Caption rules are the kind of detail that nobody thinks about until a post fails. A caption is pasted from a document into the scheduler, the upload is refused or the hashtags quietly stop working, and somebody spends twenty minutes working out why while the client waits.
Most of these problems come from a small set of rules, and most of them differ by platform. This is the set the free caption and hashtag checker on this site applies. It only enforces limits the platforms state themselves. Advice about a magic number of hashtags, or lists of banned tags that no platform publishes, is left out rather than presented as a rule.
Character limits, platform by platform
These are the maximum lengths the checker counts against. It counts one character per visible character, so an emoji counts as one, except on X, which is covered below.
- Instagram: 2,200 characters in a caption.
- TikTok: 4,000 characters in a caption.
- YouTube: 5,000 characters in a description.
- LinkedIn: 3,000 characters in a post.
- X: 280 characters in a post, counted in a weighted way.
- Threads: 500 characters in a post.
- Facebook: 63,206 characters in a post.
The practical lesson is that a single caption rarely fits everywhere. A long Instagram caption is well over the limit on X, and a LinkedIn post written to its full length will not fit on Threads. Write the long version once, then cut it for each platform, rather than hoping one text will stretch.
Why X counts differently
X does not count every character the same way. The checker follows its weighting: every link counts as 23 characters however long it is, letters in the Latin, Greek, Cyrillic, Arabic and Hebrew ranges count as one, and most other characters, including emoji and Chinese, Japanese and Korean characters, count as two.
This catches people in both directions. A short link still costs 23 characters, so a post that looks well under the limit can be over it. And a caption full of emoji uses the allowance twice as fast as the same caption in plain text. For Gulf brands, Arabic text counts at the same rate as English, which is one less thing to worry about.
Hashtag limits
Only three of the seven platforms have a hashtag limit the checker enforces, and each one behaves differently when you go over.
- Instagram allows 30 hashtags. With more than 30, the post will not publish.
- YouTube allows 60 hashtags. Over 60, YouTube ignores every hashtag on the video, not just the extra ones. The first three show above the title.
- Threads takes one topic tag per post.
The YouTube rule is the harshest, because the penalty is total. The Instagram rule is the most visible, because the post simply fails. Neither is a reason to use the full allowance. They are ceilings, not targets.
Repeated hashtags count towards the limit and add nothing, so the checker flags them. On YouTube, where the first three hashtags are shown above the title, the order is worth choosing deliberately.
Hashtags that break early
A hashtag runs through letters, numbers and underscores, and stops at the first punctuation mark. A hyphen, an apostrophe or a full stop ends it. So #self-care links as #self, and a tag written with an apostrophe links only as far as the letters before it.
This is one of the most common mistakes in brand captions, because the tag looks right in the document. The checker lists any hashtag that will break and shows what it will actually link as. The fix is usually to join the words, or to use an underscore where the platform allows it.
Links that will not click
Links are clickable in posts on YouTube, LinkedIn, X, Threads and Facebook. On Instagram and TikTok, a link in a caption shows as plain text. Nobody can tap it, and copying it from the app is awkward enough that almost nobody does.
If a caption depends on a link, it needs a different route on those two platforms: point people to the link in bio, or use a link sticker in stories. Better to decide that when the caption is written than to discover it after the post is live with a dead URL in the middle of it.
Where captions get cut off
On Instagram, only about the first 125 characters show in the feed before the caption is folded behind "more". Everything after that is read only by people who were already interested enough to tap. The checker shows exactly where that cut falls on your caption.
That makes the opening line the most important part of an Instagram caption. Put the hook and any call to action in it. A caption that opens with a greeting, a date or a string of hashtags has spent its visible space on nothing.
The other platforms fold long text too, but where they do it varies with the device and the layout, so the checker does not claim a fixed number for them. The same principle holds: write the first line as if it is the only one most people will read.
The limit tells you what the platform will accept. The fold tells you what people will actually read. The second number is the one that matters for the client.
Build the check into the process
These rules are simple enough that checking them by eye seems reasonable, and that is exactly why they get missed. Run the caption through a check before it goes to the client for approval, not after, so the version they sign off is the version that will publish.
Timing is the other half of a post that works. The best time to post tool on this site suggests windows for each Gulf country, built from time zones, the working week and how Ramadan moves the day, and says plainly that an account's own analytics beat any general chart once there is enough history. Inside Wiro, captions, approvals and the schedule sit on the same calendar, so the checked caption is the one that goes out.
