WCAG: the international standard for web accessibility

Definition

WCAG (Web Content Accessibility Guidelines) is the international standard for digital accessibility, developed by the W3C. The guidelines define how websites and digital content should be designed to be usable by people with disabilities.

What is WCAG?

The Web Content Accessibility Guidelines (WCAG) are a set of international guidelines for web accessibility. They are developed by the W3C (World Wide Web Consortium) – the organisation that defines the web's standards – and serve as the global reference point for what counts as an accessible digital experience.

WCAG is aimed at everyone who creates web content: designers, developers, content producers and product teams. The guidelines cover accessibility for people with visual, hearing, motor and cognitive impairments, but in practice they also lead to a better experience for all users.

The versions – from 2.0 to 2.2

WCAG has been published in several versions since 1999:

• WCAG 2.0 (2008) – Introduced the four core POUR principles and the three levels A, AA and AAA. Still the reference point in a good deal of legislation.
• WCAG 2.1 (2018) – Added 17 new criteria with a particular focus on mobile use and cognitive impairments. This is the version the current EN 301 549 standard (v3.2.1) is based on.
• WCAG 2.2 (2023) – The latest version, backwards compatible with 2.1. Added nine criteria, mainly for users with motor or cognitive impairments, and removed one (4.1.1 Parsing). The W3C recommends that new implementations aim for 2.2, and the new version of EN 301 549 (v4.1.1, September 2026) builds on it – but it is not yet the legal reference.

WCAG 3.0 is in development, with a different structure – but as of 2026 it is still a working draft rather than a finished standard, and it is unlikely to be released as a standard before 2027–2028.

The four core principles – POUR

All WCAG criteria build on four principles, usually abbreviated as POUR:

• Perceivable – The content must be perceivable by the user. Images need alt text, videos need captions, and colour must never be the only way information is conveyed.
• Operable – The interface must be usable. Everything must work with a keyboard, users must have enough time, and nothing may trigger seizures.
• Understandable – Content and interface must be understandable. The language must be readable, pages must behave in expected ways, and error messages must be easy to understand.
• Robust – The content must be interpreted correctly by assistive technologies such as screen readers and braille displays. That requires correct and clean HTML semantics.

The three levels – A, AA and AAA

The WCAG criteria are organised into three levels of conformance, in which each level includes all the requirements of the levels below it:

• Level A – The minimum baseline. 31 criteria. Covers the most fundamental barriers and has minimal impact on design and structure. Without these, the website is in practice unusable for many people.
• Level AA – The standard level most laws and regulations require. 31+24 = 55 criteria. Includes requirements such as correct colour contrast (at least 4.5:1), consistent navigation, visible focus indicators and a clear heading hierarchy.
• Level AAA – The highest level. 55+31 = 86 criteria (all of them under WCAG 2.2). Includes requirements such as a 7:1 contrast ratio, sign language interpretation of video and extended audio descriptions. Rarely a legal requirement, but it shows a strong commitment to accessibility.

In practice, level AA is the goal for the vast majority of organisations, and it is also the level that the EU accessibility directive, the ADA, Section 508 and most national laws refer to.

WCAG and the law – what applies in Sweden and the EU?

On 28 June 2025, the EU accessibility directive (European Accessibility Act, EAA) began to apply in all member states. In Sweden it is implemented by the Swedish Act (2023:254) on the Accessibility of Certain Products and Services (lagen om vissa produkters och tjänsters tillgänglighet), which came into force the same day. The act covers specified products and consumer services – including e-commerce, banking services, e-books and passenger transport – and does not mention WCAG. In practice, the requirements are based on the EN 301 549 standard, which the Swedish Post and Telecom Authority (PTS) refers to and which is currently based on WCAG 2.1 level AA.

Unlike the Swedish Act on Accessibility to Digital Public Services (the DOS Act, 2018:1937), which covers the public sector and still applies in parallel, the EAA also targets private business – specifically companies whose services are aimed at consumers. As a result, e-commerce companies, banks, travel companies and digital services are now subject to legal requirements in a way they were not before. Micro-enterprises (fewer than 10 employees and no more than €2 million in turnover or balance sheet total) are exempt as regards services, but not necessarily products.

Read our blog post on what the accessibility directive means for your website: The European Accessibility Act – how the law affects your website.

WCAG and SEO – an underestimated connection

WCAG requirements and good SEO practice overlap considerably. Several of the changes that make a website more accessible also directly improve how Google interprets the content:

• Alt text on images – Essential for accessibility, and a direct ranking signal for image search and semantic understanding
• A correct heading hierarchy – Creates a logical structure for screen readers and helps Google understand how the content is organised
• Clean HTML semantics – Correct use of HTML elements makes the content easier for both assistive technologies and crawlers to interpret
• Keyboard navigation and focus states – Signal technical quality and good UX – indirect ranking factors through engagement signals

Google does not count accessibility as a page experience signal of its own (Google Search Central), but most of what makes a website accessible – clear headings, alt text, readable contrast – also makes it easier to use. So an accessible website is not only ethical and lawful – it is also better for everyone who visits it.

How to test WCAG on your website

There are both automated and manual testing methods:

• Automated tools: WAVE (wave.webaim.org), Google Lighthouse, axe DevTools and IBM Equal Access Checker can identify many but not all problems. Automated tools usually catch 30–40% of accessibility problems.
• Manual testing: Navigating using only the keyboard, testing with screen readers (NVDA, VoiceOver) and reviewing colour contrast with tools such as Contrast Checker.
• User testing: Testing with actual users who have disabilities gives insights automated tools can never capture.

Full conformance requires a combination of all three – automated tools for scanning, manual review for complex interactions and human judgement for nuanced accessibility questions.