Caption length has a real answer for each platform, and it fits in one table. The rule underneath the numbers: the words before the truncation point do almost all the work, because most people never tap "more".
Hard limits are the platform maximums. The cut-off is where the feed hides the rest. The sweet spot is what we see work across client accounts.
| Platform | Hard limit | Feed cuts off after | Sweet spot |
|---|---|---|---|
| 2,200 characters | ~125 characters | 70-125 characters for reach, 150-300 words for teaching posts | |
| TikTok | 4,000 characters | about one line | Under 100 characters, main keyword first |
| 63,206 characters | ~400-480 characters | Under 80 characters for engagement, 100-250 words for offers | |
| 3,000 characters | ~140 characters on mobile | 150-200 words, hook inside the first 140 characters |
TLDR: Write your first 125 characters as if they are the whole caption, because for most viewers they are. Go long only when the extra words carry steps, proof, or a story: Instagram carousels, Facebook offers, LinkedIn lessons.
Instagram caption length: 125 characters is the real limit
The hard cap is 2,200 characters, but the feed truncates around 125 characters behind a "more" link. That first block holds your hook, your keyword, and your ask.
Three ranges cover almost every Instagram post:
- 70-125 characters for reach plays: memes, quick tips, product shots. One line of benefit, one ask (save, comment, share).
- 150-300 words for carousels and teaching posts. Long captions earn saves when they add steps the slides skip. Front-load the promise, because nobody expands a caption that starts slow.
- Reels: one short line. The caption sits on top of the video and truncates to roughly a single line in the Reels feed. Keep it under 100 characters, keyword early, and put the rest of the context on-screen.
Instagram search reads captions, so name the topic plainly in the visible part. Hashtags: 3-5 focused ones, not 30.
TikTok caption length: short caption, searchable words
TikTok now allows 4,000 characters, which tempts people into essays. Skip the essay. The feed shows about one line, viewers are watching the video, and the caption's real job is search.
- Stay under 100 characters for most posts.
- Put the search phrase first: "easy meal prep for night shifts" beats "You NEED to try this".
- Long captions (300+ characters) have one use case: storytime and how-to posts where you want TikTok search to index details the video only says out loud. In our experience they help discovery on evergreen how-tos and do nothing for trend content.
So yes, long captions can work on TikTok, but as a search asset, not as reading material.
Facebook caption length: shortest wins, with one exception
Facebook's limit is famously 63,206 characters. The feed folds the post at roughly 400-480 characters behind "See more".
- Under 80 characters is the engagement zone for organic page posts: questions, updates, link intros. Short posts consistently out-engage long ones on most pages we run.
- 100-250 words for the exception: offers, event promos, and testimonial posts that need proof before the ask. Lead with the result ("Sarah booked 3 clients from one post"), then the details, then one link.
- Facebook Reels: treat like TikTok. One short line, since the caption overlays the video.
Groups tolerate longer, conversational posts. Pages punish them.
LinkedIn caption length: win the first 140 characters
LinkedIn caps posts at 3,000 characters and truncates around 210 characters on desktop and roughly 140 on mobile. That first sentence decides whether anyone taps "see more" at all. The tap is widely believed to help distribution too, though LinkedIn has never confirmed it, so treat the hook as the prize and any algorithm boost as a bonus.
- 150-200 words total is the sweet spot for lessons and frameworks: enough room for a hook, three tight points, and a closing question.
- The hook must fit in 140 characters and contain a number or a tension: "We cut a client's posting schedule in half. Engagement went up 40%."
- One line per paragraph. Dense blocks die on mobile.
The habit that beats every number here
All four cut-offs teach the same move: write the first line last, and write it for the cut. Draft the caption, then rewrite line one until it works standalone.
The annoying part when you run several accounts is checking how each platform actually treats your specific caption. That is what a per-platform post preview is for: Mydrop shows you how your caption will look on Instagram, TikTok, Facebook, and LinkedIn before you hit publish, so a weak first line gets caught in the draft, not in the feed.
Find your own sweet spots in two weeks
Platform averages are the starting grid, not the finish line. Your audience has its own numbers, and they take about two weeks to find:
- Pick one platform and one content type.
- Publish 3 short-caption posts and 3 long-caption posts of the same type, same visual quality.
- Compare saves, comments, and reach 72 hours after each post. Keep the winner as your default.
Run the test at consistent hours so length is the only variable: find your best posting times first, then test captions inside those windows.
If writing four platform-specific versions of every caption is your bottleneck, Mydrop's AI caption tools draft the variants from one core idea, and the content calendar lets you schedule the whole test batch in one sitting. Start free, run the two-week test, and the caption length numbers you end up with will be yours, not Buffer's.
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