Giới hạn ký tự này được mở rộng từ 140 ban đầu lên 280 ký tự vào năm 2017. The change aimed to give English-speaking users more room to express themselves, but the effective limit for CJK languages remained unchanged. X's character counting is not based on Unicode code points but on the Twitter Text library's proprietary weighting rules: half-width alphanumeric characters count as 0.5 each (out of 280), while CJK characters count as 1 each. X marketing strategy books teach effective post writing techniques.

Quy tắc đếm đặc biệt quan trọng cần hiểu. URLs count as 23 characters regardless of actual length (converted to t.co shortened URLs). Image and video attachments do not count toward the limit. @mentions count toward the limit, but auto-inserted @usernames at the beginning of replies do not. Emoji count as 1-2 characters depending on type, and skin-tone modified emoji or ZWJ sequences (combined emoji) count as multiple characters despite appearing as one.

X Premium (gói trả phí) cho phép bài đăng dài lên đến 25.000 ký tự, but only the first few lines appear in the timeline, requiring a "Show more" tap to read the full text. This makes it crucial to capture reader interest within the first 140 characters (for Japanese). From a marketing perspective, data suggests that posts completing within the free plan's 140-character limit achieve higher engagement rates.

So với các nền tảng tương tự, Threads allows 500 characters, Bluesky 300 characters, and Mastodon defaults to 500 characters (varies by instance). Understanding each platform's character limits and adjusting content for cross-posting is essential in social media management. SNS writing technique books explain effective expression within character limits.

Đối với công cụ đếm ký tự, hỗ trợ phương pháp đếm riêng của X là quan trọng. Since standard character counting and X-specific counting produce different results, a feature that shows remaining characters by X's standards before posting is practically valuable for users.