboard.
Level AA – Standard
50 criteria in total (A + AA)
Mandatory: BFSG, EAA, BITV 2.0, EN 301 549
The international standard benchmark for digital accessibility. Level AA is legally binding for all companies and public bodies. It supplements Level A with requirements for text contrast, text size, focus indicators, and more.
Level AAA – Maximum
86 criteria in total (A + AA + AAA)
Voluntary – no law requires full Level AAA compliance
The highest level of digital accessibility. Level AAA is not fully achievable for all content types. It is recommended for highly sensitive areas such as healthcare or portals of public bodies.

Success Criteria in Practice – Central Requirements for Text and Content

Success criteria are the testable core statements of the WCAG. They are formulated in a technology-neutral manner and define measurably what text, images, links, forms, and all other web contents must achieve to be accessible to individuals with disabilities. Here are the criteria most frequently missing or incorrectly implemented in practice:

  • check 1.1.1 Non-Text Content (Level A): Images, icons, and graphic elements require a text alternative – the alt text must fulfill the same purpose as the visual content
  • check 1.4.3 Contrast - Minimum (Level AA): Text must feature a contrast ratio of at least 4.5:1 against the background – large text at least 3:1
  • check 1.4.4 Resize Text (Level AA): Text must be resizable up to 200% without loss of content or functionality
  • check 1.4.12 Text Spacing (Level AA): Individuals must be able to adjust line height, letter spacing, and word spacing in text without losing content
  • check 2.1.1 Keyboard (Level A): All functionalities must be operable via keyboard – entering text, following links, submitting forms
  • check 2.4.4 Link Purpose (Level A): The purpose of a link must be discernible from the link text alone – "Learn more" without context is insufficient
  • check 2.4.6 Headings and Labels (Level AA): Headings and labels must describe the topic or purpose of the text section
  • check 3.1.1 Language of Page (Level A): The default language of a document must be declared in the HTML – user agents and screen readers require this information
  • check 3.3.1 Error Identification (Level A): Automatically detected input errors must be described to the person in text
  • check 4.1.2 Name, Role, Value (Level A): All components of the user interface must be accessible to user agents and assistive technologies
Accessible design in detail
WCAG success criteria in practice – requirements for text, images, and links

WCAG 2.2 – Published October 2023

The Nine New Success Criteria in WCAG 2.2

WCAG 2.2 supplements the predecessor version WCAG 2.1 with nine new success criteria that specifically address motor and cognitive limitations as well as other disabilities. Several concern keyboard operation and focus – for individuals who cannot use a mouse, these criteria are critical in practice. Two Level A criteria and four Level AA criteria are directly relevant to the BFSG and EAA:

  • check 3.2.6 Consistent Help (Level A): Help features must be described and located identically across pages
  • check 3.3.7 Redundant Input (Level A): Individuals must not be required to enter the same text information twice in the same process
  • check 2.4.11 Focus Not Obscured - Minimum (Level AA): The focus indicator must not be completely obscured by superimposed content such as cookie banners
  • check 2.5.7 Dragging Movements (Level AA): Drag-and-drop functions require a text alternative via click or tap – ensuring operability for individuals without pointing devices
  • check 2.5.8 Target Size - Minimum (Level AA): Click targets must be at least 24×24 pixels in size or feature a minimum spacing from neighboring elements
  • check 3.3.8 Accessible Authentication - Minimum (Level AA): Login processes must not require cognitive tests like puzzles or image identification as the sole path of authentication
  • check 2.4.12 Focus Not Obscured - Enhanced (Level AAA): The focus indicator must be completely visible
  • check 2.4.13 Focus Appearance (Level AAA): Focus indicators require an outline that is at least 2 pixels thick with sufficient contrast
  • check 3.3.9 Accessible Authentication - Enhanced (Level AAA): Object identification tasks are likewise not permitted as a minimum standard
WCAG 2.2 on w3.org
The nine new success criteria in WCAG 2.2 – focus, target size, and authentication

WCAG, BFSG, and EAA – How Do They Connect Legally?

The WCAG are not a law, but a technical standard of the World Wide Web Consortium (W3C). They become legally binding through laws that reference them. The German Accessibility Strengthening Act (BFSG) has been in force since June 28, 2025, and obligates companies with at least ten employees or two million euros in annual turnover to design digital offerings, websites, web applications, and documents accessibly. As a technical yardstick, the BFSG points to EN 301 549, which establishes WCAG Level AA as the mandatory standard.

In practice: Whoever structures the text, images, links, and all other web components of their website according to WCAG 2.2 Level AA generally satisfies the technical requirements of the BFSG, EAA, and BITV 2.0. The BITV 2.0 applies additionally to federal public bodies. Important: Conformity according to Level AA must be proven and documented in an accessibility statement. An accessibility widget as a minimum is not sufficient for legal compliance – the implementation in code, layout structure, and text content remains decisive so that all people can use the website accessibly.

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Techniques vs. Success Criteria – What Is the Difference?

A frequent misunderstanding in practice: The WCAG distinguish clearly between normative success criteria and informative techniques. For text, HTML, CSS, and all other implementation details, specific techniques exist – but these are not mandatory. The decisive element remains the final outcome for all individuals:

  • check Success criteria are normative: They define bindingly what text, images, links, and forms must achieve – formulated in a technology-neutral manner and measurably accessible to all people
  • check Techniques are informative: They show how criteria can be put into practice using HTML, CSS, ARIA, or JavaScript
  • check Sufficient techniques: These methods reliably satisfy a success criterion – but the list is not exhaustive
  • check Advisory techniques: They optimize the accessibility of text and content but are not sufficient on their own to fulfill a criterion
  • check Failure techniques: Documented anti-patterns that violate at least one success criterion – for example, text implemented purely as an image without an alternative description
  • check Independent implementation is possible: Custom or undocumented techniques can also be compliant, as long as the success criterion is fulfilled for all people with disabilities – this also applies to the future development of new web applications
WCAG Techniques on w3.org
WCAG techniques vs. success criteria – the difference explained in practice

Frequently Asked Questions about WCAG Criteria

The WCAG are built hierarchically: Four principles form the top layer. Below them sit 13 guidelines that describe the respective target for text, navigation, operability, and robustness. The actual testable requirements are the success criteria – they articulate concretely and measurably what a digital product must provide for all people. Guidelines describe the objective; success criteria are the measurable yardstick for whether web content is accessible.

WCAG 2.2 adds nine new success criteria that primarily account for motor and cognitive limitations as well as other disabilities. At Level AA and thus directly relevant to the BFSG are: Focus Not Obscured - Minimum (2.4.11), Dragging Movements (2.5.7), Target Size - Minimum (2.5.8, at least 24×24 pixels), and Accessible Authentication - Minimum (3.3.8). New at Level A: Consistent Help (3.2.6) and Redundant Input (3.3.7).

WCAG techniques are informative documents by the World Wide Web Consortium (W3C) that outline how success criteria can be implemented with HTML, CSS, ARIA, or JavaScript in practice. They are non-normative and thus not legally binding. The critical aspect is that the success criterion is fulfilled for all individuals – not which specific technique is employed. Independent or novel approaches can also be compliant, such as when engineering modern web applications.

Conformance at Level AA can be verified through a combination of automated testing and manual reviews. easyMonitoring audits websites continuously for a multitude of success criteria – from missing image alternative descriptions and insufficient contrasts to elements lacking keyboard accessibility. Because automated user agents detect only about 30–40% of all potential barriers, a manual review remains necessary for a comprehensive conformity assessment. Especially for businesses and public entities, this hybrid approach is the most reliable path to truly accessible web content.