Accessible presentations: slides for everyone

Accessible presentations help people with visual impairments who enlarge slides or have them read aloud, people with colour vision deficiency, people with hearing impairments who rely on captions and people with learning or concentration difficulties who benefit from clear structure.

But they help everyone else too: the audience in the back row, people viewing slides on a phone and anyone listening in a foreign language. Accessibility is above all good design.

Text must stand out clearly from the background. At level AA, WCAG requires a contrast ratio of at least 4.5 to 1 for normal text and 3 to 1 for large text. Light grey on white, text over busy photos or coloured type on a coloured background often fall short.

Use a legible sans-serif typeface at a sufficient size, avoid all capitals and justified text with large gaps. Colour must never be the only distinguishing feature. If red means loss and green means gain in a chart, add labels or patterns, because many people find red and green hard to tell apart.

Every image that carries information needs a text alternative that conveys that information. For a chart, that means not “bar chart” but the message, such as “Revenue abroad grew twice as fast as at home”. Purely decorative images are marked as decorative so that screen readers skip them.

Screen readers read slide elements in a defined order. This order does not always match the visible layout. Check it: the headline should come first, then the content in a sensible sequence. Use the placeholders of the slide layouts for title and content rather than stacking free text boxes; that helps the structure.

If a presentation is narrated or distributed as a video, it needs captions. For live talks, live captions or a transcript afterwards can help. Videos embedded in slides also need captions and, if important information is only in the picture, a description.

Avoid flashing or rapidly flickering elements; they can trigger seizures in some people. Animations should be calm and serve a purpose, such as revealing content in time with the explanation.

Accessibility concerns not just the file but the talk itself. Describe what can be seen on important slides as you speak, especially charts and images: people who cannot see well or at all can then follow the message without seeing the slide. Don’t just say “as you can see here”; say what there is to see.

Speak clearly and not too fast, face the audience while speaking so that people who lip-read can see your face, and share the slides in advance. Anyone who can open the slides on their own device beforehand can enlarge them or have them read aloud. At events with sign language interpreters, the interpreter should be clearly visible and well lit and receive the slides beforehand.

These points cover the most common barriers.

In Universe, explainer graphics are created as text rather than pixels, so their labels can be translated. Narrated courses have captions that are switched on at the speaker bubble, and the slide text size can be changed in the player. To be honest: contrast, focus order and screen reader behaviour on the platform have not yet been tested by a person; the statically checkable rules show no findings.