How long is your caption, really?

Three counters, three answers, and only one of them is the number you meant.

The same caption, three different lengths

Paste 👨‍👩‍👧‍👦 into three different character counters and you can get 1, 7 or 11. All three are correct, and they are answering different questions.

• One — what a reader sees. One picture of a family. This is what people mean by “a character”.
• Seven — the code points underneath. Four people and three invisible joiners holding them together.
• Eleven — the UTF-16 units the text occupies in memory, which is what text.length returns in JavaScript.

Almost every counter on the web reports eleven, because text.length is the obvious thing to write and it is correct for plain English. It is wrong for emoji, wrong for flags, wrong for skin-tone modifiers and wrong for many scripts. On an emoji-heavy caption the gap is not academic: it will tell you that you are over a limit you are nowhere near.

Which number the platform uses

Unhelpfully, this varies, so a limit is only meaningful when you know the unit it is counted in.

Most platforms count something close to what a reader sees. X is the notable exception and is worth knowing about in detail: every link costs a flat 23 characters however long it is, because links are rewritten to a fixed-length address, and characters outside the Latin range — including most emoji and all CJK — count as two.

That last rule surprises people writing in Japanese, Chinese or Korean: a 280-character limit is effectively 140 characters.

The cut-off matters more than the limit

Almost nobody hits a caption limit. Almost everybody hits the truncation point — the place where the feed collapses the caption behind “more”.

That point is much earlier than the limit and it is what actually decides whether your caption is read. Instagram shows roughly 125 characters, TikTok about 100, LinkedIn around 210 before it collapses to three lines, and a YouTube description shows two or three lines above “Show more”.

So the first sentence is doing nearly all the work. If it needs the second sentence to make sense, most people will never see it. Front-load anything that has to be read: the offer, the question, the reason to stop scrolling. Put the hashtags at the end where they belong, not in the middle of the part that shows.

Characters that survive the paste and break the post

Write a caption in a word processor, paste it into a post, and you bring things you cannot see.

Zero-width spaces are the classic. They have no width, they appear from web pages and some keyboards, and inside a URL one will stop the link working entirely. Inside a hashtag it splits the tag in two silently. There is nothing to see, so the cause is close to impossible to find by looking — people usually conclude the platform is broken.

Non-breaking spaces look exactly like ordinary spaces and behave differently in search and in exact matching. A handle or a code with one in it will not match the same text typed normally.

Curly quotes and en dashes are not faults at all — they are good typography and a caption is the right place for them. They only matter when something has to match exactly, such as a discount code or a URL.

Two that are worse than untidy

Bidirectional overrides reorder how text is displayed. What you read is not the order the characters are actually in. This is the mechanism behind filenames that appear to end in .txt while being something else entirely, and it works just as well in a caption or a bio.

Confusables are letters from other alphabets that render identically to Latin ones. The Cyrillic а is indistinguishable from the Latin a at any size, in any font. A link that reads as a familiar domain can contain one and point somewhere else completely. If you copied a URL from anywhere you did not type yourself, this is worth checking before you publish it to an audience.

Neither of these can be repaired automatically. Substituting a Latin letter for a Cyrillic one would rewrite the address, and the corrected version still would not be the address it appears to be. The only safe fix is to retype it.

Alt text, briefly

Alt text is read aloud to anyone using a screen reader. A few things go wrong often enough to be worth checking mechanically: starting with “image of” (the reader already says it is an image, so it is announced twice), pasting the filename, repeating the caption word for word, and running past about 250 characters, where some readers cut it off.

What no tool can check is whether it describes the actual picture. Say what is in the frame and why it is there, in a sentence.

Frequently asked questions

Why does this say my caption is shorter than another tool does?

Because most tools count in UTF-16 units, where a single emoji can be eleven characters. This counts what a reader sees and shows the other figures alongside, so you can see where the difference comes from.

What is the truncation point?

Where the feed collapses your caption behind a “more” link. It is far earlier than the character limit — around 125 characters on Instagram and about 100 on TikTok — and it is what decides whether your caption gets read at all.

Why does a long link only cost 23 characters on X?

Links there are rewritten to a fixed-length address, so every link costs the same regardless of its real length.

How does a zero-width space get into my caption?

Usually by copying from a web page, a word processor or a note-taking app. Some keyboards insert them too. They are invisible by definition, so nothing looks wrong until a link stops working.

Should I remove curly quotes?

Not for a caption — they are correct typography and look better. Straighten them only where an exact match matters, such as a discount code, a URL or a handle.

Is my caption uploaded anywhere?

No. Everything runs in your browser. Nothing is sent, stored or logged.