I use a web app to check my site color contrast. Most of my color (Back/fore ground colors) are OK and I see YES inside textboxes except the one which refers to WCAG 2 AAA. What is it? What is the difference between WCAG 2 AAA Compliant and WCAG 2 AA Compliant?

2 Answers 2


The definition is very clear:

Level AA: For Level AA conformance, the Web page satisfies all the Level A and Level AA Success Criteria, or a Level AA conforming alternate version is provided.
Level AAA: For Level AAA conformance, the Web page satisfies all the Level A, Level AA and Level AAA Success Criteria, or a Level AAA conforming alternate version is provided.

Every single rule in the guideline has a level of conformance it belongs to. If you fulfill all requirements marked with AAA, your site has the highest compliance.

  • Thanks for the answer. It was helpful. If background and foreground color fail in passing Level AA, does that mean colorblind people can't see it or can see it with difficulties?
    – Alireza
    Jun 18, 2012 at 14:42
  • That depends on the actual contrast value. They will have at least some difficulties if it's too low, but sometimes the contrast is still enough to be readable but you are not compliant per definition. Test it with actually disabled people, they will give you good feedback whether you have to change it or it is already ok.
    – Michael
    Jun 18, 2012 at 15:22
  • @MarjanVenema, what do you mean? Do you mean I should mark it as an answer plus upvoting it? Is this what you're saying?
    – Alireza
    Jun 19, 2012 at 12:10
  • @UX-Geek: that is exactly what I mean. Not that you have to, but I can't imagine why one would want to accept but not upvote an answer. Jun 19, 2012 at 13:41
  • @MarjanVenema you don't upvote because when you mark an answer you give him/her +5pt and I think there is no reason to upvote him again. upvote is there for people who wants to appreciate the answer since they can't mark it as an answer. thanks by the way for mentioning it.
    – Alireza
    Jun 19, 2012 at 15:24

To answer your comment above. The background and foreground colours pass or fail on a specific algorithm, which is different for AA and AAA. An overview is given below:

AA = Contrast ratio of at least 4.5:1 between background and foreground. 3:1 for large text (over 18 point or 14 point bold)

AAA = Contrast ratio of at least 7:1 between background and foreground. 4.5:1 for large text (over 18 point or 14 point bold)

With regards your question does it mean colour blind people have difficulties, that depends on various factors. Consider checking your site on a colour blind simulator such as http://www.vischeck.com/. Personally I think the WCAG guidelines are too limiting at the lower contrast levels. Also they have no limit for high contrast. Too much contrast can often be an issue for users with dyslexia I believe.

If accessibility is core and you have budget find a way to test with users with various disabilities, as colour contrast is only a small part of accessibility. There are companies that offer these services I believe.

  • 2
    I've read in the guidlines that it's not recommended to follow the exact requirement of AAA for all of your website elements. I think it would be too difficult to reach to that point, and all of you site will look so bizzare.
    – Alireza
    Jun 19, 2012 at 12:18

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