Colour and Accessibility: Designing for Everyone

Colour does a lot for a website: it carries your brand, sets a mood and guides the eye. But colour decisions are also accessibility decisions, because the wrong combinations make text hard or impossible to read for a meaningful number of people.

A significant share of visitors have some form of colour vision deficiency, and many more simply have ageing eyes or are reading in bright sunlight. Designing with that in mind helps everyone. This guide explains how.

Contrast is the foundation

The single most important rule is enough contrast between text and its background. Pale grey text on white, or text laid over a busy image, looks elegant in a mockup but becomes a struggle to read in the real world, especially on phones outdoors.

There are recognised contrast guidelines, and free tools let you check any text-and-background pairing against them in seconds. Aiming to meet those standards is a simple, objective way to make sure your content is readable by as many people as possible.

Do not rely on colour alone

Some visitors cannot reliably tell certain colours apart, so colour must never be the only way you convey meaning. A form field shown as wrong using red alone leaves colour-blind users guessing; add an icon and a text message and everyone understands.

The same goes for links, charts and status indicators. Pair colour with an underline, a label, a pattern or a symbol. The colour can still be there for everyone else; you are simply making sure no one is excluded.

Use a restrained, purposeful palette

A tight palette is easier to make accessible and looks more professional. Choose a small set of colours, decide what each is for, and reserve one strong colour for actions so buttons stand out consistently. Too many competing colours both confuse and complicate accessibility.

Test your choices in real conditions: on a phone, in bright light, and ideally with a colour-blindness simulator. What looks fine on a designer’s calibrated monitor can be a different story on a cheap screen in a sunny car park, which is where many of your visitors actually are.