Twitter originally restricted users to 140 characters per post. The limit came from Twitter’s early design around mobile-phone text messaging, or SMS, which traditionally allowed messages of up to 160 characters.
Twitter reserved 20 characters for a username, leaving 140 characters for the message itself. That constraint helped shape the platform’s distinctive style: abbreviated words, hashtags, concise updates, and links shared through URL-shortening services. What began as a technical limitation became one of Twitter’s defining cultural features.
The limit was gradually loosened before being removed in practice. In 2016, media attachments and some usernames stopped counting toward the limit. In November 2017, Twitter doubled the standard limit to 280 characters, although the company retained the original brevity-focused identity. The service was later rebranded as X, and some paid users received much larger limits. A common mix-up is saying Twitter always used 280 characters; 140 was the original limit and remained in place for more than a decade.