1.4.1 Use of Colour

Around 1 in 12 men and 1 in 200 women have some form of colour vision deficiency. Using colour alone to convey meaning excludes all of them. It also excludes people using high-contrast displays, monochrome screens, or printed materials.

This does not mean you cannot use colour. It means colour must always be paired with another visual cue such as text, pattern, shape, or icon.

For error states, do not use a red border alone. Also add an error icon or the word Error in the message.

For links within body text, do not rely solely on colour to distinguish them from surrounding text. Underline links, or use a different font weight alongside the colour.

For graphs and charts, do not use colour alone to differentiate data sets. Add patterns, labels, or different line styles.

For required form fields, do not mark them only with a red asterisk. Include the word Required in the label.

• Form validation that turns field borders red on error with no other indication
• Links within text that are a different colour but not underlined or otherwise distinguished
• Pie chart where slices are only differentiated by colour with no labels or patterns
• Status indicators that use only colour (green for active, red for inactive)

This criterion is about conveying information, not about colour choice in general. A decorative border that changes colour on hover does not convey information, so it does not need a non-colour alternative. A status badge that is green or red does convey information and does need one.