Ask which city is the largest in the world and you can get at least four different, all technically correct, answers. Guangzhou, if you count its entire built-up urban footprint stretching into Shenzhen and Dongguan: 73.6 million people. Jakarta, if you use the UN’s newest satellite-based urban agglomeration method: nearly 42 million. Tokyo-Yokohama, if you use the more familiar metropolitan agglomeration figures most databases still report: 37 million. Delhi, by some metro-area rankings: 34 million. None of these sources is wrong. They are measuring different things, and the single most useful piece of information in any city population ranking is not the number itself but the boundary definition sitting quietly behind it.
What Makes a City One of the World’s Largest?
Four distinct geographic boundaries get used, often interchangeably and rarely labeled clearly, to measure a “city’s” population:
- City proper counts only the population within a city’s official administrative boundary, the legal jurisdiction governed by a single municipal authority. This is often the smallest and most restrictive figure, since many cities have long since sprawled beyond their formal administrative limits.
- Urban agglomeration counts the contiguous built-up area around a city, including suburbs and satellite towns that have physically merged into a single continuous urban footprint, regardless of how many separate municipal governments administer different parts of it. This is the measure the UN Population Division uses for its official World Urbanization Prospects rankings.
- Metropolitan area counts a functional economic region, typically defined by commuting patterns, that can extend well beyond the physically built-up area to include smaller towns whose residents work in the central city, even across gaps of open land.
- Built-up area (satellite-derived), a newer approach used in analyses like Visual Capitalist’s, uses satellite imagery to trace the actual continuous footprint of urban development, sometimes producing dramatically larger figures than agglomeration-based counts when a metropolitan region has effectively fused several formerly separate cities, as with the Pearl River Delta.
The UN itself is explicit on this point: there are no standardized international criteria for determining city boundaries, and multiple legitimate boundary definitions typically exist for any single urban area, which is precisely why competing “largest city” rankings can disagree so completely while each remaining internally consistent.
The World’s Largest Cities by Population
Using the UN Population Division’s own 2025 World Urbanization Prospects estimates, based on its urban agglomeration methodology, the current ranking looks like this:
Largest Urban Agglomerations, UN World Urbanization Prospects 2025
| Rank | City | Country | Population (approx.) |
|---|---|---|---|
| 1 | Jakarta | Indonesia | ~42 million |
| 2 | Dhaka | Bangladesh | ~37 million |
| 3 | Tokyo | Japan | ~33 million |
| 4 | Delhi | India | ~34 million (varies by source) |
| 9 | Kolkata | India | — |
Source: UN DESA, World Urbanization Prospects 2025: Summary of Results.
This represents a striking reshuffling from just 25 years earlier. In 2000, Tokyo led the world with 30.3 million inhabitants; Delhi ranked sixth and Kolkata actually outranked Delhi. By 2025, Jakarta has overtaken every city that once led the rankings, Delhi has climbed to fourth, and Kolkata has fallen to ninth, evidence of just how quickly the global urban hierarchy can reorder within a single generation.
A separate, still widely cited dataset, drawing on the UN’s earlier 2018-based estimates and reported via Statista and World Population Review, instead places Tokyo-Yokohama first at 37 million, followed by Delhi at over 34 million and Shanghai at over 30 million, illustrating how even among sources using broadly similar agglomeration methodology, the specific revision year and exact metropolitan boundary drawn can shift the ranking meaningfully.
The Largest Urban Agglomerations
When satellite-derived built-up area data is used instead of the UN’s administratively-informed agglomeration boundaries, the picture changes again, and changes dramatically for cities in China’s Pearl River Delta.
Largest Cities by Built-Up Area (Satellite and Census-Based)
| Rank | City | Country | Population (approx.) |
|---|---|---|---|
| 1 | Guangzhou (incl. Shenzhen, Dongguan, Foshan, Huizhou, Jiangmen, Zhongshan) | China | ~73.6 million |
| 2 | Shanghai | China | — |
| 3 | Tokyo | Japan | — |
| 4 | Delhi | India | ~31.4 million |
| 5 | Jakarta | Indonesia | — |
Source: Visual Capitalist, “Ranked: The 5 Largest Megacities in 2025, Based on Built-Up Area,” citing European Commission data via Our World in Data; Britannica, 2026 estimate.
Guangzhou’s built-up-area figure of 73.6 million dwarfs every agglomeration-based ranking because it merges what several other methodologies count as six or seven administratively distinct cities, Guangzhou, Shenzhen, Dongguan, Foshan, Huizhou, Jiangmen and Zhongshan, into a single continuous built environment. Since 1975, this combined urban footprint has grown by an almost unfathomable 1,948%, or nearly 20-fold, the fastest sustained urban expansion measured anywhere on Earth over that 50-year window, a direct consequence of China’s economic rise and its Pearl River Delta manufacturing boom.
The Largest Metropolitan Areas
Metropolitan-area rankings, which extend boundaries to include commuting hinterlands rather than only continuous built-up development, produce yet another distinct top ten. Britannica’s 2026 estimate of the ten largest metropolitan areas lists Guangzhou, Shanghai, Tokyo, Delhi, Jakarta, Mumbai, Manila, Mexico City, Seoul and Dhaka, a list that shares most of its members with the agglomeration and built-up-area rankings above but diverges meaningfully in exact order and in which secondary cities, Manila and Seoul among them, appear at all.
Where the World’s Biggest Cities Are Concentrated
Asia’s dominance of every major city-size ranking is not a coincidence of any single methodology; it holds true across all four boundary definitions. China and India alone account for a large share of the world’s 30 largest cities, including Shanghai, Guangzhou, Delhi and Mumbai, reflecting both countries’ enormous overall population bases and their sustained, decades-long rural-to-urban migration.
Africa’s largest cities, while not yet among the global top tier by population, are growing at the fastest rates recorded anywhere in the world. Cairo (25.5 million), Lagos (12.7 million), Luanda (11.7 million) and Kinshasa (10.9 million) currently lead the continent, and Luanda in particular has been expanding at an extraordinary annual rate of about 11% since 2000, the fastest sustained big-city growth rate on the planet, driven by high birth rates and rural-to-urban migration.
How City Populations Have Changed
The reordering of the world’s largest-cities ranking over the past quarter-century illustrates how much urban growth trajectories can diverge even among cities that started from broadly comparable positions. Tokyo, the world’s largest city as recently as 2000 and still effectively the largest through the mid-2010s, is now experiencing a population plateau, and in some recent-year comparisons a slight decline, a direct consequence of Japan’s aging demographics and shrinking overall national population. Delhi has followed almost the opposite trajectory, continuing sustained growth that UN projections from as early as 2018 anticipated would eventually push it past Tokyo into the top position, a milestone various estimates have placed as arriving anywhere from the late 2020s to already having occurred, depending on which specific dataset and revision year is consulted.
City Population Change Since 2000 (Selected Cities)
| City | 2000 Population (approx.) | Approx. 2025 Population | Change |
|---|---|---|---|
| Tokyo | 30.3 million (world’s largest) | ~33-37 million | plateauing/declining slightly |
| Delhi | ranked 6th globally | 4th, ~34 million | continuous strong growth |
| Kolkata | ranked ahead of Delhi | 9th | relative decline in ranking |
| Guangzhou (built-up area) | ~3.8 million equivalent | ~73.6 million (combined) | +1,948% |
Source: Deccan Herald, citing UN World Urbanization Prospects 2025; Visual Capitalist.
Why Some Cities Grow So Quickly
Several distinct mechanisms explain why particular cities have expanded so much faster than others, often operating in combination:
- Rural-to-urban migration remains the dominant driver in fast-growing cities across South Asia and Africa, pulling residents toward employment and services concentrated in major urban centers.
- Natural population increase, births exceeding deaths among a city’s existing residents, contributes substantially to growth in cities with young population structures, notably across sub-Saharan Africa.
- Administrative and metropolitan boundary expansion, as with Guangzhou’s absorption of neighboring manufacturing cities into a single continuous urban footprint, can produce enormous headline population increases without necessarily reflecting a proportional increase in genuinely new residents relative to what earlier, narrower boundaries would have counted.
- Economic concentration, where a city serves as a country’s dominant commercial, industrial or administrative hub, drawing migration disproportionately compared with smaller regional cities.
- Climate-related displacement, a documented factor behind Dhaka’s growth specifically, where between 300,000 and 500,000 rural migrants arrive annually, driven substantially by rising sea levels, riverbank erosion and soil salinization affecting Bangladesh’s low-lying agricultural regions.
Megacities Versus Large Cities
A megacity, conventionally defined by the United Nations as an urban agglomeration with 10 million or more inhabitants, sits at the top of a much broader hierarchy of large cities; not every large or fast-growing city has crossed that specific threshold, and the megacity classification is discussed in full detail in the companion article on world megacities. What is worth flagging here is that living in one of the world’s largest cities by absolute population, roughly 14% of the entire world’s population lives in a top-tier megacity as of the mid-2020s, is a fundamentally different experience from living in a smaller, faster-growing city, since infrastructure demands, governance complexity and economic concentration scale very differently once a single urban area crosses into the tens of millions.
Measuring City Population
Because no single, universally agreed boundary definition exists, the responsible way to read any “world’s largest city” ranking is to check which of the four methodologies described above it uses before comparing it against a different source’s list. A ranking using city-proper administrative boundaries will systematically undercount cities whose metropolitan population has sprawled well beyond old municipal lines, a pattern especially pronounced in cities with historic, tightly drawn city limits. A ranking using satellite-derived built-up area will tend to inflate figures for polycentric urban regions, like the Pearl River Delta, where several formerly distinct cities have physically merged. Understanding which definition underlies a given figure is not a minor technicality; it is the difference between Guangzhou being the world’s largest city at 73.6 million or ranking well behind Jakarta, Dhaka and Tokyo at a more conventional agglomeration-based figure.
Key Findings
- No single, universally agreed definition of “city” exists, producing at least four legitimate but different rankings depending on whether city-proper, urban agglomeration, metropolitan area or satellite-derived built-up area boundaries are used.
- By the UN’s own 2025 World Urbanization Prospects agglomeration methodology, Jakarta (about 42 million) now ranks as the world’s largest city, having overtaken Tokyo, which led as recently as 2000 with 30.3 million.
- By satellite-derived built-up area, Guangzhou, combined with six neighboring Pearl River Delta cities, is the world’s largest urban footprint at approximately 73.6 million, a figure that has grown nearly 20-fold since 1975.
- China and India together account for a large share of the world’s 30 largest cities by nearly every measurement standard.
- Luanda, Angola, is the fastest-growing major city in the world, expanding at roughly 11% annually since 2000, driven by high birth rates and rural-to-urban migration.
- Roughly 14% of the world’s entire population now lives in one of the world’s top-tier megacities as of the mid-2020s.
Frequently Asked Questions
1. What is the largest city in the world?
It depends on the boundary definition used. By the UN’s 2025 urban agglomeration methodology, Jakarta is the largest at about 42 million people. By satellite-derived built-up area, Guangzhou’s combined Pearl River Delta footprint is larger still, at roughly 73.6 million.
2. Which city has the largest population?
Using the most widely cited UN agglomeration figures, Jakarta currently ranks first, followed by Dhaka and Tokyo, though several other credible rankings place Tokyo-Yokohama, Delhi or Guangzhou first depending on methodology.
3. What is the difference between a city and a metropolitan area?
A city, in its strictest sense, refers to a formal administrative jurisdiction. A metropolitan area extends that boundary to include the broader functional economic region tied to the city by commuting patterns, often encompassing a much larger population than the city’s official limits.
4. How are city populations measured?
Through several distinct methods: administrative city-proper boundaries, continuous built-up urban agglomerations, functional metropolitan commuting regions, or satellite-imagery-based analysis of physical urban footprint, each of which can produce a meaningfully different population figure for the same city.
5. Why did Tokyo lose its position as the world’s largest city?
Tokyo’s population has plateaued and, in some recent comparisons, slightly declined, a consequence of Japan’s aging population and shrinking national birth rate, while cities like Jakarta and Delhi have continued growing steadily through migration and natural increase.
6. Which cities are growing the fastest?
Luanda, Angola, is currently the fastest-growing major city in the world, expanding at approximately 11% annually since 2000, followed by other rapidly growing African and South Asian cities including Dhaka, Kinshasa and Lagos.
7. How many people live in the world’s biggest cities?
Roughly 14% of the entire global population lives within one of the world’s top-tier megacities as of the mid-2020s, a figure that has grown substantially from around 10% just fifteen years earlier.
8. Why do city population rankings disagree so much between sources?
Because there is no standardized international definition of a city’s boundary. Different sources use city-proper, urban agglomeration, metropolitan area, or satellite-derived built-up area methodologies, each of which can produce substantially different population totals for the same city.
9. Which countries have the most large cities?
China and India together account for a substantial share of the world’s 30 largest cities, reflecting both countries’ enormous population bases and sustained decades of rural-to-urban migration.
10. Is Delhi expected to become the world’s largest city?
UN projections have anticipated Delhi eventually overtaking other major cities in population for several revision cycles, though the exact timing and Delhi’s precise current rank vary across different UN reports and alternative data sources.
Sources
- United Nations Department of Economic and Social Affairs (UN DESA), Population Division, World Urbanization Prospects 2025: Summary of Results
- Visual Capitalist, “Ranked: The World’s 30 Largest Cities by Population,” December 2025
- Visual Capitalist, “Ranked: The 5 Largest Megacities in 2025, Based on Built-Up Area,” December 2025, citing European Commission data via Our World in Data
- Britannica, “List of the World’s Largest Cities by Population,” 2026 estimate
- Statista, “Largest urban areas globally by population 2025,” citing World Population Review
- U.S. News & World Report, “These Are the 10 Largest Cities in the World,” citing UN World Urbanization Prospects 2018 Revision
- Deccan Herald, “33 megacities and counting,” citing UN World Urbanization Prospects 2025
