The Halfwidth and Fullwidth Forms block spans U+FF00–U+FFEF, 240 codepoints in Plane 0 (Basic Multilingual Plane). 225 are assigned in Unicode 16.0; the other 15 are reserved for future characters.
By script: Common (66), Katakana (55), Latin (52), Hangul (52).
By general category: 107 other letters (Lo), 26 uppercase letters (Lu), 26 lowercase letters (Ll), 18 other punctuation (Po), 11 math symbols (Sm), plus smaller groups.
The first 223 arrived in Unicode 1.1 (1993); later additions came in 3.2 (2).
225 characters here have compatibility decompositions: they are formatting variants of other characters and are replaced by them under NFKC and NFKD. See normalization.