These will be the world's biggest cities in 2030

Population in 2018: 15.4 million

Population in 2015: 13.5 million

Note: Lagos State includes eight local municipalities.

Population in 2015: 13.2 million

Note: Kinshasa includes four districts, which are further divide into 24 communes.

Population in 2015: 21.7 million

Note: Greater Sao Paulo includes 39 smaller municipalities.

Population in 2015: 21.6 million

Note: Mexico City's metro area includes 76 municipalities.

Population in 2015: 19.6 million

Note: Greater Beijing includes the Beijing and Tianjin municipalities and Hebei Province.

Population in 2015: 20 million

Note: Greater Mumbai consists of nine local governing bodies and 15 smaller municipal councils.

Population in 2015: 20.1 million

Note: Greater Cairo includes the city of Cairo, as well as the surrounding districts of Giza and Qalyubia.

Population in 2015: 19.6 million

Note: Greater Dhaka includes four districts and 11 smaller sub-units of districts.

Population in 2015: 25.6 million

Population in 2015: 37.5 million

Note: Greater Tokyo includes 23 smaller districts. The metro area is the only one in the top 13 that the UN predicts will see a decrease in population by 2030.

Population in 2015: 28.5 million

Note: Greater Delhi includes satellite cities including Faridabad, Gurgaon, Bahadurgarh, Noida, and Ghaziabad.