This is a list of the world's largest cities in population, ordered by several ranking methods. Determining the world's largest cities depends on which definitions of "city" and "size" are used, and how those definitions are applied. The "size" of a city can refer to its land area, but it is more typically the population. How one defines the land area of a city, however, is key to determining its population.
A city can be defined as a conditionally contiguousurban area, without regard to territorial or other boundaries inside an urban area. UNICEF defines urban area as follows:
The definition of "urban" varies from country to country, and, with periodic reclassification, can also vary within one country over time, making direct comparisons difficult. An urban area can be defined by one or more of the following: administrative criteria or political boundaries (e.g., area within the jurisdiction of a municipality or town committee), a threshold population size (where the minimum for an urban settlement is typically in the region of 2,000 people, although this varies globally between 200 and 50,000), population density, economic function (e.g., where a significant majority of the population is not primarily engaged in agriculture, or where there is surplus employment) or the presence of urban characteristics (e.g., paved streets, electric lighting, sewerage).
A formal local government area comprising the urban area as a whole and its primary commuter areas, typically formed around a city with a large concentration of people (i.e., a population of at least 100,000). In addition to the city proper, a metropolitan area includes both the surrounding territory with urban levels of residential density and some additional lower-density areas that are adjacent to and linked to the city (e.g., through frequent transport, road linkages or commuting facilities).
^The city proper based on the districts of Huangpu, Xuhui, Changning, Jing'an, Putuo, Zhabei, Hongkou and Yangpu considered "core districts"-the older part (Puxi) + Inner suburbs (districts): Jiading, Baoshan, Minhang and Pudong New Area.
^Beijing is one of the four direct-controlled municipalities of People's Republic of China, and is divided into 14 districts and 2 counties. The city proper based on the districts of Dongcheng and Xicheng considered "core districts" - the older part + Inner suburbs (districts): Chaoyang, Haidian, Fengtai and Shijingshan.
^The Lagos State is made up of 20 districts (3568 square kilometers). The Metropolitan Lagos (City proper) is made up of 16 districts: Agege; Ajeromi-Ifelodun; Alimosho; Amuwo-Odofin; Apapa; Eti-Osa; Ifako-Ijaye; Ikeja; Kosofe; Lagos Island; Lagos Mainland; Mushin; Ojo; Oshodi-Isolo; Shomolu; Surulere (1171 square kilometres).
^The surface of the Metropolitan Lagos is 1171 square kilometres, but 171 square kilometres is water (lagoon).
^The city, considered capital of Istanbul Province, is administered by the Istanbul Metropolitan Municipality (IMM), which oversees the thirty-nine districts of the city-province (thirty-six urban districts and three rural districts).
^According to the new Metropolitan Municipal Law (No.5216/2004-5), Jurisdiction of Istanbul Metropolitan Municipality (IMM), the city area is 5343.02 square kilometers. Districts: Çatalca, Silivri and Şile (total area 3153.23 square kilometers) are almost entirely rural.
^Guangzhou City is a sub-provincial city and it is divided into 10 districts and 2 County-level cities. Guangzhou is further divided into 131 Subdistricts and 38 Towns. The city proper (districtes): Yuexiu, Liwan, Haizhu, Tianhe, Baiyun, Huangpu, Panyu, Huadu and Industrial Districts - Nansha, Luogang.
^Mumbai City consists of two distinct regions: Mumbai City district (Island City) and Mumbai Suburban district (Western Suburban and Eastern Suburban), grouped into 24 wards, under the administration of Brihanmumbai Municipal Corporation (BMC). The remaining area belongs to Defence, Mumbai Port Trust, Atomic Energy Commission and Borivali National Park, which are out of the jurisdiction of the BMC.
^Dhaka City Corporation was established as the Dhaka Municipality on August 1, 1864. The Awami League government on 29 November 2011 dissolved the Dhaka City Corporation by the Local Government (City Corporation) Amendment Bill 2011 passed by the Parliament of Bangladesh after being placed in the Parliament on November 23. The city corporation will be split into two corporations, North and South. The municipal area of Dhaka city is under the jurisdiction of the Dhaka City Corporation (North - South) and the municipal area is divided into 92 wards.
^In April 2011, Prime Minister Essam Sharaf abolished the Helwan Governorate and reincorporated its territory into the Cairo Governorate. The total area of the governorate is 3085.1 square kilometers, the city area is 453 square kilometers, but the Egyptian government considered the Cairo Governorate is that a whole city and all statistics relate to the "governorate".
^Administratively, the Municipality of São Paulo is divided into 31 subprefectures, each in turn divided into 96 districts. Locally, districts may contain one or more neighborhoods (bairros). The city of São Paulo recognizes ten geographical areas used to reference locations in the city.
^The province of Kinshasa is divided into twenty-four districts, administered by the Metropolitan Municipality of Kinshasa. But the districts (communes) of Maluku and Nsele (N'Sele) are rural and not part of the city proper. The city proper (urban area) of Kinshasa is generally considered to be formed by twenty-two "communes".
^According to the Constitution of Democratic Republic of the Congo, the province of Kinshasa covers 9965.21 km2. Maluku and N'Sele (total area 8847.59 km2) are entirely rural, with a very very low density.
^Based on the districts of Heping, Hexi, Hebei, Nankai, Hedong, Hongqiao, Jinnan, Dongli, Xiqing, Beichen and Binhai New Area, considered "core districts". Starting from November 2009, Binhai New Area was consolidated into a district, and the former subordinate districts of Tanggu, Hangu and Dagang were abolished. Binhai is part of the Bohai Economic Rim and is expected to become another asset to regional development, following the rise of Shenzhen Special Economic Zone and Shanghai Pudong New Area. It is a Special Economic Zone (SEZ) of the PRC, meaning experimental reforms are taking place here.