Captions help Deaf and hard-of-hearing viewers, and the many people who scroll on mute. Alt text lets screen-reader users "see" your images. Both take seconds.

Instagram

  • Auto captions on Reels: Add the Captions sticker in the editor, wait for it to transcribe, fix any wrong words, then pick a style.
  • Captions on an existing post: Open the ••• menu → Edit → Advanced settings, then toggle captions on or off.
  • Viewers can turn on captions under Settings → Accessibility → Captions.
  • Alt text for photos: Before sharing, go to Advanced settings → Accessibility → Write alt text. You can also add it later by editing the post.
  • Meta's API allows alt text of up to 1,000 characters, for image posts only.
  • If your video already has burned-in subtitles, turn auto captions off so they don't overlap.

TikTok

  • Auto captions: Turn them on from the editing screen before posting, then edit any mistakes.
  • Alt text on photo posts: Add it during upload or after posting (launched April 2025).
  • TikTok is also testing AI-generated alt text.
  • Manage the options from TikTok's Accessibility settings page.

Writing good alt text

  • Describe what matters: "Woman in a yellow raincoat pouring coffee at a Lisbon café counter."
  • Skip "image of…".
  • Include any text that's in the image.
  • 1–2 sentences is plenty.