Content4 min read
How to Post on X and Threads: Limits, Threads, Cards
How to post on X and Threads properly: the real character limits, how a thread should be structured, and why your link card shows the wrong image.
Posting well on X and Threads is mostly mechanics: knowing where the character limit actually bites, structuring a thread so people read past the first post, and making sure a shared link renders the card you intended. None of it is difficult, and all of it is routinely got wrong.
How to post on X: the limits that matter
X counts characters in a weighted way rather than one-per-character. URLs are counted as a fixed length regardless of how long they are, and characters in scripts such as Japanese or Chinese count as two.
Threads has its own limit — 500 characters — and overflows into a chained post rather than refusing the text. X documents its own counting rules, including the URL weighting, in its developer documentation.
FreeMentioned in this article
Social Media Character CounterOne box, every platform’s limit, and exactly where each one cuts you off.The counter handles the weighting for both, alongside every other platform, which is more reliable than counting in a text editor. Detail: the Twitter character limit and the Threads character limit.
Threads that get read
A thread is a sequence, and the failure is nearly always structural rather than literary:
- The first post is the entire pitch. It has to work alone, because most people will
see nothing else. No "a thread 🧵" as the whole opening.
- One idea per post. A post crammed with three points is skimmed and abandoned.
- The second post carries the cost of the first. This is where the drop-off is.
- End with the point, not with a plug. A thread that ends by selling something
teaches people not to read the next one.
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X Thread SplitterTurn long writing into a thread that breaks in the right places.The splitter breaks long writing at sentence boundaries rather than mid-clause, which is the difference between a thread that reads naturally and one that is obviously an article chopped up. See how to write a Twitter thread.
Link cards come from the page
Post a URL and the card is built from that page's Open Graph and card tags — not from anything you attach. So a wrong card is a page problem, and the fix is on your site.
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Link Preview DebuggerWhat X, Facebook and LinkedIn will show when you share your link.The debugger fetches once and draws the card as X, Facebook, LinkedIn and chat apps each render it. See Open Graph tags and, when the card is stale or missing, link preview not showing.
Images and the timeline crop
X shows an attached image cropped to a band in the timeline and expands it on tap, so a tall image or a screenshot of text is reduced to something unreadable at the moment it matters.
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Social Image ResizerOne image, cropped to every size the networks actually use.Sizes and the crop behaviour are in Twitter image sizes for X. If you are sharing a post as an image, do it honestly — a drawn card proves nothing about who wrote it:
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Post Screenshot GeneratorA clean card of a post, drawn instead of screenshotted.Threads is not X with a different logo
Two differences that change how you write:
The limit is lower — 500 characters, with overflow chaining. That makes Threads closer to a short post format than a microblog.
Replies are the currency. Threads surfaces conversation, so a post that invites a reply outperforms one that states a conclusion. The profile people see when they arrive from a reply is worth more attention than on X — Threads bio ideas.
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Threads Post PreviewYour Threads post as the feed draws it, collapse and all.What travels on each platform
The mechanics above are necessary and not sufficient. What actually gets read differs between the two in a way worth naming.
On X, the unit that travels is a claim - something specific enough to be agreed with or argued against. Posts that state a position, share a number or make a comparison get quoted; posts that describe a feeling get liked and forgotten. The quote-post mechanic is the distribution engine, and you can only quote something that says something.
On Threads, the unit that travels is a prompt. The system surfaces conversation, so a post that invites a reply outperforms one that closes the subject. That is not a lower-quality bar, it is a different one: the question has to be worth answering, and "thoughts?" is not.
The practical version: write the claim first, then decide whether to end it with a full stop for X or a question for Threads. Same substance, different close.
Crossposting, carefully
The same text rarely works on both. A 280-character post reads as clipped on Threads; a 500-character Threads post does not fit on X at all. If you are publishing to both, write for the tighter limit and let the looser one carry it — and check both before publishing rather than after.
What is the character limit on X?
The standard limit is 280 characters for most accounts, counted with weighting - URLs count as a fixed length and some scripts count double.
How long can a Threads post be?
500 characters. Longer text chains into a second post rather than being rejected.
Why is my link preview showing the wrong image?
The card is built from the linked page's Open Graph tags and cached. Fix the page, then check what the platforms are actually reading.
Should I post the same thing on X and Threads?
Rarely word for word. The limits and the conversational norms differ enough that a post optimised for one reads badly on the other.
Check the limits, the weighting and the fold before you post: character counter.
Put it to work
Tools for the job you just read about
Free to run, most of them without an account.
FreeContent
Social Media Character Counter
One box, every platform’s limit, and exactly where each one cuts you off.
Count characters →
FreeContent
X Thread Splitter
Turn long writing into a thread that breaks in the right places.
Split →
FreePreviews
Link Preview Debugger
What X, Facebook and LinkedIn will show when you share your link.
Preview the URL →11 runs
FreeImages & video
Social Image Resizer
One image, cropped to every size the networks actually use.
Resize →
FreeImages & video
Post Screenshot Generator
A clean card of a post, drawn instead of screenshotted.
Generate →1 runs
FreePreviews
Threads Post Preview
Your Threads post as the feed draws it, collapse and all.
Preview →2 runs
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