New UN research shows that Jakarta has overtaken Tokyo to become the world’s most populous city. According to the World Urbanisation Prospects 2025 report, compiled by the Department of Economic and Social Affairs, the Indonesian capital is home to 42 million people. Dhaka ranks second with 37 million. Tokyo—whose metropolitan area in the study includes three neighbouring prefectures—has slipped to third place with 33 million residents. These findings diverge sharply from the 2018 estimates, when the Japanese capital topped the ranking with 37 million people.
The reshuffling reflects a new methodology the UN introduced to standardise the boundaries of urban, rural and other areas. Patrick Gerland, head of population estimates and projections, said previous studies relied on national data shaped by widely varying definitions, which consistently placed Tokyo in the lead. The new approach, he noted, “provides a more internationally comparable delineation of urban agglomerations based on unified demographic and geospatial criteria.”
The report notes that the number of city dwellers has more than doubled since 1950, when 20% of the world’s 2.5 billion people lived in urban areas. Today, nearly half of the global population—8.2 billion—resides in cities. By 2050, two-thirds of population growth will occur in urban centres, with most of the remaining third concentrated in small towns and settlements.
The number of megacities with populations of 10 million or more has risen from eight in 1975 to 33 in 2025. Nine of the world’s ten largest cities—Jakarta, Dhaka, Tokyo, New Delhi, Shanghai, Guangzhou, Cairo, Manila, Kolkata and Seoul—are located in Asia. “Urbanisation is a defining force of our time,” said Li Junhua, the UN’s Under-Secretary-General for Economic and Social Affairs. “With an inclusive and deliberate approach, it can become a source of transformative solutions for climate, the economy and social justice.”
Tokyo’s population, defined as a metropolitan agglomeration, includes the neighbouring prefectures of Saitama, Chiba and Kanagawa. The latter is home to Yokohama, a city of 3.7 million. Under the new criteria, Tokyo remained the world’s largest city until around 2010, when it was surpassed by Jakarta. While the broader Tokyo region used in the study has in recent years mirrored Japan’s nationwide demographic decline, the capital itself is moving in the opposite direction.
According to the metropolitan government, the combined population of the 23 special wards and 26 small cities that make up what is known as “Tokyo proper” now exceeds 14 million, up from 13.2 million a decade ago. Internal migration slowed during the Covid-19 pandemic but has since rebounded, driven by an inflow of young people seeking education and employment, the interior ministry notes.