Japan vs South Korea
Japan has 2.4× the population of South Korea: 123,366,734 vs 51,684,564, a gap of 71.7 million. South Korea is shrinking more slowly (−0.13% vs −0.49% a year), adding about -66,458 people a year against −607,141. At these source-year rates the modelled relative population gap is narrowing, but too slowly to close within two centuries. Japan is the older society: 30.0% aged 65+ against 20.3% in South Korea. South Korea is 1.6× as densely populated (529.8 vs 341.5 people per km²).
Country/territory population bases: World Bank 2025 (Japan) and 2025 (South Korea); growth years 2025 / 2025. Annual source values, not live counts; years may differ. Growth is national, not local.
Japan vs South Korea — side by side
 Japan |  South Korea | |
|---|---|---|
| Population | 123,366,7342025 | 51,684,5642025 |
| Growth rate / yr | −0.49%2025 | −0.13%2025 |
| Births per 1,000 | 5.72024 | 4.72024 |
| Deaths per 1,000 | 13.32024 | 7.02024 |
| Children per woman | 1.152024 | 0.752024 |
| Life expectancy | 84.0 yrs2024 | 83.6 yrs2024 |
| Aged 0–14 | 11.2%2025 | 10.2%2025 |
| Aged 65+ | 30.0%2025 | 20.3%2025 |
| Density | 341.5 /km²2023 | 529.8 /km²2023 |
| Area | 377,969 km²2023 | 100,450 km²2023 |
| Urban population | 92.3%2025 | 81.2%2025 |
| Net migration / yr | +140,5792025 | +65,7312025 |
| GDP per capita | $35,9512025 | $36,2272025 |
| Country population rank (available records) | #12 | #29 |
| Base / world population (World Bank 2025) | 1.50% | 0.63% |
Highlighted cell = the higher value (not "better"). Small print under each value is its own data year. Source: World Bank; country/territory population bases may have different years. These are not live counts.
Population since 1960
World Bank population history (not the separate UN WPP timeline). Japan: 1.3× from 1960 to 2025; South Korea: 2.1× from 1960 to 2025. Left: absolute population. Right: each series indexed to its own first available year = 100; baseline years may differ.
More comparisons
Region: East Asia & Pacific · rankings
Japan: Japan vs India, Japan vs China, Japan vs United States, Japan vs Indonesia, Japan vs Pakistan, Japan vs Nigeria, Japan vs Brazil, Japan vs Bangladesh.
South Korea: South Korea vs India, South Korea vs China, South Korea vs United States, South Korea vs Indonesia, South Korea vs Pakistan, South Korea vs Nigeria, South Korea vs Brazil, South Korea vs Bangladesh.
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