PostEaseThe short answer
A caption has three jobs: a first line that earns the tap on “more”, a body that delivers what the post promised, and an ending that gives people something to do, such as answer, save or click. Write the first line last, make it the most specific true thing in the post, and cut every word before the point. Then shape the caption for the platform: a search phrase on TikTok, Pinterest and YouTube, a lesson on LinkedIn, a question on X, Threads and Bluesky.
Each platform sets a text limit and shows only the start of longer text. YouTube Help says the first lines of a description show before “Show more”, and LinkedIn cuts posts short with “see more”. What sits above that cut decides whether the rest is read.
Text limits by platform
The limits each platform states in its own documentation, as listed in the sources:
| Platform | Text limit | Write for |
|---|---|---|
| Caption up to 2,200 characters; up to 5 hashtags | A first line that earns “more”, then a save-worthy body | |
| TikTok | Caption up to 2,200 characters, counted in UTF-16 | Two or three search words a viewer would type |
| YouTube | Title up to 100 characters; description up to 5,000 | The search phrase early in the title; the first lines of the description |
| Post up to 3,000 characters, cut short with “see more” | A specific opening line and short paragraphs | |
| X | 280 characters; a link counts as 23 | One clear claim or question |
| Title up to 100 characters; description up to 800 | The subject first, in search words | |
| Threads | Up to 500 characters; 1 topic tag | A view or question in your own voice |
| Bluesky | 300 characters, counted as you see them | A point and a few specific tags for feeds |
The first line
The first line does what a video’s first second does: it decides whether anyone reads on. Lead with the result, the question, the mistake or the claim, not with “So excited to share” or a greeting. A first line a stranger understands in one second, and that is specific to this post, beats a clever one that needs the rest to make sense.
- Weak: “Some thoughts on pricing.” Stronger: “We raised prices 20% and kept every customer. Here is what changed first.”
- Weak: “New recipe today!” Stronger: “The 10-minute pasta I make every Tuesday.”
- Weak: “Big news coming.” Stronger: say the news.
The body
Deliver what the first line promised, quickly. Short paragraphs of one or two lines read on a phone. A list is easier to scan than a paragraph. Use the words your audience uses, which you can take from their comments and questions. Keep one idea per caption; a second idea is a second post.
The ending
End with one clear thing to do. A real question you want answered brings comments; “save this for later” suits a checklist; a link suits a post whose point continues elsewhere. Avoid bait such as “comment YES”, which Meta has demoted on Facebook since 2017. Then reply to the comments, especially in the first hours: on Threads, Buffer found accounts got about 42% more engagement on posts where they replied.
Words that help a post be found
On search-led platforms, the caption tells the platform who the post is for. TikTok says it uses captions, sounds and hashtags as information about a video. Pinterest shows Pins by topic, and YouTube titles and descriptions are read for search. Put the two or three words a person would type in the caption or title, on the image or in the video, and in the description. On X, Threads and Bluesky, tags matter less than the conversation, though Bluesky’s custom feeds often select posts by tag.
Write faster without sounding like a template
Speed comes from structure, not shortcuts. Keep a short bank of first lines that worked, write captions in one sitting for the week, and draft from the post’s single point rather than from a blank page. If you use a tool to draft, rewrite it in your own words and cut the filler; a caption that reads like everyone else’s loses the reason to read it.
Hashtags
Use few and specific. Instagram allows up to 5 per post; Threads allows one topic tag. A specific tag that names the subject (#sourdoughbaking) helps a post reach people searching for it; a broad one (#love) does little. On LinkedIn and X, two or three at most, and only where they name the topic.
Questions
How long should a social media caption be?
As long as the post needs, within the platform’s limit, with the point in the first line. Instagram and TikTok allow 2,200 characters, LinkedIn 3,000, X 280, Threads 500 and Bluesky 300.
What should the first line of a caption say?
The most specific true thing in the post: the result, the question, the mistake or the claim. It is what shows before “more”.
What is a call to action in a caption?
The one thing you ask the reader to do next: answer, save, share, click or book. Make it specific and give one per post.
Should every caption end with a question?
Only when you want answers. A checklist suits “save this”; a post that continues elsewhere suits a link. One clear ask per caption.
How many hashtags should I use?
Few and specific. Instagram allows up to 5 per post and Threads one topic tag; choose tags that name the subject.
Sources
- Meta, IG User Media, Instagram Platform reference, checked October 2026.
- Instagram, Use hashtags on Instagram, checked October 2026.
- TikTok, Content Posting API: direct post reference, checked October 2026.
- YouTube, Edit video settings, checked October 2026.
- LinkedIn, Differences between posting updates and publishing articles, checked October 2026.
- X, Counting characters, X API documentation, checked October 2026.
- Pinterest, Review Pin specs, checked October 2026.
- Meta, Threads Posts, Threads API documentation, checked October 2026.
- Bluesky, app.bsky.feed.post, app.bsky.embed.images and app.bsky.embed.video lexicons, checked October 2026.
- Buffer, Replying to your Threads comments can boost engagement by 42%, February 2026.
- TikTok, How TikTok recommends videos #ForYou, June 2020.
- Meta, Fighting engagement bait on Facebook, December 2017.