South Korea's population could plummet to just 7.53mn by 2125 under the worst-case scenario, representing an 85% decline from current levels, according to research published by the Korean Peninsula Population Institute for Future, Yonhap reported on July 2.

East Asian countries are currently leading the world in population decline; however, European, Middle Eastern and other regions are also seeing declines, with governments across the world working to try to turn the tide in declining native populations. 

The Seoul-based think-tank used cohort component methodology to project demographic trends over the next century, incorporating birth rates, mortality rates and immigration patterns. Even under the most optimistic projection, the population is set to shrink to 15.73mn by 2125, less than one-third of the current 51.68mn.

The median projection estimates South Korea's population at 11.15mn by 2125, which would be smaller than Seoul's current population of 9.3mn. The study forecasts a 30% population decline by 2075, followed by a more than 50% drop over the subsequent 50 years.

South Korea's demographic structure is expected to transform from a "stingray" shape with a broad base of younger people to a "cobra" formation by 2125, with narrowing bands across all age groups and a population heavily skewed towards older demographics.

The aging crisis in Korea will intensify dramatically, with projections showing 140 seniors aged 65 or older for every 100 working-age individuals by 2100. Currently, 100 working-age people support approximately 30 seniors, indicating South Korea is moving towards an "inverted pyramid" society where dependents outnumber those providing support.

The institute analysed 60,000 posts from workplace community app Blind to gauge social sentiment amongst people in their 20s to 40s regarding marriage and childbirth.

The research revealed younger generations now prioritise "money" and "housing" over "love" when discussing marriage, with financial burdens consistently emerging as the dominant concern regarding childbirth.

 

South Korea's total fertility rate stood at 0.75 in 2024, well below the replacement level of 2.1 children per woman.

The total fertility rate (TFR) fell to 0.72 children per woman in 2025, marking the lowest figure globally, according to newly released demographic data. The number of births in South Korea dropped to 224,835 in 2025, a decrease of 2.2% compared to the previous year.

Japan also reported a record low TFR of 1.15 in 2025, with births declining to 730,000 from 753,000 in 2024. The country’s fertility rate has consistently remained below the replacement level of 2.1 children per woman, contributing to ongoing population decline.

Meanwhile, China’s TFR was recorded at 1.10 in 2025, down from 1.11 in 2024, with 7.65mn births compared to 7.85mn the previous year. The sustained low fertility rate in China has raised concerns among policymakers about long-term demographic and economic challenges.

Taiwan was the only territory in East Asia to report an increase in TFR, rising from 1.22 in 2024 to 1.27 in 2025. Births in Taiwan climbed to 140,000 in 2025, up 3.7% from 135,000 in 2024.

Special economic zones of Hong Kong and Macao continued to register some of the lowest fertility rates in the region, with TFRs of 0.77 and 0.88, respectively in 2025. Hong Kong recorded 33,000 births, a 5.7% decrease from the previous year, while Macao’s births fell by 9% to 4,550.

Interestingly, Mongolia stood out as the only East Asian country with a TFR near the replacement level, recording 2.12 in 2025. However, births in Mongolia also declined by 2.9% to 68,000.

Elsewhere, Ukraine was the country losing population the fastest in 2023 due to the conflict with Russia. Conflict can be a powerful force in changing a country's demographics by creating refugees, but also casualties.

Which countries lose population the fastest also tells a story of economic stagnation, isolation and emigration for many, while low birth rates and ageing populations play yet another role in driving down the number of residents in many countries, Statista reported earlier this year.