05 June 2024

Why is Colour Contrast Important for Web Accessibility?

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Why is Colour Contrast Important for Web Accessibility?
Gavin James-WeirWritten ByGavin James-Weir

Gavin is Propeller's Lead Designer. Since joining the team in 2011, Gav has lead the way for innovating web design and UX for Propeller and client work.

Visual elements are processed by the brain faster than text, and 90% of the information transmitted is visual. First impressions count, and this is no exception in web design. When users arrive on a website, they will decide whether to stay on your website or browse elsewhere within the first few seconds. Colours can help keep users online, deliver a message quickly, set an atmosphere and improve your content presentation. 

Aside from finding colours that reflect your brand identity, it is incredibly important to make sure your colours are visible to everyone. Colour contrast should not be an afterthought. The World Health organisation estimated there were at least 1 billion people living with some form of disability in 2021. 

In 2024, web accessibility has become essential in an era where digital leads. This article explores why colour contrast is key to promoting web accessibility.

The meaning behind web accessibility

Web accessibility describes the intentional creation and designing of websites that can be used by everyone including people with disabilities. Disabilities have different levels of severity and can have multiple impacts on someone’s way of living. With this in mind, designers must consider using colours that can be seen by the widest range of people. This means improving colour contrast between content and background so that anyone can differentiate the content and easily read your text.

Checking the Web Content Accessibility Guidelines

Otherwise know as WCAG, the Web Content Accessibility Guidelines were created to ensure that web content is accessible for everyone, despite their abilities, disabilities, and devices. Even though the WCAG is not mandatory in every country, a lot of them are allowing individuals to sue websites that do not meet the WCAG standards for discrimination. Moreover, it is, in any case, recommended to utilise the WCAG to ensure the best colour accessibility.

In order to meet the WCAG’s standards, it is vital to have the text and interactive elements with a color contrast ratio of at least 4.5:1. Such a wide contrast ratio ensures that almost everyone will be able to read any text, even people who cannot see the full colour spectrum. To make it easier for you to check whether your colour palette respects the contrast ratio or not, contrast checkers can easily be found online, for example, the WebAIM Contrast Checker or Adobe Color.

However, some specific elements may not need to follow the 4.5:1 ratio rule:

  • Any text of 14 pt bold or larger, as well as 18 pt text and larger, should have a ratio of at least 3:1.
  • Brand logos
  • Subsidiary text and text images which are used as decoration and do not serve user purpose.

Understanding colour contrast

As you have read above, colour contrast is one of the key criteria to ensure web accessibility. However, even with the existence of several online tools, is it recommended to understand how colour contrast works.

In web design, colour is used to make something stand out from the rest. To do that, you have to decide how much you want your element to stand out and in relation to which other elements. 

Contrast is how you are using colours to differentiate elements from one another. Colour contrast can be low when using an similar colour scheme or high when using opposite colours on the colour wheel.

Best practices

Several elements should be taken into account to ensure that the widest range of people can clearly see your content: 

  • Ratio: you should have a colour contrast ratio of at least 4.5:1 for text and any interactive elements.
  • Colour blindness: avoid using typical colour blindness combinations like red-green or cyan-grey.
  • Indicators: interactive elements must not have colour as their only indicator so make sure to add elements, like underlining links on hover.
  • Written style: colours must be written in formatting code like CSS so the accessibility can be accurately measured, black and white are no exception to this rule.


In Summary…

Colour contrast goes beyond surface-level aesthetics. To avoid incorporating the recommended levels of colour contrast in web design would make your website less accessible and deter users from staying online. 

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