blueskygrapheme clusters
Bluesky post limits and media specs
Every number below is the one our publishing engine enforces before a Bluesky post goes out, with the source it came from and the date we last read it.
Text[text]
| Max length | 300 grapheme clusters |
|---|---|
| Counting | Counted in grapheme clusters: a flag or a skin-tone emoji is one character however many code points it is built from. |
Media
| Constraint | Images[image] | Video |
|---|---|---|
| Per post | 4 | 1 |
| Formats | .png, .jpg, .jpeg, .webp | .mp4 |
| Max size | 1,000,000 bytes | 100 MB |
| Max length | - | 3 min |
| We publish it | yes | not yet |
We publish text and images here; video and PDF documents we do not deliver to Bluesky yet. One post carries images or a video, never both. A PDF deck degrades here into up to 4 slide images.
Mentions
A plain @handle.domain renders as text; linked mentions need facet metadata we do not build yet - prefer naming without @.
The guidance our own agent carries for Bluesky, verbatim.
How our publisher handles it
The notes our publishing engine carries for Bluesky, verbatim - what our adapter does, not only what the platform allows.
- The lexicon also caps posts at 3,000 bytes - heavy emoji use hits it before 300 graphemes.
Questions
- How long can a Bluesky post be?
- 300 characters. Counted in grapheme clusters: a flag or a skin-tone emoji is one character however many code points it is built from.
- How many images can one Bluesky post have?
- Up to 4: .png, .jpg, .jpeg, .webp, up to 1,000,000 bytes each.
- What video does Bluesky accept?
- 1 video per post: .mp4, up to 100 MB each, up to 3 min.
- How do you tag an account on Bluesky?
- A plain @handle.domain renders as text; linked mentions need facet metadata we do not build yet - prefer naming without @.
Sources, verified 2026-07-14
Each citation names where the number came from. Anything we could not confirm in an official document is marked, because a number nobody will stand behind should look different from one that is.
- [text]lexicon app.bsky.feed.post maxGraphemes 300 / maxLength 3000 bytesverified 2026-07-14
- [image]docs.bsky.app 4 images, 1,000,000 bytes eachdocs.bsky.appverified 2026-07-14