Halfwidth and fullwidth forms
lastmod 2025-02-06created 2024-07-204 edits
In East Asian typography there are the concepts of fullwidth (全角, jeongak) and halfwidth (半角, bangak).
Fullwidth characters (全角文字) and halfwidth characters (半角文字) are terms used mainly in the printing cultures of China, Japan and Korea. A character whose width is about twice the fixed width of an ordinary Latin letter is called a fullwidth character, and correspondingly a character whose width is half that of a fullwidth character is called a halfwidth character. In Western typography, the term em is somewhat similar to the concept of fullwidth. Hangul and Chinese characters mainly fall into the fullwidth category, while Latin letters and the like fall into the halfwidth category. In addition, the characters in ASCII also have fullwidth counterparts.
On computers, halfwidth characters were traditionally often encoded in 1 byte and fullwidth characters in 2 bytes for ease of implementation, but the distinction between fullwidth and halfwidth is not the byte length used to represent a character. In various environments, including Unicode, both halfwidth and fullwidth characters may use variable-length or multibyte encodings.
In fixed-width type or fonts, a fullwidth character is twice as wide as a halfwidth character, but in variable-width environments it may not be exactly twice as wide.
Some characters have both a fullwidth form and a halfwidth form.
Fullwidth characters
Fullwidth is a square shape.
A character whose width is about twice the fixed width of an ordinary Latin letter.
Precomposed Hangul syllables, Chinese characters and hiragana are always fullwidth characters.
Halfwidth characters
Halfwidth is a rectangle with half the horizontal width of fullwidth.
A character whose width is half that of a fullwidth character is called a halfwidth character.
Switching in the IME
You can switch between fullwidth and halfwidth with the IME key Alt + Shift + '+' (Alt + = on Windows 10), but most people don't know this.
Typing a backslash () in fullwidth mode is said to input a fullwidth won sign, but it can also be entered with the ㄹ + 한자 keys (the jamo rieul followed by the Hanja key).