Character Limits for Social Media, Forms, and the Web

Text messages (SMS)

A single SMS holds 160 characters when every character is in the basic GSM-7 alphabet (standard Latin letters, digits, and common punctuation). As soon as the message contains a character outside that alphabet — an emoji, many accented letters, or a non-Latin script — the whole message switches to UCS-2 encoding and the limit drops to 70 characters.

Longer messages are split into segments that phones reassemble. Each segment gives up a few characters to reassembly information, so segments hold 153 GSM-7 characters or 67 UCS-2 characters. If you send messages through a paid service that bills per segment, one emoji can change the cost of a long message.

Posts on X

X’s developer documentation says standard posts can contain up to 280 characters, but not every character weighs the same. Every URL counts as 23 characters regardless of its real length, because links are wrapped in X’s t.co shortener. Every emoji counts as 2 characters, and Chinese, Japanese, and Korean characters count as 2 each.

That means a plain character count will usually be close for Latin-script text without links, but can be well off for posts with URLs, emoji, or CJK text. Paid tiers can allow longer posts; the 280 figure applies to standard posts.

Search result snippets and page titles

Google’s documentation states there is no limit on how long a meta description can be, but the snippet is truncated as needed, typically to fit the device width. Truncation is based on display width, not a fixed character count, so a line of wide letters is cut sooner than a line of narrow ones.

Treat commonly quoted character targets for descriptions and titles as rough guides. Put the most important words first, so that whatever gets cut is the least important part.

Web forms and database fields

A form field’s maximum length is set by the site that built it. In a browser, the standard HTML maxlength limit is measured in UTF-16 code units rather than visible characters, which is why a field can fill up faster when you type emoji: most emoji use two code units, and combined emoji use more.

Behind the form, databases may limit bytes instead of characters, where an accented letter or an emoji takes more space than a plain letter. And when a form is submitted, each line break is sent as two characters. If a site rejects text that looked short enough, one of these differences is usually the cause.

Writing to a limit

1. Draft freely first, then cut; trimming a complete thought is easier than writing a squeezed one.
2. Delete words that repeat the context (“in order to” → “to”, “at this point in time” → “now”).
3. Prefer one precise word over a phrase, and active verbs over nouns (“decide” instead of “make a decision”).
4. Move secondary details to a link, a reply, or a follow-up message.
5. Check against the platform itself before sending — its own counter applies its own rules.