How long a caption can be, per platform
From 250 characters to 63,206 — a factor of 253 between the tightest platform and the loosest.
The numbers
These are the ceilings the Contentbuilder app enforces, taken from its own source. The bars use a square-root scale so the short ones stay readable — on a linear scale Facebook's bar would be 253 times Snapchat's and the other five would be invisible.
- Snapchat 250
- X 280
- WhatsApp 700
- Instagram 2,200
- TikTok 4,000
- Facebook 63,206
A 300-character caption — three short sentences — is already too long for Snapchat and X. You find that out after you post.
Hashtags have their own ceiling, and it is not the same one
Hashtags are counted separately, and the sensible number differs far more than the character limit suggests. On one platform they do nothing at all.
| Platform | Caption characters | Hashtags |
|---|---|---|
| Snapchat | 250 | 3 |
| X | 280 | 3 |
| 700 | none — they are not links there | |
| 2,200 | 30 | |
| TikTok | 4,000 | 10 |
| 63,206 | 5 |
What happens when you go over
Not one thing, which is the annoying part. Depending on where you are, a long caption is rejected outright, silently truncated, or accepted and then collapsed behind a "more" link that most readers never open. The last one is the worst, because it looks like it worked.
Pasting fails differently too. A caption composed for a 4,000-character surface, pasted into a 280-character field, may simply refuse to paste, may paste the first 280 characters, or may paste everything and fail on submit — and you will be looking at a compose box, not at a helpful error.
Writing once for all six
- Put the point in the first 250 characters. That clears the tightest platform, and on every other one it is the part shown before "more" anyway. This is the whole technique.
- Write the rest as an extension, not as a middle. If the caption still reads correctly when the last two sentences are cut, a truncation is a shortening rather than a break.
- Keep hashtags out of the first line. They eat the characters that carry your point, and on the platform with a ceiling of none they are just noise.
- Count before you paste. Every compose box counts, but only after you are already in it, with the media attached and the moment gone.
Contentbuilder does the counting while you write, against whichever platform you have selected, and flags a caption over the limit before the hand-off rather than after. See it in the preview.