Jang, Chang and (less often) Zang are romanizations of the common Korean surname 장.
[1] In a study by the National Institute of the Korean Language based on 2007 application data for South Korean passports, it was found that 84.5% of people with this surname spelled it in Latin letters as Jang in their passports.
Rare alternative spellings included Jahng and Jean.
[3] Jang is a relatively common surname in the United States and was listed 5,531st overall during the 2000 US Census, and 11th among Asian and Pacific Islanders in 2000.
[4] In China, the Chinese surnames Zhang (Hanja 張), Zhang (章), Zhuang (莊) and Jiang (蔣) use the same Chinese characters as the Korean surname Jang.