Social media caption limits and hashtag rules, platform by platform

The post is scheduled for the evening. Someone pastes the approved caption from a document, the upload is refused, or it goes out and the hashtags quietly do nothing. Twenty minutes later, with the client or the boss waiting, the cause turns out to be a rule that could have been checked in seconds.

Most of these failures trace back to a short list of rules, and most of those rules change from one platform to the next. What follows sticks to limits the platforms state themselves. Advice about a perfect hashtag count, or blacklists of tags that no platform has ever released, is left out rather than dressed up as a rule.

How long a caption can be

• Instagram: 2,200 characters per caption.
• TikTok: 4,000 characters per caption.
• YouTube: 5,000 characters in a video description.
• LinkedIn: 3,000 characters per post.
• X: 280 characters per post, measured with a weighted count.
• Threads: 500 characters per post.
• Facebook: 63,206 characters per post.

The gap between those numbers is the real lesson. A full-length Instagram caption is far too long for X, and a LinkedIn post that uses its whole allowance will not fit on Threads. Instead of expecting one text to stretch across every network, write the long version once and then trim a version for each platform.

X keeps its own count

On X, not every character costs the same. Any link counts as 23 characters, however long or short the address. Letters from the Latin, Greek, Cyrillic, Arabic and Hebrew ranges count as one each. Most other characters, emoji among them, and Chinese, Japanese and Korean characters, count as two.

That trips people up in both directions. A post that looks comfortably short can be over the limit once a link takes its 23 characters. A caption sprinkled with emoji uses up the allowance at double the rate of the same words without them. For brands in the Gulf there is one piece of good news: Arabic is counted at the same rate as English.

Hashtag caps, and what happens when you pass them

Three of these platforms set a hashtag limit you need to know about, and each one reacts differently when you exceed it.

• Instagram: up to 30 hashtags. Use more than 30 and the post will not publish.
• YouTube: up to 60 hashtags. Go over 60 and YouTube ignores every hashtag on the video, not just the surplus. The first three appear above the title.
• Threads: one topic tag per post.

YouTube's penalty is the harshest, because it is all or nothing. Instagram's is the most noticeable, because the post simply fails. Neither limit is a target. Treat them as ceilings you have no reason to reach.

A hashtag repeated in the same caption still counts towards the limit while adding nothing, so remove duplicates. And since YouTube shows the first three tags above the title, put the three you care about most at the front.

Punctuation cuts a hashtag short

A hashtag carries on through letters, numbers and underscores, and ends at the first punctuation mark. A hyphen, an apostrophe or a full stop will stop it. Written as #self-care, the tag links only as #self. A tag with an apostrophe links only up to the letters before it.

It is among the commonest slips in brand captions, since the tag reads perfectly well in the draft. The usual fix is to run the words together, or to use an underscore where the platform accepts one.

Where a link in the caption goes nowhere

Links in posts can be clicked on YouTube, LinkedIn, X, Threads and Facebook. On Instagram and TikTok, a link typed into a caption appears as plain text. It cannot be tapped, and copying it out of the app is fiddly enough that hardly anyone bothers.

If a caption on those two platforms relies on a link, send people another way: to the link in bio, or to a link sticker in stories. Settle that while the caption is being written, not after the post has gone live with a dead address in the middle of it.

The part of the caption people actually see

In the Instagram feed, only about the first 125 characters appear before the rest is folded away behind "more". Anything beyond that point is read only by people already interested enough to tap.

So the opening line of an Instagram caption carries most of the weight. Put the hook there, and any call to action. A caption that starts with a greeting, a date or a row of hashtags has used its visible space on nothing.

Other platforms fold long captions too, but where the cut falls depends on the device and the layout, so there is no fixed number to quote. The principle still applies everywhere: write the first line as if most readers will stop there.

A platform's limit decides what it will accept. The fold decides what people will actually read, and that is the number worth writing for.

Check before approval, not after

Rules this simple feel safe to check by eye, which is exactly why they slip through. Run each caption through a check ahead of approval rather than after, so the version that is signed off is the version that publishes. Keeping captions, approvals and the posting schedule together in one place closes the last gap between the two.

Getting the timing right is the other part of a post that works. General guides to the best time to post are a reasonable starting point, but once an account has enough history, its own analytics will tell you more than any general chart.

If your team is producing captions in Arabic and English across several platforms and wants a simpler way to keep them within the rules, ALXO would be glad to hear how you work today and talk through the options.