United States vs South Korea: Population Comparison 2025
Allies with opposite trends. South Korea's record-low fertility vs US stability.
United States
South Korea
Population Pyramids Comparison
Total Population
United States
347.3M
South Korea
51.7M
Youth (0-14)
United States
17.1%
South Korea
10.2%
Elderly (65+)
United States
18.4%
South Korea
20.3%
Demographic Analysis: United States vs South Korea
In 2025, United States has a population of 347M, while South Korea has 52M. This represents a difference of 296M, with United States having 6.7 times the population of the other. United States ranks #3 globally by population size, while South Korea ranks #29.
The median age reveals significant demographic differences: United States has a median age of 39.5 years, compared to 46.7 years in South Korea. This 7.2-year difference indicates that South Korea has a significantly older population, with important implications for workforce dynamics, healthcare needs, and economic development. The dependency ratio in United States is 55.0%, 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: United States has a sex ratio of 100.99 males per female, while South Korea has 99.55. United States 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 | United States | South Korea | Difference / Ratio |
|---|---|---|---|
| Population Metrics | |||
| Total Population (2025) | 347M | 52M | 6.7x larger |
| World Population Ranking | #3 | #29 | 26 places apart |
| Population Growth Rate (5-year) | +0.46% | -0.07% | 0.53pp difference |
| Projected Growth (2025-2050) | 0.00% | 0.00% | 0.00pp difference |
| Age Structure | |||
| Median Age | 39.5 years | 46.7 years | 7.2 years younger |
| Youth (0-14) Population | 17.1% | 10.2% | 6.9pp difference |
| Working Age (15-64) Population | 64.5% | 69.5% | 5.0pp difference |
| Elderly (65+) Population | 18.4% | 20.3% | 1.9pp difference |
| Youth Bulge (15-29) | 19.7% | 16.4% | 3.3pp difference |
| Prime Workforce (25-54) | 39.1% | 43.4% | 4.3pp difference |
| Demographic Indicators | |||
| Total Dependency Ratio | 55.0% | 44.0% | 11.0pp difference |
| Child Dependency Ratio | 26.5% | 14.7% | 11.8pp difference |
| Old-Age Dependency Ratio | 28.5% | 29.3% | 0.8pp difference |
| Sex Ratio (males per 100 females) | 101.0 | 99.5 | 1.4 difference |
| Total Fertility Rate | 1.60 children/woman | 0.72 children/woman | 0.88 difference |
| Estimated Birth Rate | 10.7 per 1,000 | 4.8 per 1,000 | 5.9 difference |
| Aging Index (65+/0-14) | 107.5% | 199.2% | 91.7pp 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 United States and South Korea for each age group, split by gender:
Left Side (Males)
Blue = United States has more males
Green = South Korea has more males
Right Side (Females)
Pink = United States 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
295.6M
United States larger
Growth Since 1950
United States
+125.2%
South Korea
+161.5%
Population Ratio
1 : 0.15
United States : South Korea
| Metric | United States | South Korea | Difference |
|---|---|---|---|
| Total Population | 347.3M | 51.7M | +572.1% |
| Median Age | 39.5 years | 46.7 years | -7.2 |
| Youth Population (0-14) | 59.4M 17.1% | 5.3M 10.2% | +1026.3% |
| Working Age (15-64) | 224.0M 64.5% | 35.9M 69.5% | +524.2% |
| Elderly Population (65+) | 63.9M 18.4% | 10.5M 20.3% | +507.9% |
| Total Dependency Ratio | 55.0 per 100 | 44.0 per 100 | +11.0 |
| Youth Dependency Ratio | 26.5 per 100 | 14.7 per 100 | +11.8 |
| Old-Age Dependency Ratio | 28.5 per 100 | 29.3 per 100 | -0.8 |
| Sex Ratio | 101.0 M/100F | 99.5 M/100F | +1.4 |
| Population Structure Type | Constrictive | Constrictive | Same |
Total Population
United States
347.3M
South Korea
51.7M
Median Age
United States
39.5 years
South Korea
46.7 years
Youth Population (0-14)
United States
59.4M
17.1%
South Korea
5.3M
10.2%
Working Age (15-64)
United States
224.0M
64.5%
South Korea
35.9M
69.5%
Elderly Population (65+)
United States
63.9M
18.4%
South Korea
10.5M
20.3%
Total Dependency Ratio
United States
55.0 per 100
South Korea
44.0 per 100
Youth Dependency Ratio
United States
26.5 per 100
South Korea
14.7 per 100
Old-Age Dependency Ratio
United States
28.5 per 100
South Korea
29.3 per 100
Sex Ratio
United States
101.0 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 United States's centuries-long reign