Calculated from the UN's 2024 World Population Prospects, the country with the highest share of people aged 65 and over in 2025 is Japan (30.0%). That means three in every ten people are 65 or older. South Korea is 26th at 20.3%.
The common reading is that 'old countries are a Japan and Europe story'. But the 2035 projection, ten years out, changes the picture. South Korea reaches 29.6% and ranks third, behind Japan and Italy. What matters is not today's rank but the speed of aging.
- What makes a country count as 'aging'?
The UN groups countries by the share of the population aged 65 and over. At 7% or more it is an aging society, at 14% or more an aged society, and at 20% or more a super-aged society. Every country in the Top 10 below is a super-aged society above 20%.
South Korea became an aging society in 2000 and an aged society in 2017. On Dec. 23, 2024, the registered population aged 65 and over reached 10,244,550, passing 20%. As of the end of 2024, that puts it second in Asia behind Japan. Going from an aged society to a super-aged society took Germany 37 years and France 39 years, but South Korea took 7 years.
Put simply, South Korea went through in 7 years a change that took Germany and France more than a generation.
- Which 10 countries are the oldest today?
The ranking covers the 156 UN member states with a 2025 population of 1 million or more. Very small countries such as Monaco, and territories that are not countries such as Hong Kong and Puerto Rico, are left out. The figures come from the medium variant of the UN's World Population Prospects 2024 (the scenario judged most likely).
| Rank | Country | Share of population 65+ in 2025 | Rank in 2035 |
|---|---|---|---|
| 1 | Japan | 30.0% | No. 1 |
| 2 | Italy | 25.1% | 2nd |
| 3 | Portugal | 24.9% | 5th |
| 4 | Greece | 24.4% | 6th |
| 5 | Finland | 24.2% | 11th |
| 6 | Germany | 23.7% | 4th |
| 7 | Croatia | 23.6% | 10th |
| 8 | Serbia | 23.1% | 16th |
| 9 | Bosnia and Herzegovina | 22.9% | 8th |
| 10 | France | 22.5% | 13th |
Nine of the 10 are in Europe. By the same data, the share of people aged 65 and over worldwide is 10.4%.
- How does the Top 10 change in 10 years?
| Rank | Country | Share of population 65+ in 2035 | Rank in 2025 |
|---|---|---|---|
| 1 | Japan | 32.7% | No. 1 |
| 2 | Italy | 31.3% | 2nd |
| 3 | Korea | 29.6% | 26th |
| 4 | Germany | 28.9% | 6th |
| 5 | Portugal | 28.9% | 3rd |
| 6 | Greece | 28.6% | 4th |
| 7 | Spain | 27.9% | 15th |
| 8 | Bosnia and Herzegovina | 27.4% | 9th |
| 9 | Austria | 26.9% | 19th |
| 10 | Croatia | 26.9% | 7th |
The biggest change is South Korea. It climbs 23 places, from 26th to 3rd. Its share of people aged 65 and over rises by more than 9 percentage points in ten years, the largest increase among the 156 countries. In 2035 South Korea has about 14.88 million people aged 65 and over. Spain (15th to 7th) and Austria (19th to 9th) also enter the list, while Finland, Serbia and France drop out.
- Why does growth slow in an aging country?
An economy grows from the number of people working and the amount each of them produces. When the number of people 65 and over rises and the working-age population shrinks, the whole country's output grows less even if productivity stays the same.
The International Monetary Fund (IMF) estimated that if current policies hold, world economic growth in 2025-2050 will be 1.1 percentage points lower than the 2016-2018 average, and that nearly three-quarters of that drop comes from demographic change. The Bank of Korea projected that South Korea's potential growth rate (the pace an economy can grow without stoking inflation) falls from 1.8% in 2025-2029 to 0.7% in 2040-2044 and 0.6% in 2045-2049.
Put simply, a shop where staff retire one by one and few new people join has a hard time growing sales even if the customers stay the same.
- Growth or welfare: what collides?
An aging country faces two pressures at once. Fewer people pay taxes and insurance contributions, while more people receive pensions and medical care. The IMF said many countries will need substantial fiscal effort after 2030 to keep their debt ratios from rising.
South Korea's National Pension reform shows this choice. The reform passed by the National Assembly on March 20, 2025 raises the contribution rate from 9% by 0.5 percentage points a year starting in 2026, reaching 13% in 2033, and sets the income replacement rate (pension as a share of average lifetime income) at 43%. Even by the projections made during the reform talks, the date the fund runs dry only moves back 9 years, from 2055 to 2064.
For a worker earning KRW 3 million a month (about $2,140), the contribution in 2033 rises from KRW 270,000 to KRW 390,000 (about $193 to $279), split half and half with the employer, so the worker's share goes from KRW 135,000 to KRW 195,000 (about $96 to $139). Protecting welfare means a heavier load on the working generation, and easing that load means smaller payments for retirees.
- Is there a way to keep growing while aging?
The IMF's answer is 'work healthier, work longer'. It estimated that the labor and experience of older people who stay this healthy could lift world growth by about 0.4 percentage points a year over 2025-2050.
The Bank of Korea likewise estimated that if structural reforms such as building an innovation ecosystem succeed, productivity gains could lift potential growth by 0.7 percentage points. A country cannot change how fast it ages, but it can change how it works.
- BITPRESS Insight
What to look for in an aging ranking is not today's position but how fast the share of people 65 and over is rising. Germany and France took close to 40 years to go from an aged to a super-aged society. South Korea took 7. It has to absorb the same change in far less time.
The faster the pace, the sooner the choice between growth and welfare arrives. The working generation's contributions, retirees' pensions and the country's growth rate all move at once.
When you read aging news, look at 'in how many years' rather than 'how many percent'. The faster a country ages, the sooner its contributions, pensions and growth rate change.
Sources
https://population.un.org/wpp/
https://www.imf.org/-/media/files/publications/weo/2025/april/english/ch2.pdf.md
https://www.imf.org/en/publications/weo/issues/2025/04/22/world-economic-outlook-april-2025/index.md
https://www.ajunews.com/view/20241219102429746
https://v.daum.net/v/20241224180002013
https://newsseoul.co.kr/news/view/1065606014003825
https://www.newsis.com/view/NISX20250314_0003099531
Glossary
Super-aged society — A society in which people aged 65 and over make up 20% or more of the population. By UN standards, 7% or more is called an aging society and 14% or more an aged society.
Medium variant — The UN's baseline population projection, which sets assumptions on fertility, lifespan and migration at their most likely values.
Potential growth — The pace at which a country can grow while using its labor and capital normally, without greatly stoking inflation.
Income replacement rate — The share of average lifetime income that a person who paid into the National Pension for 40 years receives as a pension.
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