Accessible Colours: A Complete Guide for Web Design

Colour is a powerful tool. It affects mood, catches attention, and can even be used to influence purchase decisions(opens in a new tab). Yet, people don’t perceive colour the same way. 

Roughly 2.2 billion people globally(opens in a new tab) are affected by some type of visual impairment that impacts how they perceive colour. This may make it difficult — if not impossible — for these individuals to access or understand information conveyed solely by colour. 

Making colours accessible ensures these individuals can navigate and use your site effectively. More importantly, it can be the difference between a well-designed, easy-to-navigate site and one that is completely illegible.

From minimum contrast ratios to the proper use of colour to communicate information, we’ll provide clear instructions and best practices for making accessible colour choices.

Accessible Colours and Colour Contrast: Definitions and Examples

The first step to creating accessible colour is understanding that colour contrast is just one part of what makes colours accessible. 

Colour contrast is the difference in light between a foreground element (like text or buttons) and its background. Users with visual impairments need a minimum level of contrast between these two elements to differentiate between them. Colour contrast is usually expressed as a ratio, with a higher number representing a higher degree of contrast between the two colours.

For example, black and white has a higher colour contrast ratio of 21 to 1. Red and white, on the other hand, have a contrast ratio of 3.9:1. This violates the Web Content Accessibility Guidelines(opens in a new tab) (WCAG), which requires webpages to have a minimum contrast ratio of 4.5:1. 

Comparison of two web page designs: left with high contrast (21:1, black and white), right with low contrast (3.9:1, red and white).

But meeting a contrast ratio alone doesn’t make your colours fully accessible. Colour accessibility goes further — it considers how people perceive colour, the context in which colours appear, and how colour is used to communicate meaning.

For example, relying on colour alone to signal an error (like turning a form field red) can be invisible to someone with colour blindness, no matter how strong the contrast is. Accessible colours address these scenarios so that your site is navigable and understandable for users across the full range of visual abilities. 

Both colour contrast and accessible colours impact the usability and inclusivity of your digital content. Accessible colour contrast ensures web elements are easily distinguishable, which helps with readability. Using accessible colours ensures that users with varying visual impairments can engage with content. 

The bottom line: finding the right colour contrast ratio and using accessible colours across your site improves the user experience, aligns with accessibility design best practices, and creates an inclusive online environment for all users. 

WCAG Guidelines for Accessible Colours

WCAG includes specific colour requirements because colour is one of the most common ways information is communicated visually — and one of the easiest places for accessibility to break down. If a user can’t perceive a colour difference, they may miss critical content, from error messages to navigation ones. 

WCAG organizes its colour guidance across three levels of conformance, each building on the last:

• Level A establishes the baseline. At this level, colour cannot be the only visual means of conveying information, indicating an action, or distinguishing an element. For example, a form that marks required fields only with red text would fail Level A because it relies on colour alone to communicate meaning.

• Level AA adds contrast requirements. Normal text and large images must meet a minimum contrast ratio of 4.5:1 against their background, and large text must meet at least 3:1. This is the level most organizations target — and is the standard referenced by major accessibility laws, including the Americans with Disabilities Act (ADA), the European Accessibility Act, and the Accessibility for Ontarians with Disabilities Act, and the Equality Act 2010 and the Public Sector Bodies (Websites and Mobile Applications) Accessibility Regulations 2018. Put simply, this ratio strikes a practical balance between visual design flexibility and broad usability. 

• Level AAA raises the bar further, requiring a contrast ratio of at least 7:1 for normal text and 4.5:1 for large text. While not always feasible across an entire site, it’s worth pursuing for key content where readability is critical. 

As a more general rule, aim for Level AA as your design baseline. The higher the contrast ratio, the more accessible — and usable — your content becomes for everyone.

Best Practices for Accessible Colours

Accessible colour isn’t just about passing a contrast check — it’s about making deliberate design decisions that support readability, hierarchy, and usability for every visitor. The best practices below will help you build that thinking into your colour choices from the start.

Choose Colour Combinations with Purpose

Strong colour combinations create enough contrast for readability while establishing a clear visual hierarchy — helping users quickly distinguish headings from body text, active buttons from disabled ones, and content from background.

Pair colours from opposite ends of the lightness spectrum. Dark text on a light background is the most universally readable combination. Complementary pairings like blue and orange can also work well, but always verify the specific shades, since not all variations will meet accessibility thresholds.

Some visually appealing combinations can create real barriers. Red and green pairings are a common example — it's a natural pairing for "good" and "bad," but it's nearly indistinguishable for users with the most common forms of colour blindness. Similarly, light gray text on a white background may look sleek, but it often falls below the 4.5:1 contrast ratio and can be difficult to read, even for users without visual impairment.

Make Text Readable in Context

Contrast ratios give you a baseline, but true readability depends on how your text works within the full design. Font size, weight, and spacing all interact with colour — a thin, lightweight font needs stronger contrast than a bold one to remain legible.

Watch how your palette performs across real scenarios. Text over images or gradients can shift in contrast across the page, so adding a semi-transparent overlay or solid text container can help maintain consistency. And be cautious with high-saturation pairings — bright blue on bright red, for example — which can create a vibrating effect that causes visual strain and may push users away from your site.

Using Colour to Communicate Information

Colour is one of the most intuitive ways to communicate meaning in a design — a red badge signals urgency, a green checkmark confirms success, a blue link invites a click. But when colour is the only way that meaning is communicated, it becomes invisible to anyone who can't perceive the difference.

This is the core principle behind WCAG Level A: colour cannot be the sole visual means of conveying information, indicating an action, or distinguishing an element.

In practice, this comes up more often than you might expect. A form that highlights errors only by turning the field border red gives no signal to a user with colour blindness. A chart that differentiates data sets only by colour becomes unreadable without it. The fix in both cases is the same — pair colour with a second visual cue. Add an icon or text label to that error state. Use patterns, varied line styles, or direct labels alongside colour in your data visualizations.

A helpful test: convert your design to grayscale. If you can still understand every element, your use of colour is on the right track.

How to Check if Your Colours are Accessible

Following the best practices above is a great starting point for creating accessible colours. However, a colour contrast checker enables you to maximize accessibility and meet accessibility standards. These tools analyze colour contrast ratios and compare them against WCAG conformance levels to ensure they're accessible.

Several colour contrast checkers are available, ranging from browser-based tools to more comprehensive auditing platforms. AudioEye's Colour Contrast Checker, for example, measures the contrast between background and foreground colours of a web page or other web elements to ensure they meet WCAG conformance standards. Unbalanced colours or inaccessible colour combinations are flagged in a shareable report, along with recommendations for resolving them. 

Whatever tool you choose, the goal is the same: enhancing the overall accessibility of your digital content and creating a more positive experience for users.

Why Accessible Colours Matter

Accessible colours play a critical role in ensuring accessibility and usability for all users — regardless of their visual abilities. As we mentioned above, your site’s colour palette can be the difference between a site that is easily readable and navigable and one that’s difficult to use, particularly by those with visual impairments, colour blindness, or other disabilities.

Accessible colours benefit those without disabilities as well. For example, older adults with age-related vision changes, or those reading on low-resolution screens, benefit from an accessible colour palette. Situational disabilities, such as being in bright sunlight or dimly lit environments, can still be read if the content has the right colour scheme and enough contrast.

Ultimately, accessible colours not only enhance usability but also contribute to a more inclusive online environment where everyone can access and engage with online content.

Create Accessible Colours with AudioEye

Accessible colours improve more than compliance — they improve the overall usability and experience of your website for every visitor. By choosing purposeful colour combinations, ensuring text is readable in context, and never relying on colour alone to communicate meaning, you can create a site that's both visually compelling and genuinely inclusive.

A colour contrast checker is one of the easiest ways to put these principles into practice. AudioEye's Colour Contrast Checker is free and measures your colour combinations against WCAG standards — giving you a clear starting point for building a more accessible palette. 

Try the Colour Contrast Checker here.