Place comparison

Seoul compared with Tokyo’s 23 wards: area, population and density

Seoul Special City and Tokyo’s 23 special wards land within a few per cent of each other on all three measures — area, population and average density.

Place A Grouped by country or region Place B Grouped by country or region

Equal-area outline comparison

Outlines are centered and scaled by official land area; position does not show geographic location.

Area

Population

Population density

Area data date

Population data date

The detailed guide below compares Seoul with Tokyo 23 Special Wards. Use the selector above to explore any other pair.

Direct answer

How different are Seoul and Tokyo 23 Special Wards?

Seoul covers 605.2 km²; Seoul's area is about 96.4% of Tokyo 23 Special Wards's. Its reported population is 9,335,444; Seoul's population is about 94.5% of Tokyo 23 Special Wards's. By average density, Seoul's population density is about 98% of Tokyo 23 Special Wards's.

Area difference

Seoul's area is about 96.4% of Tokyo 23 Special Wards's 605.2 km² · 627.5 km²

Population difference

Seoul's population is about 94.5% of Tokyo 23 Special Wards's 9,335,444 · 9,873,999

Density difference

Seoul's population density is about 98% of Tokyo 23 Special Wards's 15,425.4 /km² · 15,735.2 /km²

On a familiar scale

Seoul ≈ 56% of Changhua County 65 m² of land per resident
Tokyo 23 Special Wards ≈ 58% of Changhua County 64 m² of land per resident

Reference scales come from Department of Household Registration, Ministry of the Interior: Land area, households and population density by township and district (year-end 2025) , as of 2025-12-31.

How to read it

Two capital cores that turn out to be nearly the same size, with nearly the same number of residents, at nearly the same density.

Geography and shape

Both are the dense administrative core of a much larger metropolitan region, and both sit on a river plain that shaped where the city could grow. Seoul is split by the Han River and ringed by mountains that cap its outward growth; the 23 wards spread across the Tokyo lowland to the bay, with reclaimed land on the waterfront. The outlines are close enough in size that the comparison is really about what each core excludes.

Population context

The resident totals differ by about five per cent, and because the land areas are also close, the average densities end up within two per cent of each other. That symmetry is unusual and worth stating plainly: on these three measures the two cores are effectively the same object at different coordinates.

Boundaries and definitions

Neither figure is the metropolitan region. Seoul Special City is one city government of 25 districts; the Seoul Capital Area including Incheon and Gyeonggi is roughly twenty times larger and holds about 26.3 million people. Tokyo’s 23 wards are a statistical aggregate of 23 independent local authorities; Tokyo Metropolis adds 26 cities, 13 towns and villages and the Izu and Ogasawara islands. The population concepts also differ: Seoul uses a register-based census, the wards use an official estimate.

Seoul: Seoul Special City, the 25-district city government of 605.2 km². It is not the Seoul Capital Area, the commuter region of Seoul, Incheon and Gyeonggi Province, which is roughly twenty times larger and holds about 26.3 million people. Population is the 2024 register-based census total: everyone usually resident inside the city boundary on 1 November 2024, including 367,291 foreign residents, which is a different universe from the resident-registration series readers may know. Area is registered cadastral land at 31 December 2024, summed from the ministry's parcel-level file because no single line publishes the city total; the same method reproduces South Korea's national figure exactly. The two reference dates are two months apart.

Tokyo 23 Special Wards: The 23 special wards only, not Tokyo Metropolis and not the wider Greater Tokyo area. The wards hold about 70% of the metropolis population on under 30% of its land; the metropolis additionally contains 26 cities, 13 towns and villages and the Izu and Ogasawara islands. The area is a Geospatial Information Authority reference value because five wards have partly undetermined boundaries, and it includes 4.68 km² of river-mouth and bay landfill not assigned to any individual ward. Daytime population is far larger than the resident count: the 2020 census recorded 12.35 million people in the wards on a weekday.

In-depth guide

How should Seoul and Tokyo 23 Special Wards be understood in context?

Two capital cores that turn out to be nearly the same object: land, residents and average density all sit close together. The useful part of this page is therefore not which side is larger, but what each of the two figures leaves out.

A symmetry worth remembering

Seoul Special City is 605.2 km² with 9,335,444 residents; the 23 special wards are 627.51 km² with 9,873,999. Area, population and the average density that follows from them all land within about five per cent of each other. That is unusual for two places paired by reputation rather than by measurement, and it is worth remembering as a reference point.

Because all three measures agree, no single one of them carries a verdict. Differences this small also sit inside the ordinary uncertainty of the two sources, so a reader should treat the closeness as closeness rather than as a narrow win for either side. The interesting claim here is the resemblance itself.

Neither figure is the metropolitan region

Seoul Special City is one city government of 25 districts. The Seoul Capital Area, which adds Incheon and Gyeonggi, covers roughly 11,876 km² and holds 26,307,956 people. Tokyo Metropolis is 2,199.94 km² with 14,192,184, adding cities, towns and villages and the Izu and Ogasawara islands to the 23 wards.

In ordinary use, “Tokyo” almost never means the 23 wards. A figure found elsewhere and labelled Tokyo is therefore likely to describe a much larger object than this page does. Check which definition it uses before concluding that two sources disagree.

The two population counts are built differently

Seoul reports a register-based census; the wards report an official estimate. Both are official and both are defined consistently over time, but they are not produced by the same machinery. Keep that note attached whenever the two totals are quoted side by side.

Daytime commuter populations sit outside both counts. Each figure describes where people are registered or estimated to live, not how many are present on a working afternoon. For that question a daytime population series is the right source, and it exists separately on both sides.

Questions people ask

About this geographic comparison

Are Seoul and Tokyo really the same size?

Seoul Special City and Tokyo’s 23 wards are, to within a few per cent. But "Tokyo" more often means Tokyo Metropolis or Greater Tokyo, both of which are far larger, so the answer depends entirely on which Tokyo is meant.

Which is more crowded?

Their average densities are within about two per cent, which is too close to call from these figures alone. Neither average describes a particular district, and daytime commuter populations are outside both counts.

Do both counts include foreign residents?

Yes. Seoul’s census total includes 367,291 foreign residents, and Tokyo’s estimate is built on a census base that counts usual residents regardless of nationality.

Sources

Outline data: