Ranked: Where Senior Populations Will Grow Fastest by 2040Key TakeawaysCountries with relatively young populations today are projected to see the fastest growth in residents aged 65 and older through 2040.Saudi Arabia leads the selected economies with projected senior population growth of 115%, followed by the UAE at 80%.Japan ranks near the bottom at 7% because it already has one of the world’s oldest populations.Population aging is accelerating, but not where many people might expect.While countries like Japan already have large older populations, much of the fastest growth is projected to occur in younger economies such as Saudi Arabia, Malaysia, and Vietnam. Falling fertility rates and rising life expectancy are rapidly reshaping their age structures.Based on World Economic Forum analysis of the UN’s World Population Prospects 2024, this graphic compares projected growth in the population aged 65 and older across 21 selected economies between 2025 and 2040.The Fastest Growth Is Happening in Younger CountriesSaudi Arabia has the fastest growth in its senior population, followed by the UAE, Malaysia, and Vietnam. Each is projected to see growth of at least 77% through 2040.Below we list the 21 select countries, growth in their 65-and-older population, and the current median age:CountryProjected Increase (2025–2040F)Median Age 2025 Saudi Arabia115%29.6 UAE80%31.6 Malaysia78%31.0 Vietnam77%33.4 Colombia77%32.5 Indonesia75%30.4 Mexico74%29.6 China69%40.1 India68%28.8 Singapore59%36.2 Brazil59%34.8 Nigeria58%18.1 South Korea58%45.6 Thailand55%40.6 Canada32%40.6 Netherlands28%41.5 U.S.28%38.5 UK26%40.1 France22%42.3 Croatia7%45.3 Japan7%49.8 World Average53%30.9Looking at median age reveals the story behind the data. Many countries with relatively young populations are entering the early stages of population aging, leading to rapid growth in their 65-and-older populations. By contrast, older societies such as Japan have already undergone much of this demographic shift.Diverging Trends in GrowthSaudi Arabia has a median age of roughly 30, yet its senior population is projected to more than double over the next 15 years. Nigeria, which has a median age of just 18, is also expected to see its senior population grow by nearly 60%.The same trend is emerging across Africa. Although it remains the world’s youngest continent, its older population is projected to reach 235 million by 2050, exceeding North America’s total.Japan presents the opposite picture. Its median age is approaching 50, but its senior population is projected to grow by just 7%, largely because older adults already account for such a significant share of the population.Globally, the population aged 65 and older is projected to grow by 53% through 2040. This exceeds the projected increases in the U.S. (28%), the UK (26%), Canada (32%), and China (40%).Why Younger Countries Are Aging FasterRapid growth in a country’s senior population does not necessarily mean it will become one of the world’s oldest societies. Instead, it shows how quickly the country’s age structure is changing.Many younger economies are experiencing declining fertility rates as life expectancy continues to rise. At the same time, large working-age generations are moving toward retirement, causing the number of older adults to increase rapidly from a relatively small base.Older societies went through this transition decades earlier. Countries such as Japan now have slower senior population growth not because aging has stopped, but because much of the demographic shift has already occurred.Learn More on the Voronoi App To learn more about this topic, check out this graphic on the countries with the biggest gains in life expectancy since 1965.