In a nutshell
Alt text is a description that tells people who can't see an image what the image conveys, in words. It is also called ALT. The screen readers on smartphones and computers read this text aloud in place of the image.
Limits by network
X's Help explains that image descriptions help people who are blind or have low vision, and people in areas with slow connections, and sets the limit at 1,000 characters (How to make images accessible for people, as of October 2026).
| Network | Characters you can add from SNS TOWN |
|---|---|
| X | 1,000 |
| Threads | 1,000 |
| 1,000 | |
| Facebook Pages | 1,000 |
| 200 |
Even though the limit is long, X's Help recommends keeping descriptions concise, because some assistive technologies used to cut off reading partway.
Tips for writing it
Don't start with "image" or "photo." Write what is shown and what the post wants to convey. For a photo of a new menu item, something like "A bowl of chicken and egg over rice with a soft-boiled egg on top, served in a white bowl" works; the standard is whether someone who can't see can still get the intent of the post. For announcements with text in the image (such as a change in opening days), write that text into the alt text too, because text inside an image isn't read aloud.
For a carousel with several images, add a description for each one. If food photos follow one another, write them so that the differences (portion, plating, seasonal ingredients) come across, and people listening by screen reader will understand why you lined them up. The effort of writing descriptions also builds the habit of asking, when you choose an image, "What does this one image say?"
How to make images is covered in How to make social media images, and how images and text share the work in How to write posts that get read.
In SNS TOWN
When you attach an image in the composer, a "+ALT" button appears for each image. Pressing it opens a field for the description, and you can enter up to the limit of the network selected in the header. The description you write is sent to each network along with the image when you publish. The steps are in Attaching images and videos.
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