I am checking a software against the software ergonomic requirements of WCAG 2.1 Level AA. On part is the colour contrast, which must be for graphics 3.0:1. In the following graphic the orange part is for users without any disabilities very good visible, however the tool "Color Contrast Analyser" show only a contrast to the white background of 2.0:1.

So the graphic does not meet WCAG 2.1 Level AA. But what is the reason? Again: the orange part of the graphic is very good visible. Might it be an inaccuracy of algorithm for calculating colour contrast? Or is it just my personal sensation?

Any other ideas?

graphic with red, orange and green skala. medium value is 38.

1 Answer 1


Accessibility is mainly about inclusion. Think about font size for example. A kid might argue that the text doesn't need to be bigger because it can still read/see the tiniest letters. An older person looking at the same text might complain that they'd need a magnifying glass in order to read it.

In the sense of accessibility and inclusion, you should try and design with people in mind, that may have certain difficulties in seeing, hearing etc. So even if it's completely clear and visible to you, keep in mind, that it might not be that clearly visible to everyone.

Another thing to keep in mind, is that there might be some monitors/displays, that don't handle contrast very well - as it is tackled in this answer: https://ux.stackexchange.com/a/20284/127933

That being said, in your case the contrast is not that big of a problem (though it's still not ideal), since that orange segment is just one part of an otherwise perfectly visible component. Therefore, it shouldn't be as easily overlooked as a singular poorly-contrasted object on its own. Gestalt principles, especially the law of closure is working in your favor here.

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