What each channel accepts
Every network has its own rules about caption length and media, and they don’t agree with each other. PostPost.ai knows them, checks your post against each channel before it sends, and tells you what it had to leave out.
The limits, per channel#
| Channel | Caption | Photos / videos in one post | Videos | Text-only post |
|---|---|---|---|---|
| 2,200 | up to 10, photos and videos mixed | up to 10 | no — needs media | |
| 63,206 | up to 10 | 1 | yes | |
| X | 280 (25,000 on X Premium) | up to 4 | 1 | yes |
| 3,000 | up to 9 | 1 | yes | |
| Threads | 500 | up to 10 | 1 | yes |
| TikTok | 2,200 | video only | 1 | no |
| YouTube | 5,000 | video only | 1 | no |
| Telegram | 4,096 (1,024 with media) | up to 10, photos and videos mixed | up to 10 | yes |
| Google Business Profile | 1,500 | 1 photo | none — no video | photo recommended |
Two rows worth reading twice:
- Telegram counts captions twice over. A plain message can be 4,096 characters; the caption under a photo or video is capped at 1,024 by Telegram itself.
- Google Business Profile takes one photo and no video at all. A carousel or a multi-photo post still goes there — as its first image, with the rest reported as left out.
Only Instagram and Telegram put photos and videos in the same post. Everywhere else a mixed set is split down to what that network can carry.
When your post is bigger than a channel’s limits#
PostPost.ai publishes what fits and tells you what didn’t, per channel — it does not refuse the whole post because one network is fussier than the others:
- Too many items → the channel gets as many as it takes (X gets 4 slides of a 6-slide carousel) and the post records “posted 4 of 6 items”.
- A file that channel can’t take → it’s dropped from that channel’s send only. Instagram, for example, publishes JPEG and PNG photos and wants an aspect ratio between 0.75:1 and 1.91:1, so a GIF or an extreme panorama goes to your other channels and not to Instagram.
- Nothing left to send → only then does that one channel report a failure. Your other channels still publish on time.
Captions that are too long#
If a caption is over a channel’s limit you’ll see it before the post goes out, with a Shorten action that rewrites just that channel’s copy. The one exception is X: its limit depends on a subscription we can’t see from here, and X counts characters its own way (every link counts as 23), so PostPost.ai warns and lets X decide instead of blocking a post your account may be able to publish.
Which formats each channel takes#
Not every channel takes every format — Google Business Profile has no stories, TikTok and YouTube take video only, stories are Instagram and Facebook. The table in Creating posts and carousels with AI has the full mapping, and the composer only offers you the channels that can actually carry what you’re making.