Fullwidth Digit Four

It means four; fullwidth describes its spacing, not its value.

A standard trail for this fullwidth form reaches back to Japan’s 1978 JIS C 6226/JIS X 0208 character set, a 94×94 grid for symbols, digits, letters, kana (Japanese syllabic signs), and kanji (characters used in Japanese writing). In mixed-width text, many East Asian characters filled two display cells while a narrow 4 used one. Unicode retained the paired forms for conversion with those older encodings.

In Chinese, Japanese, and Korean text, this is a layout and encoding distinction, not a new number. A 2023 analysis of vaporwave text describes fullwidth strings as a deliberate visual style; one isolated ４ usually just reflects formatting or input mode.

Why is ４ wider than 4?

It fills a full East Asian text cell to align with nearby characters. A Japanese government registration guide, checked 2026-09-14, requires halfwidth digits in postal and phone fields while allowing mixed-width text in names and addresses. If a form rejects ４, use 4: it is enforcing a field-width rule.