Caption and media limits per platform
Captions: X 280 characters, Threads 500, Bluesky 300, Instagram and TikTok 2,200, LinkedIn 3,000, YouTube descriptions 5,000, Facebook 8,000. Video in the web composer is currently accepted up to 3 minutes and 4 GB. Instagram Reels must be 3 to 90 seconds through the API. Recommended export: MP4, H.264 video, AAC audio.
Last checked September 24, 2026
Caption limits the composer enforces
| Platform | Characters |
|---|---|
| 2,200 | |
| TikTok | 2,200 |
| YouTube | 5,000 |
| 8,000 | |
| X | 280 |
| 3,000 | |
| Threads | 500 |
| Bluesky | 300 (counted per character as Bluesky counts them) |
- Instagram counts hashtags separately: 30 is the maximum, and going over reads as "caption too long".
- Threads allows up to 5 links in a post.
- When a caption is over a platform’s limit, the composer flags that platform and lets you shorten the caption for it alone.
Video and images
- Web composer video cap today: 3 minutes and 4 GB per file. Longer videos are on the roadmap for the platforms that allow them.
- Instagram Reels: 3 to 90 seconds, 9:16 or 1:1, MP4 (H.264). Instagram rejects other codecs and unusual aspect ratios.
- Bluesky video: up to 10 minutes and 300 MB; images up to 1 MB each.
- TikTok: one video per post, 9:16 recommended. Photo carousels are supported.
- YouTube: video only, with a title. Shorts are vertical videos; the same upload works for long-form when it is landscape.
- HEIC and WebP images are converted before publishing so every platform gets a JPEG it accepts.
Related
Something here wrong or missing? Email support@socialync.io.