> ## Documentation Index
> Fetch the complete documentation index at: https://docs.letmepost.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# threads.media.alt_text_max_graphemes

> Threads alt text caps at 1000 graphemes per media item.

## What it checks

`countGraphemes(item.altText) <= 1000`.

## Why 1000

Meta's Threads API docs don't publish an explicit alt-text cap, so we use the nearest analogue we trust — half of Instagram's 2200-cap, sized down because Threads alt text is rendered in narrower contexts. The 1000 number is conservative: anything below it has been accepted upstream in our testing.

If Meta publishes an explicit cap that differs, this rule will follow.

## Failure response

```json theme={"system"}
{
  "error": {
    "code": "preflight_failed",
    "rule": "threads.media.alt_text_max_graphemes",
    "platform": "threads",
    "message": "Alt text is 1240 graphemes; Threads allows at most 1000."
  }
}
```

## Remediation

Tighten the description. Alt text should describe the image's content; if you have more to say, it belongs in the post body.

## Related

* [`bluesky.media.alt_text_max_graphemes`](/preflight/bluesky-media-alt_text_max_graphemes) — Bluesky caps at 2000.
* [`instagram.media.alt_text_max_graphemes`](/preflight/instagram-media-alt_text_max_graphemes) — IG caps at 2200.