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Cities · South Korea · capital
Seoul, 
South Korea
22,490,482 people lived in Seoul in 2025. It is the 10th largest of the world's 12,138 cities, and the largest in South Korea, where it is the capital.
Like every city on this site, Seoul is counted as a built-up area seen from above rather than as a city government's territory. Why that changes the number.
Verified 2026-09-30 · 73 canaries
People · every five years · 1975 to 2050
How Seoul grew
For every 10 people in Seoul in 1975, there were 22.3 in 2025.
On the UN's projection it will have 21.2 million people in 2050.
projected (after 2025) · how sure the UN is: high moderate low
How to read this: one column every five years, 1975 to 2050; its height is the number of people. Hatched columns are the UN's projection. The thin strip beneath says how sure the UN is of each figure: the stronger the colour, the surer. A blank means the place was not on the UN's list of cities that year.
People · your family's years · 1975 to 2050
Seoul through your family’s years
Put in the years your family were born. You’ll see how many people lived in Seoul in each of those years, and when each of them turned 30.
South Korea · every city · 2025
Where it is
How to read this: Seoul is the dot in colour with a ring around it. The grey dots are the other cities of South Korea in 2025, 49 in all, each drawn with an area that matches its people. Countries next door are outlines only.
Area and built-up land · km²
How much land it covers
In 2025, Seoul covered 2,255 km², and buildings, roads and other built-up land covered 521 km² of it. That is 23 m² of built-up land for each person, about a square 5 by 5 metres. Since 1975, its built-up land has grown to 2.6 times its size, and its people are 2.2 times as many.
How to read this: each pale square is the city's whole area, the strong square inside it the part that is built on; one scale for all three, so a bigger square is more land. Hatched is the UN's projection.
Of every 100 people in South Korea
Its share of South Korea
Of every 100 people in South Korea in 2025, 44 lived in Seoul, which is 22.5 million people.
How to read this: shrink South Korea to 100 people and this is what you get. The coloured squares are the ones who would live in Seoul; the grey ones are everybody else, in other cities, in towns and out in the country.
Ranked by people · 2025
Cities of a similar size
In the world, 2025
- 6 Guangzhou China27,563,372
- 7 Cairo Egypt25,566,102
- 8 Manila Philippines24,735,305
- 9 Kolkata India22,549,738
- 10 Seoul22,490,482
- 11 Karachi Pakistan21,422,590
- 12 Mumbai India20,203,056
- 13 São Paulo Brazil18,949,790
- 14 Bangkok Thailand18,180,280
In South Korea, 2025
- 10 Seoul22,490,482
- 146 Busan3,263,221
- 213 Daegu2,334,446
- 331 Daejeon1,517,299
- 351 Gwangju1,441,495
- 588 Ulsan881,858
- 780 Cheongju-si690,333
- 814 Changwon665,772
- 848 Jeonju637,082
How to read this: the figure in front of a name is where that city stands among the 12,138 cities the UN counted in 2025, and each bar is its people, on one scale per list. Numbers are missing where a city has fewer than 300,000 people and so has no page of its own.
Apparatus
Sources and method
The figures for Seoul are the UN's own, at five-year steps: an estimate for each of 1975 to 2025, then projection to 2050. Projected years are drawn hatched, and the UN publishes no range of uncertainty for a city. What a city means here, how the UN measures one, and why that number can differ from the one Seoul publishes about itself: how the figures here are put together.
Sources: UN WUP 2025 · Natural Earth · flag-icons. Every source, its licence and how to cite it →
Verified 2026-09-30 · 73 canaries