Character Limits

Every social network enforces a maximum length for post text, and Buffer validates against that limit before a post is scheduled or published. This guide covers the limit for each network, how Buffer counts characters, and channel-specific nuances.

On most networks Buffer counts length in UTF-16 code units, not in the number of characters you see on screen. Most text counts one to one, but emoji and the bold and italic Unicode letters, commonly used for LinkedIn formatting, count as two units each. A post that looks well under the limit can still be rejected because of this.

Limit per network

The table below shows the character limit Buffer applies to the post text for each network. Where a network also supports a first comment, its separate limit is listed too.

Some networks limit other fields as well:

• Pinterest and YouTube titles: 100 characters
• Threads topics: 50 characters, and a topic cannot contain & or .
• TikTok comments: 150 characters

On Mastodon the limit comes from the server your channel is on, so read maxCharacters from the channel's MastodonMetadata rather than assuming 500. Buffer caps it at 20,000 however high the server sets it.

Attached images and videos do not use up any of your characters. The one exception is TikTok, where attaching a video lowers the limit as shown above.

How Buffer counts characters

On most networks Buffer measures text length in UTF-16 code units, the same value you get from string.length in JavaScript. This matters because one character as a reader sees it is not always one code unit:

Characters in the Basic Multilingual Plane (ordinary Latin letters, digits, punctuation, most accented Latin, and so on) are one code unit each. Characters outside that plane are encoded as a surrogate pair and count as two code units each. This includes most emoji and the mathematical alphanumeric letters (U+1D400 to U+1D7FF) that power bold and italic text on LinkedIn.

So the length Buffer validates is often higher than the number of glyphs you can count by eye.

Some networks add their own rules on top:

Unicode bold and italic formatting

Networks don't natively support rich text in the post body, so any bold or italic formatting in a post is really a substitution of mathematical alphanumeric symbols. For example, the bold H is not the letter H (U+0048) but 𝗛 (U+1D5DB). Each of these substitute letters lives outside the Basic Multilingual Plane, so almost everywhere it counts as two rather than one.

Styling therefore costs about half your allowance on every network except Bluesky, which counts graphemes and charges the same for a styled letter as a plain one. A post written entirely in bold letters reaches LinkedIn's 3,000 at roughly 1,500 visible characters, and a free X post's 280 at roughly 140. That is why a post that looks far short of the limit can still fail validation.

What happens when you exceed the character limit

Exceeding the character limit is a typed mutation error. The request returns HTTP 200 and the failure is reported in the mutation payload's message field (see Error Handling).

{
  "data": {
    "createPost": {
      "message": "LinkedIn posts cannot exceed 3000 characters."
    }
  }
}

The other fields report the same way, with their own wording: LinkedIn first comment cannot exceed 1250 characters., YouTube title cannot exceed 100 characters., etc.

Because the count is in code units, a message like the above can appear even when your text looks shorter than the stated number.

Next steps

• Posts & Scheduling: creating and scheduling posts
• Error Handling: typed mutation errors and error codes
• Rate Limits: request and query limits