FullWidth

Fullwidth refers to two related ideas in typography and layout. In East Asian typography, it denotes characters that occupy the same fixed square width as a CJK character, as opposed to narrow or halfwidth forms. In web and print design, the term describes elements that extend across the entire horizontal span of a page or container.

In Unicode, the Fullwidth Forms block (U+FF00 to U+FFEF) provides fullwidth variants of Latin letters, numbers and punctuation. These characters are designed to align with the grid of CJK glyphs, producing uniform line boxes. For example, the fullwidth exclamation mark U+FF01 and the fullwidth comma U+FF0C. The standard ideographic space U+3000 is a related fullwidth space. Halfwidth forms also exist, primarily for compatibility with legacy encodings.

In typography, fullwidth characters are commonly used in Japanese and other East Asian contexts to maintain vertical rhythm and alignment with surrounding CJK characters. Modern fonts often provide these glyphs automatically, though usage remains domain-specific (documents, software interfaces and data entry).

In layout and web design, a fullwidth element fills the available horizontal space, typically via CSS such as width: 100% or by using a full-bleed design. This contrasts with fixed-width columns or centered content. Fullwidth sections are common in responsive designs, allowing content to adapt to viewport size.

See also: halfwidth, fullwidth forms, full-bleed, Unicode Fullwidth Forms.