It is romanized as Chi in Wade–Giles, and Kai or Gai in Cantonese.

Ji is listed 113th in the Song dynasty classic text Hundred Family Surnames.

[2] A 2013 study found it was the 316th-most common surname, being shared by 165,0000 people or 0.012% of the population, with the province with the most being Anhui.

According to the Song dynasty text Lushi, a lineage that descended from Yu the Great was enfeoffed at Ji 计, and adopted it as their surname.

[3] According to the Qing dynasty genealogy text Xingshi Kaolue (姓氏考略), another source of the Ji surname was the Zhou dynasty Dongyi state of Ju, whose capital was at Jijin (计斤, in present-day Jiaozhou, Shandong).