A 2013 study found that it was the 14th most common surname by 17,000,000 people, or 1,280% of the population, with the province with the most inhabitants being Jiangsu. The ancestral name (姓) of the ruling family of the state of Zhu (邾) was Cao. (p. 144, Xueqin). The State of Zu, as it was later renamed, was conquered and annexed by the State of Chu during the reign of King Xuan of Chu (369-340 BC). (p. 43, Chao). The ruling family and its descendants adopted Zhu (朱) as their surname in memory of their former state of Zhu (邾) (p. 43, Chao & p. 239, Tan). The most important of the five, Zhu (朱), is the 17th name in the poem One Hundred Surnames and was the surname of the emperors of the Ming Dynasty. It is alternately spelled Chu (mainly in Hong Kong, Macau and Taiwan), Gee[clarification needed] in the United States and Canada, and Choo (mainly in Singapore and Malaysia).
In 2018, it is the 14th. Most common surname in the People`s Republic of China with a population of about 18 million.    One interpretation is that 朱 refers to 朱雀, which means vermilion. This is a completely different character from another Chu (楚), which is less common than Zhu. Zhu (朱) is technically a branch of the surname Cao (曹). Nowadays, Zhu is the 14th most common, while Cao 27th is the most common in terms of population size.  Zhu is the pinyin romanization of five Chinese surnames: 朱, 祝, 竺, 猪 and 諸. During the Ming Dynasty, some Zhus moved to Taiwan, others later migrated to Southeast Asia, Europe and America.
The clan is also found in Korea and is known as: 주 (朱; Ju, Joo); It is the 32nd most common name in Korea, although it is combined with the surname Zhou (周). .