Understanding WCAG 2.1 Level AAA

In our first post about WCAG 2.1 Level AAA, we discuss why it is useful and when to consider including it. You can also read about how some Level AAA Success Criteria expand upon Level A and Level AA Success Criteria and how to test them in our second post, Testing WCAG 2.1 Level AAA, and what to do with your test results in our third post, Triaging WCAG 2.1 Level AAA.

The Web Content Accessibility Guidelines (WCAG) are a set of recommendations for making websites and applications accessible to people with disabilities. At the core of WCAG are testable requirements known as Success Criteria or SC for short.

There are seventy-eight success criteria in total, with each one assigned a level. There are three levels in WCAG 2.1, Level A (the lowest level), Level AA, and Level AAA (the highest level). These are usually pronounced as 'single A', 'double A', and 'triple A' in spoken English. Each level builds on the one before. To be conformant with Level AA a site or application must also be conformant with Level A.

Usually, sites and applications are expected to conform with the Level AA standard. Where accessibility laws reference WCAG , for example in Europe and North America, it is almost always to Level AA. While Level AAA contains SC that are beneficial to a wide range of people, it is generally not possible to meet Level AAA in all circumstances. WCAG includes a note that explains this:

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.

So, if that's the case, what is the point of the Level AAA Success Criteria? Conformance to any standard, such as WCAG, should be considered a minimum. It is not a gold standard of accessibility. There is always more that can be done to make our websites and applications both accessible and more usable. Some of the extra things that we can do are in Level AAA.

Level AA is required by most laws around the world rather than Level AAA. This is because the success criteria at that Level Are achievable in all circumstances. Level AAA is not always realistically achievable. It would therefore be unreasonable to require conformance to it. However, we can use it for valuable suggestions on improving accessibility and usability beyond the minimum.

Why consider Level AAA SC?

Considering Level AAA SC can have several benefits. While Level A and Level AA SC give a good foundation, Level AAA SC contains both new types of criteria and criteria that build on Level A or Level AA criteria. For example, there is a new SC for reading levels and an SC that enhances the Level AA SC for text contrast. Both the new SCs and enhanced SCs can be particularly beneficial if your audience includes people who are older or have disabilities or learning difficulties such as dyslexia. As already noted, WCAG Level AA compliance is a minimum requirement. Achieving compliance against SC 1.4.6 Contrast (Enhanced) on a site for people with low vision could make a real difference over SC 1.4.3 Contrast (Minimum).

It's worth noting that for an existing website or application, you may already be meeting many Level AAA SC. Several of them build on the requirements at Level A or Level AA. Others are often achieved by following good web design and development practices. By assessing your project against Level AAA, you gain information you can use in accessibility statements, marketing material, or product pitches. It demonstrates a commitment to accessibility that is increasingly becoming important to customers.

When to consider Level AAA SC?

Accessibility is best considered at the start of a project, whether building a new site from scratch or adding a new feature. It's worth investing some time at this stage to see which Level AAA SC might apply and which you want to meet. Incorporating Level AAA success criteria from the start is much easier than trying to retrofit your project later. For example, if you decide to meet the requirements of SC 1.4.6 Contrast (Enhanced), choosing colour combinations that have a contrast ratio of 7:1 for regular sized text from the start is easier than choosing non-conforming colours and then updating the design at a later date. Editorial is also difficult to change later. Setting requirements for language early means you don't have to do rewrites later.

For existing projects, an assessment against Level AAA can give you ideas on how to improve. You can make informed decisions about fixing any of the SC that you've not passed. It may be that none of them applies to your project, or they may not be possible to achieve realistically.

Every failure you turn into a pass is an improvement to the accessibility and usability of your site. While there will always be more you can do, WCAG Level AAA is an excellent place to look for ideas.

More information

Find out how we went about meeting WCAG Level AAA on the TetraLogical website, or how assessments can help you identify issue.

Updated 21 April 2023.

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