Alt text (alternative text) helps screen readers and other assistive software to interpret graphic elements within a text, such as photos, diagrams, icons and charts.
Without alt text, people with a vision impairment who are reading a text will not know what these elements are conveying. For example, a screen reader might just read out a photo’s dimensions rather than give any meaningful information on what it depicts.
This section outlines the key elements for placing alt text in a document so that all of your readers can access the content.
If your document is for a public audience, always use some alt text with photos, logos, icons, illustrations, charts or other graphics. This will mean readers with vision impairment can access that content, as screen readers will read the alt text that explains a graphic element.
At a minimum, write a title that describes the graphic element. If it would be helpful, make it a short description.
Effective alt text is about striking a balance between being meaningful and concise.
As a guide, keep your alt text around 125 characters. Otherwise, you risk frustrating readers because some assistive software has a limit and will simply cut it off mid-stream.
If you can, take any images that only include text and convert them to standard text so they are accessible to all readers.
If you are using a text-based logo, add the organisation or product name in the alt text. You don’t need to describe the logo design.