Stop 05 · Data VisualizationTopics · 10/10

Accessibility in Data Viz

In short

A sizeable share of people, especially men, have some colour vision deficiency, and some use screen readers. If your chart relies only on red vs green, part of your audience can't read it.

Making charts usable for colorblind viewers (via palette and pattern, not color alone) and screen-reader users (via alt text and data tables) — often skipped, increasingly expected.

The jaadu walks up a ramp beside stairs next to a friend in a wheelchair.

Think of it like this

The ramp beside the stairs

A building with only stairs works for most people. Add a ramp and it works for everyone, including someone in a wheelchair or with a heavy suitcase. Accessible charts are that ramp: small changes that let every reader get the message.

Watch it happen

Making a chart accessible

Safe colours

Add shapes

Contrast

Labels

Alt text

1/5Swap red-green for a colour-blind safe pair like blue and orange.

The big ideas

What you need to know

Never colour alone

Pair colour with shape, pattern, position or a text label so meaning survives without it.

Contrast matters

Light grey text on white is hard for many people. Aim for strong contrast, especially for small text.

Alt text states the point

'Line chart: sign-ups doubled from March to June.' Not just 'chart of sign-ups'.

Offer the data

A simple table alongside the chart helps screen reader users and anyone wanting exact numbers.

Save yourself the pain

Common mistakes

Oops

A traffic-light dashboard where red and green are the only difference.

Do this instead

Add icons or labels like 'Below target' and use a colour-blind safe palette.

Oops

Alt text that says 'image' or just repeats the title.

Do this instead

Describe the key takeaway in one or two sentences.

Your mission

Audit one of your charts

~20 min

Quick check

A line chart uses red for 'actual' and green for 'target'. What's the best fix?

Go deeper

1Add text labels or patterns to a chart so it doesn't rely on color alone.
2Write alt text for a chart as if describing it to someone who can't see it.
3Learn why relying solely on a red/green color contrast excludes many viewers.