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Rule n° 177 - Content is presented with sufficient contrast to its background.

At first glance this is a rule intended only for disabled, colour-blind or visually impaired users. But make no mistake: a web page with sufficient contrasts is more enjoyable for everyone.

#Presentation #Design #Accessibility


  • Provide good readability of your content.
  • Limit the mental load while reading.
  • Improve the accessibility of content for people with disabilities.


Be sure to maintain a minimum contrast ratio of 3: 1 between text and its background, as measured using the WCAG2.0 algorithm.


On all pages:

  • Identify content where the difference in contrast/brightness with the background may be insufficient
  • Use a tool such as Color Contrast Analyzer to calculate the contrast ratio: click on Brightness and note the foreground colour then the background colour in the fields for this;
  • Check that the contrast ratio recorded is greater than or equal to 3:1

In the case of text on a graduated, patterned or photographic background, take the colour measurement of the background at the most unfavourable point adjacent to the text (for black text, the darkest pixel). It is advisable also to consider that the user may enlarge the character size (only zoom the text), which may cause a change in the text/background overlay.

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