Alt text on TikTok: where it goes, and why your caption can’t do the job

You can add alt text to a TikTok photo post, and you do not have to do it in the moment. TikTok says creators can add alt text to photo posts during upload or after publishing, so a post that went out without it can still be fixed. The announcement does not name the menu, and apps move things around, so look in the options for your photo post rather than trusting a screenshot from a year ago.

The caption does not do this job. Your caption is written for everyone scrolling past: it sets a mood, asks a question, adds hashtags. Alt text is the description of the image itself, the thing a screen reader user hears where a sighted viewer sees the photo. The two can overlap, but one cannot replace the other. If the difference is fuzzy, alt text, captions, and descriptions are broken out side by side in an earlier post.

What to write when the caption already says something

Start from what the picture shows, then add whatever the viewer needs that the caption does not cover. The W3C’s guidance on informative images is to convey the meaning of the image, keep it brief, and not repeat the text next to it. On TikTok that last point is the one people miss: if your caption already names the dish, the alt text should describe the frame, not say the name again.

TikTok’s announcement does not state a length limit, so aim for a sentence or two. Put the important part first, since that is what a listener hears before they decide to keep going. For what that listening experience is like, see how screen readers announce images.

Photo posts that are a set of images

If your post is a series of photos, each one needs its own description, and they should read in order. A slide that only makes sense after the previous one should say so. We cover that in describing a sequence of images.

Video is a different job

TikTok’s alt text announcement is about photo posts. For video, the same page points to auto-generated captions, which is a separate feature doing a separate job. If you use a still as a cover or a thumbnail, the thinking is closer to alt text for short video thumbnails. And when an image is purely decorative, the W3C’s images tutorial advises an empty text alternative, so there is nothing to read aloud.

TikTok has also said it is testing AI-generated alt text for screen readers. That is a test, not a feature you can plan around, and a generated description cannot know why you chose the shot. Write your own, and treat anything automatic as a fallback.

When you are clearing a stack of photo posts, take a screenshot of the image, run SnipAlt with Ctrl+Shift+A (⌘⇧A on a Mac), edit the draft, and paste it into the post.