Alt text
Alt text is a written alternative that communicates an image’s relevant information for people who cannot see it.
Definition
Alt text is a written alternative that communicates an image’s relevant information for people who cannot see it. It helps screen-reader users understand visual content and can also provide context when an image is unavailable. The description should serve the image’s purpose within the post.
For a chart, name the important comparison, values, and conclusion rather than only saying “bar chart.” For a screenshot of an error, include the relevant message. A decorative detail usually matters less than the evidence the image contributes to the explanation.
Alt text is distinct from a visible caption, although the two should complement one another. Avoid stuffing the description with promotional phrases or repeating surrounding copy without adding useful information. When adapting an image for another platform, check that the alternative description is present in the actual publishing interface. If an explanation is too complex for a concise description, provide the essential information in nearby text as well.
Example
For a bar chart, the alt text states that support requests fell from 120 in May to 80 in June.
How to apply it
Write alt text before you schedule, not in the publishing window. For a chart, include the comparison and the numbers, such as "support tickets fell from 120 in May to 80 in June." Stay near 125 characters if the composer warns you, and put extra detail in the visible caption. On X, Threads, and a Facebook Page, confirm the field is actually filled in the preview, because some tools drop it on retry.
If you cross-post, rewrite alt text rather than assuming it copied. A cropped carousel panel needs its own description. Decorative backgrounds can be described briefly or marked decorative if the platform allows it. When the image is the evidence, nearby text should still state the result so a failed image load does not hide the point. Recheck alt text when you swap an image 10 minutes before send.
Common mistakes
- Writing 'image' or 'chart' with no values, comparison, or conclusion.
- Stuffing the description with promotional phrases instead of what the image shows.
- Assuming a cross-post copied alt text when the second platform's preview is empty.
Related terms
Related reading
- Making Threads Accessible: Inclusive Content That Reaches Everyone
- Visual Storytelling: Enhancing Threads with Images and Graphics
Frequently asked questions
What is Alt text?
Alt text is a written alternative that communicates an image’s relevant information for people who cannot see it.
How do you use Alt text in a thread?
Write alt text before you schedule, not in the publishing window. For a chart, include the comparison and the numbers, such as "support tickets fell from 120 in May to 80 in June." Stay near 125 characters if the composer warns you, and put extra detail in the visible caption. On X, Threads, and a Facebook Page, confirm the field is actually filled in the preview, because some tools drop it on retry.
Example of Alt text
For a bar chart, the alt text states that support requests fell from 120 in May to 80 in June.