When a report user navigates to a visual, the screen reader will read out the title, visual type, and the alt text. Adding Alt Text (alternative text or textual alternative) allows screen readers (assistive technologies) to provide visually impaired readers with a better understanding of a document’s overall content.
Finding the best alt text is more of an art than a science. So, make sure you add alt text to every object that conveys meaningful information on a report. Providing alt text ensures that consumers of your report understand what you are trying to communicate with a visual, even if they cannot see the visual, image, shape, or textbox.
You can provide alt text for any object on a Power BI Desktop report by
- selecting the object (such as a visual, shape, and so on) and in the Visualizations pane
- select the Format section
- expand General
- scroll to the bottom
- fill in the Alt Text textbox. Please also note that the Alt Text textbox has a limit of 250 characters.
Conditional formatting for alt text
Since Power BI data is dynamic you can use DAX measures and conditional formatting to create dynamic alt text. Screen readers are then able to call out values specific to the data that a report consumer is viewing.