The fen (Chinese: 分; pinyin: fēn) 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.