Colour and colour contrast: accessibility for developers

  • Author: Access iQ ®
  • Date: 1 Feb 2013
  • Access: Premium

Quick facts

Colour is an important element of web design and is used in web development in a number of ways. Alongside size, shape and position, colour can visually communicate a great deal to users.


  • Don't use colour alone to convey meaning
  • Use a sufficient contrast ratio
  • User controlled colour contrast

Colour is an important element of web design and is used in web development in a number of ways. Alongside size, shape and position, colour can visually communicate a great deal to users.

Colour has another positive quality that it can be expressed in code as well as with images, but assistive technologies are not adept at communicating colour, other than by description, just yet. As a result it is often used to deliver information, label controls, signify status or condition or otherwise alert the user to something important. It is common to colour labels or required fields red or to signify positive or negative status with red or green icons.

When a form on a webpage tells the user that fields with a red background must be completed, colour is being used to convey instructive information that is critical to the successful completion of the form. Unfortunately, if required fields are described using colour alone, that information is not available to people who are blind, colour blind of low vision or cannot otherwise accurately perceive colour. In order to be accessible, it is necessary that important information and controls are not conveyed by one sensory modality alone.

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