As a family name, In may be written with one hanja, meaning "mark" or "seal" (印; 도장 인).
It has two bon-gwan: Kyodong, which is an island in Incheon and Yonan, North Korea.
[1] The 2000 South Korean census found 20,635 people with this family name.
[2] In a study by the National Institute of the Korean Language based on 2007 application data for South Korean passports, it was found that 86.9% of people with this surname spelled it in Latin letters as In in their passports.
[3] People with this family name include: There are 29 hanja with the reading "in" on the South Korean government's official list of hanja which may be registered for use in given names; they are listed in the table at right.