JAKARTA - Jakarta has recently become the world’s most populous city, according to new data from the United Nations. 

The U.N. World Urbanization Prospects 2025 report estimates that Greater Jakarta is now home to nearly 42 million people. It has overtaken Dhaka, which has nearly 37 million residents, and Tokyo, with about 33 million. Jakarta is the only city in Southeast Asia at the top of the global ranking.

This explosive growth is largely driven by internal migration, as Indonesians from rural areas and smaller towns move to the capital seeking jobs, education, and better access to services.

With that number, Jakarta’s population is more than double that of the Netherlands (around 18.35 million) and roughly four times that of Belgium (approx. 11.76 million) or Greece (10.28 million).

Jakarta on its own is also nearly a third of a country like the Philippines or Vietnam, about one-fifth of Mexico, one-fifth of Brazil, and roughly one-eighth of the United States.

But the Indonesian capital is slowly sinking due to excessive groundwater extraction, rising sea levels, and its location on low-lying swampy land. In some northern coastal areas, the ground has dropped by several meters over the past decades, and experts predict that parts of it will be underwater by 2050. 

Climate change and land subsidence are expected to increase internal migration even further, as residents may be forced to move to higher ground or to other cities. 

During the colonial era, what is now Jakarta was originally a low-lying swampy coastal area crisscrossed by rivers and canals. The land was muddy, flood-prone, and close to the sea, with mangroves and wetlands dominating the landscape

Because of this, the Indonesian government decided to move the national capital to a new city called Nusantara in East Kalimantan to reduce pressure on Jakarta. 

However, the relocation project is now in limbo. Funding has slowed, construction has stalled, and large parts of the new capital remain unfinished.

The report also said that the number of megacities, defined as urban areas with more than 10 million people, has grown from eight in 1975 to 33 in 2025. More than half of these megacities are located in Asia.