Kowloon Walled City's early population fluctuated between zero and a few hundred, and began growing steadily shortly after World War II. However, there is no accurate population information available for much of the Walled City's later existence. Official census numbers estimated the Walled City's population at 10,004 in 1971 and 14,617 in 1981, but these figures were commonly considered to be much too low. Informal estimates, on the other hand, often mistakenly included the neighbouring squatter village of Sai Tau Tsuen. Population figures of about 50,000 were also reported.
A thorough government survey in 1987 gave a clearer picture: an estimated 33,000 people resided within the Walled City. Based on this survey, the Walled City had a population density of approximately 1,255,000 inhabitants per square kilometre (3,250,000 /sq mi) in 1987.