The fen () in Mandarin, fan in Cantonese or hun in Taiwanese, is a traditional Chinese unit of length. One "fen" equals 1/10 of a "cun" or 1/100 of a "chi". It is 3+1⁄3 mm in China mainland, 3.71475 mm in Hong Kong and 3.030 mm in Taiwan.
Hong Kong and Macau.
These correspond to the measures listed simply as "China" in "The Measures, Weights, & Moneys of All Nations".
Taiwan.
Length measure in Taiwan is largely metric but some units derived from traditional Japanese units of measurement remain in use as a legacy of Japanese rule.
Taiwanese length units and the translation of length units in metric system (SI) shares the same character. The adjective "Taiwanese" () can be added to address the Taiwanese unis system. For example, means Taiwanese foot and means meter.