Jakarta Surpasses Tokyo as World's Most Populous City: A Deep Dive

Jakarta, the capital of Indonesia, has officially surpassed Tokyo to become the world's most populous city with nearly 42 million inhabitants, according to the latest World Urbanization Prospects 2025 report by the United Nations Department of Economic and Social Affairs. This milestone marks the first time a Southeast Asian metropolis has structurally overtaken major industrialized capitals.

Jakarta's Ascendancy: A Demographic Overview

Jakarta's rise to the top is a result of continuous and accelerated growth. Since 2000, the urban area has experienced an average population increase of nearly 2% annually, primarily fueled by internal migration. Millions of Indonesians are drawn to the capital by the promise of work, income, and services in a country exceeding 270 million people.

Economic Magnetism

Jakarta's economic significance also contributes to its magnetic appeal. The metropolitan area generates almost one-fifth of the national GDP (approximately 20%), concentrating banking, commerce, finance, manufacturing, electronics, automotive, chemical, and biomedical industries. This attracts a workforce from across the Indonesian archipelago, one of the world's most populous countries.

Unlike other mature metropolises, however, this growth has not been matched by adequate urban planning. The city has expanded through accumulation, incorporating peripheries, suburbs, and informal communities that are now fully interconnected with the center.

The Shifting Sands of Urban Measurement

Jakarta's leap to the top of the global rankings is also linked to a methodological change introduced by the UN. Previous rankings relied heavily on national statistics, which were often inconsistent. The new approach uses consistent criteria to define cities, urban areas, and rural zones, including densely populated communities previously excluded. In Jakarta's case, this has meant accounting for tens of millions of people living in satellite districts and large informal settlements, the so-called kampung, often invisible in official statistics but essential to the metropolis's economic functioning.

Global Urbanization Trends

Jakarta's primacy fits into a clear global picture. Today, about 45% of the world's population lives in urban areas: over 3.7 billion people. In 1950, it was just 20%. Megacities, cities or agglomerations with more than 10 million inhabitants, have grown to 33 in 2025, compared to 8 in 1975.

According to UN data from 2025, the ten most populous cities on the planet are:

The World's Most Populous Cities in 2025

Here’s a snapshot of the top urban centers:

Following Jakarta, Dhaka is projected to become the world's most populous city by 2050, while Tokyo continues to lose inhabitants due to demographic aging. This reversal reflects two opposing trends: accelerated expansion in emerging countries and contraction in mature economies.

Asia's Urban Dominance

Nine out of ten megacities are located in Asia, with Cairo being the only non-Asian exception. This confirms that the global demographic center of gravity has now shifted permanently towards emerging countries.

The Absence of Italian Cities

No Italian cities appear in the 2025 ranking. The most populous remains Rome, with about 2.75 million inhabitants, an order of magnitude now distant from the dynamics of the large Asian megacities.

Yet, this was not always the case. In 1975, Naples, Milan, and Rome were among the top hundred most populous cities in the world. The year 2000 was the last time an Italian city, Naples, appeared in that ranking. Since then, demographic decline and urban stagnation have progressively distanced Italy from the major global rankings.

Jakarta's Hidden Vulnerabilities

Behind Jakarta's record numbers, however, lies an extremely vulnerable urban reality. Jakarta stands at an average altitude of about 11 meters above sea level and is hit every year by torrential rainy seasons that cause extensive flooding, especially in the northern area facing the Java Sea.

Disorderly growth has congested traffic, overloaded the sewage system, and aggravated air pollution. Millions of people live in high-density neighborhoods without essential services such as potable water, stable electricity, and waste disposal systems. The pressure on infrastructure is constant and growing.

The Sinking City

The most serious problem, however, is invisible to the naked eye. Jakarta is sinking. In some areas, the ground is subsiding up to 30 centimeters a year, one of the highest rates of subsidence in the world. The main cause is the uncontrolled extraction of water from underground aquifers. Only a portion of the population is connected to the official water network, while the rest obtains supplies by digging illegal wells. This empties the subsoil, accelerates the compaction of sandy and clayey soils, and makes the city increasingly unstable.

Climate change further aggravates the situation. Rising sea levels and increasingly unpredictable rainfall increase the risk of permanent flooding. Estimates cited in UN reports indicate that up to a third of the city could be underwater by 2050.

Indonesia's Bold Move: A New Capital

Faced with a crisis considered irreversible, Indonesia has chosen a drastic path: transferring the administrative capital away from Jakarta. This is how Nusantara, a newly founded city, is taking shape in East Kalimantan, on the island of Borneo, over 1,200 kilometers from the current capital.

Nusantara: A Vision for the Future

Intended as a green, sustainable, and low-emission capital, Nusantara should alleviate the demographic and infrastructural pressure on Jakarta and ensure long-term institutional stability. However, the path between ambition and reality is not simple. The costs of the project are high, the participation of private investors is proceeding more slowly than expected, and there are environmental concerns, mainly related to the impact on the tropical forest.

Timeline and Challenges

The transfer of the Capital was officially approved in 2022, when the construction sites were already open. A first symbolic inauguration was held in 2024 in a still incomplete city, with much of the infrastructure under construction. According to government estimates, the work will not be completed before 2045.

The new capital extends over approximately 2,650 square kilometers and, according to the executive, will become a hub of innovation and sustainability.

The Paradox of Jakarta

Jakarta today embodies the paradox of global urbanization. It is the most populous city on the planet, but also one of the most exposed, vulnerable, and unstable. It expands relentlessly while the ground gives way beneath its weight; it attracts millions of people in search of opportunity while, literally, sliding downwards.

Lessons from a Megacity

Indonesia's capital tells a cautionary tale of what happens when city growth outpaces planning, when infrastructure chases emergencies, and when the environment presents the bill. The future of megacities depends not only on numbers but also on their ability to remain livable, resilient, and socially sustainable. A city can become the largest in the world, but without balance, it risks collapsing under its own success.

Population Density of Major Cities (People per sq km)

This table illustrates how densely populated these urban areas are:

Projected Population Growth (2025-2035)

Forecasts indicate notable shifts in urban populations over the next decade: