Web Content Accessibility Guidelines: WCAG by the Numbers

guidelines for WCAG

When the first version of the Web Content Accessibility Guidelines (WCAG) was published in 1999 by the World Wide Web Consortium (W3C), it was the result of an international collaboration by experts in digital accessibility. Knowing that many people with disabilities around the world were reporting difficulties using inaccessible websites, these experts felt it was important to provide a comprehensive resource that could be followed to remove barriers and be inclusive of people with disabilities online.

In the fact sheet that was released alongside WCAG 1.0, the authors of WCAG observed that 10 to 20 percent of the population has disabilities, and these disabilities can often affect the way people access information technologies.

They noted: “The number of people using the Web is steadily increasing, and for people with disabilities, access to this technology is sometimes even more critical than for the general population, which may have an easier time accessing traditional sources of information such as print media.1

That was 1999. There’s been even more change since then. As we approach 2019, let’s take a look at WCAG by the numbers.

Versions of WCAG: 3

WCAG 1.0 was replaced by WCAG 2.0 in December of 2008. The new guidelines could be more easily applied to a wider variety of existing and future technologies. (It was clear by now that new technologies were being developed all the time, and it was becoming more difficult to predict what might be in widespread use.)

The 61 success criteria in WCAG 2.0 can be systematically checked through web accessibility testing. Testing for conformance matters because increasing numbers of policies and laws (such as Section 508 of the Rehabilitation Act, Accessibility for Ontarians with Disabilities Act (AODA), and EN 301 549) are now requiring compliance with WCAG 2.0.

When the third version of WCAG, version 2.1 was released in June of this year, it did not replace WCAG 2.02. Rather, it includes all of the same success criteria as in 2.0, but also covers 17 new success criteria. These new sections of the guidelines are intended to help people with low vision (that is, people who have some level of usable vision), people with cognitive disabilities, and people with learning disabilities. They’re also meant to remove more online barriers from mobile technologies.

WCAG 2.0 (12 Guidelines)WCAG 2.1 (1 Additional Guideline = 13)TOTAL WCAG 2.0 and 2.1 Success Criteria
Level A – the most basic web accessibility features25530
Level AA – deals with the biggest and most common barriers for disabled users13720
Level AAA – the highest (and most complex) level of web accessibility23528

The 2.1 version won’t be the last, by any means. Already, W3C’s Accessibility Guidelines Working Group is exploring a 3.0 version of WCAG, known as “Silver,” that would provide more guidance for removing barriers from apps. In the meantime, they’re suggesting we may one day see a WCAG 2.2 update.

Principles of Accessibility: 4

WCAG is based on four principles of accessibility, with requirements grouped under these principles. If a web page or document contains barriers to achieving any of these four principles, then the page is considered inaccessible to people with disabilities. The four principles are:

  • Perceivable. The contents of the page must be detectable to everyone, no matter what their disability. They can’t be hidden from people who can’t see small print, for example.
  • Operable. All users must be able to interact with the components of the page. A website mustn’t provide buttons that can only be clicked by using a mouse, since some people with disabilities can’t use a mouse, and instead use a keyboard, voice control or some other interface.
  • Understandable. All users must be able to understand the meaning of the information on the page, as well as the instructions for interacting with the page’s components.
  • Robust. No matter what a web page looks like or what it contains, it has to remain accessible – able to be used and understood – on a wide variety of devices and using a wide range of assistive technologies, like screen readers. It must also remain accessible as more advanced technologies and devices are developed and used.

Levels of WCAG Conformance: 3

The three levels of conformance to WCAG 2.0 and 2.1 are known as A, AA and AAA. Level A is a minimum level of accessibility. It won’t meet the needs of all people with disabilities. Level AA is used the most, as it generally provides accessibility for most people. Level AAA is the highest standard of accessibility, and while this is a worthy goal, it is not always achievable in certain circumstances.

Right now, most digital accessibility policies and laws around the world refer to WCAG 2.0, Level AA, as the requirement to follow.

Success Criteria: 78

The success criteria listed in WCAG 2.0 and 2.1 are your basis for knowing whether or not your digital technology truly is accessible. If criteria are met, then your accessibility efforts have been a success. WCAG 2.0 contains 61 success criteria and, as we mentioned above, the 2.1 version brings us 17 more, endeavouring to meet the needs of a wider variety of people with disabilities.

Examples of success criteria include:

  • Providing captions for audio tracks, so that people who are deaf will understand audio information such as dialogue and sound effects.
  • Ensuring that text can be resized (enlarged) without disrupting the way the page displays or is used, so that people with vision disabilities will easily be able to magnify what’s on their screens.
  • Turning off or extending time limits on tasks, so that people who need more time to fill out a form or make a selection won’t be excluded.
  • Designing components to be in consistent places on different pages of a website, so people will always know where they can find these components as they navigate through the website.

The success criteria are supported by a long list of techniques. These techniques were written in order to give web developers and designers a few helpful ideas for meeting the success criteria.

The Takeaway

These numbers certainly demonstrate that WCAG 2.0 and 2.1 have been well and thoughtfully organized. They’re designed to be easy to understand and follow. The Accessibility Guidelines Working Group has also produced helpful supporting material.

As you strive for accessibility in your digital technology, should you be adhering to the requirements of WCAG 2.0 or WCAG 2.1? It’s important to remember that following 2.1 doesn’t mean ignoring 2.0. The newest version of WCAG is an enhancement that is backwards compatible, meaning it includes everything in 2.0 plus add-ons that will make a real difference to many more people.

If your goal is to be as accessible as possible, then WCAG 2.1 will help you achieve that. If your goal is to comply with regulations that specifically refer to WCAG 2.0, then you may prefer to stick with this version.

But keep in mind that you can follow WCAG 2.1 and still be in compliance with the law. In fact, future laws or updates may well require compliance with the most recent version of WCAG – whatever that may be.

An Innovative Solution

eSSENTIAL ACCESSIBILITY has developed a comprehensive accessibility solution to help organizations follow the Web Content Accessibility Guidelines (WCAG) and achieve and maintain compliance with standards and regulations. This includes integrating web compliance evaluation and remediation services with assistive technology to deliver a transformative experience for people with disabilities. Learn more about eSSENTIAL ACCESSIBILITY’s innovative solution.


  1. Fact Sheet for “Web Content Accessibility Guidelines 1.0 W3C, 1999
  2. Web Content Accessibility Guidelines (WCAG) 2.1 W3C, 2018

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