Japan vs South Korea: Population Comparison 2025
World's fastest aging societies. Both face record-low fertility and shrinking workforces.
Japan
South Korea
Population Pyramids Comparison
Total Population
Japan
123.1M
South Korea
51.7M
Youth (0-14)
Japan
11.2%
South Korea
10.2%
Elderly (65+)
Japan
30.0%
South Korea
20.3%
Demographic Analysis: Japan vs South Korea
In 2025, Japan has a population of 123M, while South Korea has 52M. This represents a difference of 71M, with Japan having 2.4 times the population of the other. Japan ranks #12 globally by population size, while South Korea ranks #29.
The median age reveals significant demographic differences: Japan has a median age of 50.8 years, compared to 46.7 years in South Korea. This 4.1-year difference indicates that Japan has a significantly older population, with important implications for workforce dynamics, healthcare needs, and economic development. The dependency ratio in Japan is 70.2%, while in South Korea it is 44.0%, showing the relative burden of non-working age populations on the workforce.
Gender balance differs between the two countries: Japan has a sex ratio of 95.15 males per female, while South Korea has 99.55. South Korea shows a higher proportion of males, which can affect marriage markets, labor force composition, and social dynamics. These ratios reflect various factors including sex-selective practices, differential mortality rates, and migration patterns.
Comprehensive Demographic Comparison 2025
| Indicator | Japan | South Korea | Difference / Ratio |
|---|---|---|---|
| Population Metrics | |||
| Total Population (2025) | 123M | 52M | 2.4x larger |
| World Population Ranking | #12 | #29 | 17 places apart |
| Population Growth Rate (5-year) | -0.51% | -0.07% | 0.44pp difference |
| Projected Growth (2025-2050) | 0.00% | 0.00% | 0.00pp difference |
| Age Structure | |||
| Median Age | 50.8 years | 46.7 years | 4.1 years older |
| Youth (0-14) Population | 11.2% | 10.2% | 1.0pp difference |
| Working Age (15-64) Population | 58.8% | 69.5% | 10.7pp difference |
| Elderly (65+) Population | 30.0% | 20.3% | 9.7pp difference |
| Youth Bulge (15-29) | 14.5% | 16.4% | 1.8pp difference |
| Prime Workforce (25-54) | 36.0% | 43.4% | 7.4pp difference |
| Demographic Indicators | |||
| Total Dependency Ratio | 70.2% | 44.0% | 26.2pp difference |
| Child Dependency Ratio | 19.1% | 14.7% | 4.4pp difference |
| Old-Age Dependency Ratio | 51.0% | 29.3% | 21.8pp difference |
| Sex Ratio (males per 100 females) | 95.2 | 99.5 | 4.4 difference |
| Total Fertility Rate | 1.20 children/woman | 0.72 children/woman | 0.48 difference |
| Estimated Birth Rate | 6.4 per 1,000 | 4.8 per 1,000 | 1.5 difference |
| Aging Index (65+/0-14) | 266.9% | 199.2% | 67.7pp difference |
| Population Pyramid Type | constrictive | constrictive | Same type |
📊 Understanding the Population Difference Chart
This visualization shows where and by how much the populations differ between Japan and South Korea for each age group, split by gender:
Left Side (Males)
Blue = Japan has more males
Green = South Korea has more males
Right Side (Females)
Pink = Japan has more females
Orange = South Korea has more females
💡 How to Read: Each age group shows up to 2 bars - one on the left (male difference) and one on the right (female difference). The bar's color tells you which country has more people, and the bar's length shows by how much. For example, if you see a green bar on the left, it means South Korea has more males in that age group.
Notable Differences (>20% variance):
Population Difference
71.4M
Japan larger
Growth Since 1950
Japan
+42.4%
South Korea
+161.5%
Population Ratio
1 : 0.42
Japan : South Korea
| Metric | Japan | South Korea | Difference |
|---|---|---|---|
| Total Population | 123.1M | 51.7M | +138.3% |
| Median Age | 50.8 years | 46.7 years | +4.1 |
| Youth Population (0-14) | 13.8M 11.2% | 5.3M 10.2% | +162.4% |
| Working Age (15-64) | 72.3M 58.8% | 35.9M 69.5% | +101.6% |
| Elderly Population (65+) | 36.9M 30.0% | 10.5M 20.3% | +251.5% |
| Total Dependency Ratio | 70.2 per 100 | 44.0 per 100 | +26.2 |
| Youth Dependency Ratio | 19.1 per 100 | 14.7 per 100 | +4.4 |
| Old-Age Dependency Ratio | 51.0 per 100 | 29.3 per 100 | +21.8 |
| Sex Ratio | 95.2 M/100F | 99.5 M/100F | -4.4 |
| Population Structure Type | Constrictive | Constrictive | Same |
Total Population
Japan
123.1M
South Korea
51.7M
Median Age
Japan
50.8 years
South Korea
46.7 years
Youth Population (0-14)
Japan
13.8M
11.2%
South Korea
5.3M
10.2%
Working Age (15-64)
Japan
72.3M
58.8%
South Korea
35.9M
69.5%
Elderly Population (65+)
Japan
36.9M
30.0%
South Korea
10.5M
20.3%
Total Dependency Ratio
Japan
70.2 per 100
South Korea
44.0 per 100
Youth Dependency Ratio
Japan
19.1 per 100
South Korea
14.7 per 100
Old-Age Dependency Ratio
Japan
51.0 per 100
South Korea
29.3 per 100
Sex Ratio
Japan
95.2 M/100F
South Korea
99.5 M/100F
Note: Dependency ratios represent the number of dependents (youth + elderly) per 100 working-age individuals. Higher ratios indicate greater economic burden on the working population.
Note: The replacement fertility rate of 2.1 is the level at which a population exactly replaces itself from one generation to the next.Both countries are experiencing demographic transitions as they develop economically. Countries below 2.1 face potential population decline without immigration, while those above 2.1 continue growing naturally.
Historic Milestone: 2023
South Korea became the world's most populous country, ending Japan's centuries-long reign