The number of people identifying as Buddhist worldwide fell over the past decade, with researchers pointing to an ageing population and a growing trend of people abandoning the religion in adulthood.
A major new analysis by the Pew Research Center found that Buddhism was the only major world faith to record a decline between 2010 and 2020.
During that period, the number of Buddhists worldwide dropped from around 343 million to 324 million – a fall of about 5% – even as the global population expanded by roughly 12%.
This meant Buddhists made up a smaller proportion of the global population, falling from 4.9% to 4.1%.
Researchers say the change reflects a combination of demographic pressures and religious switching, with more people leaving Buddhism than adopting it.
While Buddhism continues to attract converts, it loses a greater proportion of those raised within the tradition than any other major faith examined in the study.
According to Pew’s analysis, for every 100 adults brought up as Buddhists, 12 adopt the religion as converts. Conversely though, for every 12 who join as adult converts, 22 leave it in adulthood, describing themselves instead as believers of another faith or as having no religious affiliation. This produces a net loss of 10 followers for every 100 people brought up in the faith.
The pattern is particularly visible in parts of East Asia. The Center’s 2024 surveys suggest that about half of adults raised Buddhist in Japan no longer identify with the religion, while in South Korea 60% have moved away from it.
In contrast, switching is far less common in countries such as Thailand - the country with the biggest Buddhist population in the world - where most people raised in the faith continue to identify with it.
Demographic factors are also playing a major role. Globally, Buddhists tend to be older than members of most other major religious groups. The median age of Buddhists by 2020 was around 40, compared with 31 for the global population overall. Other major faith groups were generally younger, including Christians (31), Jews (38), Muslims (24) and Hindus (29).
Fertility rates among Buddhists are also significantly lower than the global average. Women who identify as Buddhist have an estimated 1.6 children on average - the only group whose fertility rate was well below the replacement level of 2.1 needed for a population to remain stable over time.
Researchers say that when birth rates stay low for long periods, the population structure gradually shifts toward older generations, eventually leading to decline.
Geography further shapes the trend, with 98% of the world’s Buddhists residing in the Asia-Pacific region, and about 40% concentrated in East Asia – particularly in South Korea, China, Japan, Hong Kong and Taiwan.
These societies already have some of the world’s oldest populations and lowest birth rates.
The number of Buddhists between 2010 and 2020 in those five places alone decreased by 32 million – a decline of roughly 22%.
The findings form part of broader research by the Pew Research Center examining global religious change.
Across many regions, researchers say religious affiliation is becoming more fluid, with rising numbers of people identifying as atheist, agnostic or having “no religion”.
In several countries, including the United Kingdom, Christianity has also lost its majority status as unaffiliated populations grow.
By 2020, 10 countries worldwide had populations in which the religiously unaffiliated formed the largest group.
Yet the wider global picture is more complex than simple decline.
Separate research conducted by Gallup on behalf of the British and Foreign Bible Society and United Bible Societies found that, in most parts of the world, most people continue to believe in God or some form of higher power, and in 5 of the 7 global contexts studied, majority said that faith plays a significant role in daily life.
Taken together, the findings suggest that while institutional affiliation is weakening in some countries, religion continues to play a significant role globally.
Christianity remains the world’s largest religious community, Muslims are the fastest-growing major faith group, and most countries still have clear religious majorities.
The data also suggests that patterns of belief are increasingly shaped not only by birth rates but also by personal choice as growing numbers of people reassess the religious identities they inherited in childhood.
