The maximum number of characters in a Twitter username is 15. A username, also called a handle, is the unique identifier that begins with “@” and appears in profile URLs, replies, mentions, and direct-message conversations.
The limit helped Twitter keep handles compact and readable in a service originally designed around short messages and mobile screens. Usernames can contain letters, numbers, and underscores, but they cannot include spaces. The “@” symbol identifies the handle but is not normally counted as part of the username’s character limit.
A frequent source of confusion is the difference between a username and a display name. The username is unique and capped at 15 characters, while the display name is the more flexible label shown beside it. Display names can include spaces and are intended for names, brands, or descriptive text.
The limit applies to ordinary current accounts, although platform documentation notes that some historical accounts may exist with longer usernames. For standard quiz purposes, 15 is the canonical answer.