The most populated city in the world is Jakarta, Indonesia, with about 41.9 million people in 2025, according to the United Nations' World Urbanization Prospects 2025. Dhaka in Bangladesh is second with 36.6 million and Tokyo third with 33.4 million, followed by Delhi (30.2 million), Shanghai (29.6 million), Guangzhou (27.6 million), Cairo (25.6 million), Manila (24.7 million), Kolkata (22.5 million) and Seoul (22.5 million). These are populations of whole urban areas, not of city limits, estimated for 1 July 2025 and published by the UN Population Division in November 2025.
If you learned that Tokyo is the biggest city on Earth, you weren't wrong when you learned it. Tokyo topped the UN's rankings for decades. What changed is partly the cities and partly the ruler used to measure them, and the UN's new data lets us replay the ranking year by year from 1975 to a projection for 2050. On that consistent yardstick, Jakarta drew level with Tokyo around 2010 and has pulled clearly ahead since, and Dhaka is on course to catch Jakarta in the late 2040s.
Why the old answer was Tokyo
The previous edition of the UN report, published in 2018, listed Tokyo first with 37 million people, ahead of Delhi with 29 million, according to the UN's 2018 key facts sheet. That edition took each country's own definition of a city or urban area, and those definitions varied widely: some drew generous lines around whole metropolitan regions, others counted little beyond the core city.
The 2025 edition throws those national definitions out for its city tables. It uses the Degree of Urbanisation, a method agreed by international statistics bodies, that works from satellite imagery and a grid of one-kilometre squares. A city is any patch of contiguous squares holding at least 1,500 people per square kilometre, with at least 50,000 people in total. Wherever the dense patch keeps going, the city keeps going, whatever the administrative map says. The UN also lowered its threshold for counting a place as a city from 300,000 people to 50,000, which is why the database now covers 12,138 cities.
Applied to Jakarta, the dense area spills far past the provincial boundary into neighbouring cities such as Bekasi, Depok and Tangerang, because the built-up land between them never thins out. The province of Jakarta itself had about 11.34 million residents in mid-2024, in Indonesia's civil-registry (Dukcapil) data as reported by Databoks. The dense urban area the UN measures is nearly four times that, spread over 4,883 km². Tokyo's urban area covers 5,148 km² but holds fewer people, at 6,490 per km² against Jakarta's 8,584.
Here are the 25 largest cities on that measure, with where each stood in 1975 and where the UN expects it in 2050.
| Rank | City | Country | 2025 | 1975 | 2050 (projected) | Rank 1975 | Rank 2050 | People per km² |
|---|---|---|---|---|---|---|---|---|
| 1 | Jakarta | Indonesia | 41.9M | 11.7M | 51.8M | 4 | 2 | 8,584 |
| 2 | Dhaka | Bangladesh | 36.6M | 5.0M | 52.1M | 22 | 1 | 5,371 |
| 3 | Tokyo | Japan | 33.4M | 24.3M | 30.7M | 1 | 7 | 6,490 |
| 4 | Delhi | India | 30.2M | 6.1M | 33.9M | 17 | 4 | 14,385 |
| 5 | Shanghai | China | 29.6M | 4.5M | 34.9M | 24 | 3 | 9,444 |
| 6 | Guangzhou | China | 27.6M | 1.6M | 29.2M | 88 | 8 | 6,069 |
| 7 | Cairo | Egypt | 25.6M | 7.4M | 32.4M | 14 | 6 | 15,542 |
| 8 | Manila | Philippines | 24.7M | 8.3M | 27.1M | 12 | 9 | 10,146 |
| 9 | Kolkata | India | 22.5M | 10.5M | 23.8M | 7 | 10 | 9,682 |
| 10 | Seoul | South Korea | 22.5M | 10.1M | 21.2M | 8 | 12 | 9,974 |
| 11 | Karachi | Pakistan | 21.4M | 4.6M | 32.6M | 23 | 5 | 24,624 |
| 12 | Mumbai | India | 20.2M | 8.3M | 23.1M | 11 | 11 | 27,301 |
| 13 | São Paulo | Brazil | 18.9M | 10.5M | 18.2M | 6 | 16 | 9,271 |
| 14 | Bangkok | Thailand | 18.2M | 3.7M | 20.5M | 31 | 13 | 6,832 |
| 15 | Mexico City | Mexico | 17.7M | 11.1M | 17.7M | 5 | 18 | 8,457 |
| 16 | Beijing | China | 17.0M | 5.2M | 18.0M | 21 | 17 | 9,932 |
| 17 | Lahore | Pakistan | 15.2M | 4.4M | 20.4M | 26 | 14 | 15,674 |
| 18 | Istanbul | Turkey | 15.0M | 5.3M | 16.3M | 20 | 20 | 11,841 |
| 19 | Moscow | Russia | 14.5M | 8.5M | 15.5M | 10 | 22 | 9,305 |
| 20 | Ho Chi Minh City | Vietnam | 14.1M | 2.4M | 17.2M | 54 | 19 | 9,090 |
| 21 | Buenos Aires | Argentina | 14.0M | 8.6M | 14.2M | 9 | 25 | 6,478 |
| 22 | New York City | United States | 13.9M | 12.1M | 13.2M | 3 | 28 | 5,173 |
| 23 | Shenzhen | China | 13.9M | 0.5M | 14.7M | 384 | 23 | 9,512 |
| 24 | Bengaluru | India | 13.2M | 2.4M | 14.3M | 55 | 24 | 20,541 |
| 25 | Osaka | Japan | 13.0M | 14.4M | 10.4M | 2 | 37 | 5,816 |
1975: the list Tokyo and Osaka led
Run the same method back to 1975 and the top of the table looks like a different planet. Tokyo had 24.3 million people. Second was Osaka with 14.4 million, and third New York with 12.1 million. There were 8 cities of ten million or more. Jakarta, at 11.7 million, was already fourth, which surprises people who assume its rise is recent.
Of the ten largest cities of 1975, only four are still in the top ten: Tokyo, Jakarta, Kolkata and Seoul. The rest have been pushed down the table by cities that barely registered fifty years ago. Delhi was 17th in 1975, Dhaka 22nd, Shanghai 24th and Guangzhou 88th.
Around 2010: Jakarta draws level with Tokyo
On the UN's series, the lines cross in 2010, when Jakarta was ahead by about 37,000 people, or 0.1%. That is far smaller than the uncertainty in any modelled estimate, so the honest reading is that the two were level around then; what is not in doubt is the gap since, which had grown to 8.5 million by 2025. Tokyo was still growing then, but slowly: between 2000 and 2010 it added about 226 thousand people a year, while Jakarta added about 700 thousand. Jakarta's urban area also more than doubled in extent between 1975 and 2025, from 2,114 km² to 4,883 km², as the farmland of the plain around the old city filled with housing, roads and factories.
Tokyo's population peaked at 33.7 million in 2020, on these figures, and has eased down since. Japan's population peaked in 2008 and has fallen every year since 2011, according to its Statistics Bureau, and the capital can no longer outgrow the country around it for long. The UN expects Tokyo to hold 30.7 million people in 2050, enough to rank only 7th.
The next handover is projected for 2049, when Dhaka edges past Jakarta. The two are expected to finish the period almost level, Dhaka at 52.1 million and Jakarta at 51.8 million in 2050, so small changes in either country's birth rates or migration could move the date by years. Shanghai is projected to climb to third with 34.9 million.
Dhaka, Shenzhen and the steepest climbs
Dhaka's rise is the clearest example of what drives the modern ranking. It had 5.0 million people in 1975, four years after Bangladesh's independence, and has multiplied 7.3 times since. Its garment industry, which grew from almost nothing in the late 1970s into one of the world's largest clothing exporters, drew millions of workers from the countryside. Rivers and low-lying wetland hem the city in, so it grew upward and outward into a dense, sprawling urban area of 6,812 km².
The fastest climb in the top 25 belongs to Shenzhen, which grew 28 times over, from 0.5 million to 13.9 million. In 1975 it was a cluster of fishing and farming villages on the border with Hong Kong. China made it a Special Economic Zone in 1980, and the factories and migrants followed. Its neighbour Guangzhou multiplied 17 times, from 1.6 million to 27.6 million, and now ranks sixth in the world.
Population density varies widely among these giants. The most crowded of the top 25 is Mumbai, at 27,301 people per km². It holds 20.2 million people on just 740 km², most of it on Salsette Island, hemmed in by the Arabian Sea and the creeks that separate it from the mainland; newer growth has jumped those creeks to Thane and Navi Mumbai. Dhaka, by comparison, has about a fifth as many people per square kilometre.
The giants that are already shrinking
Six of the 33 cities with ten million or more people in 2025 are projected to be smaller in 2050 than they are now: Tokyo, Seoul, São Paulo, Mexico City, New York City and Osaka. They share a pattern. Each is in a country where women now have fewer than about 2.1 children on average, the level that keeps a population stable, and where most of the move from countryside to city has already happened.
Osaka shows how far a city can slide without collapsing. It was the world's second-largest city in 1975, with 14.4 million people. It has 13.0 million today, which ranks 25th, and the UN projects 10.4 million by 2050. New York tells a similar story in rank rather than size: it actually grew, from 12.1 million to 13.9 million, yet fell from 3rd to 22nd because others grew so much faster. London, with 10.4 million, ranks 33rd.
Where the next megacities are rising
The number of megacities, cities of ten million or more, went from 8 in 1975 to 33 in 2025. The UN projects 37 by 2050. Nine of the top ten are in Asia, and the only exception is Cairo, with 25.6 million people strung along the Nile.
The cities projected to join the club by 2050 are Hajipur, Dar es Salaam, Addis Ababa and Kuala Lumpur. One name looks odd. Hajipur is a district town across the Ganges from Patna, in the Indian state of Bihar, and you won't find it on lists of famous cities. The UN's file credits it with 9.9 million people in 2025 because the grid method joins the densely settled villages of the surrounding plain into a single continuous patch. Rural Bihar is so crowded that, by satellite, much of it looks urban.
South of the Sahara, Africa's big cities sit further down the table but are growing fastest. Lagos ranks 26th with 12.8 million, Kinshasa has 10.9 million, and Luanda, with 11.4 million today, is projected to reach 20.3 million by 2050, a rise of 78% in 25 years.
How far to trust the figures
Every number on this page is a modelled estimate rather than a headcount. Censuses in many countries are years old, and the UN combines them with satellite imagery to estimate where people live. It also grades each city's figure for plausibility. Jakarta and Tokyo are rated high, while Dhaka is rated moderate.
Even the UN's own announcement rounded loosely. Its press release of 18 November 2025 described Dhaka as having almost 40 million people, while the published table gives 36.6 million. We use the table. The release's other headline figure checks out: the 12,138 cities in the database hold 3.69 billion people, or 45 percent of the world's 8.2 billion.
Other organisations draw city edges differently and get different rankings. Definitions built on commuting regions draw wider lines than the density grid, counting suburbs it leaves out, and so can produce a different order at the top. Neither approach is wrong; they answer different questions. The UN's method has one big advantage: it measures every city on Earth the same way, so a ranking built from it compares like with like.
The figures above cover the 511 cities with at least a million people in 2025, with populations every few years from 1975 to 2050 and coordinates for mapping; download the data as a CSV. To build charts like these from a spreadsheet of your own, try Parity. The sources are:
- UN DESA Population Division, World Urbanization Prospects 2025 (cities database, DEGURBA): mid-year population of every city of 50,000+, 1975–2050; released 18 November 2025; CC BY 3.0 IGO
- UN DESA press release, 18 November 2025
- Natural Earth land and country outlines (via world-atlas): public domain
For the same 33 cities grouped continent by continent, with how other counts arrive at 32 or 42, see our guide to every megacity over 10 million, or go deeper into the leader with the largest cities in Indonesia, where Jakarta's neighbours Bekasi and Tangerang rank as major cities in their own right.