Why the Global Buddhist Population Declined Between 2010 and 2020

Between 2010 and 2020, something historically unusual happened in the global religious landscape: Buddhists became the only major religious group in the world whose population declined.

According to a Pew Research Center analysis covering 201 countries and territories, the number of people worldwide who identified as Buddhist fell from approximately 343 million in 2010 to 324 million in 2020. That’s a decline of about 5% over the decade.

This drop stands in sharp contrast to broader global trends. During the same period, the world’s population grew by 12%, and all other major religious groups tracked globally increased in size. As a result, Buddhists’ share of the global population declined from 4.9% in 2010 to 4.1% in 2020.

So what explains this shift?

An Aging Population With Fewer Children

One of the most important factors is demographic.

Buddhists are, on average, older than members of any other major religious group studied. As of 2020, the global median age of Buddhists was about 40 years old. By comparison:

• The global median age overall was 31

• Jews had a median age of 38

• Christians: 31

• Hindus: 29

• Muslims: 24

Age matters because it directly affects population growth. Older populations tend to have fewer births and more deaths.

In addition, Buddhists have lower fertility rates than other major religious groups. Between 2010 and 2015, Buddhists were estimated to have about 1.6 children per woman. That’s roughly one child fewer than the global average fertility rate and well below the replacement-level fertility rate of 2.1 children per woman—the minimum typically needed for a population to maintain its size without immigration or religious conversion.

Notably, Buddhism was the only religion in the analysis whose global fertility rate during that period fell below replacement level.

Over time, sustained low fertility reshapes a population’s age structure. Instead of a pyramid with many young people at the base and fewer elderly at the top, the structure becomes more like a rectangle—or even an inverted pyramid—with a growing share of older adults and relatively few children. Initially, growth slows. Eventually, decline sets in.

Geography Matters: The East Asia Effect

Demographics alone don’t tell the whole story. Geography plays a crucial role.

Nearly all Buddhists—98%—live in the Asia-Pacific region. Around 40% live in just five East Asian places: China, Japan, South Korea, Taiwan, and Hong Kong.

East Asia is one of the oldest regions in the world demographically. Median ages are high, birth rates are low, and religious affiliation patterns have shifted significantly over time.

Between 2010 and 2020, the total number of Buddhists in those five East Asian places fell by 32 million—a 22% decline. Meanwhile:

• The combined populations of those five places grew by just 5%

• The rest of the Asia-Pacific region grew by 13%

• The rest of the world’s population grew by 16%

This means Buddhism’s demographic base is concentrated in parts of the world that are aging rapidly and experiencing slow population growth.

The Role of Religious Switching

Another key factor is religious switching—the process by which individuals change from the religion in which they were raised to a different religious identity (or no religion) in adulthood.

Globally, Buddhism does attract converts. For every 100 adults who were raised Buddhist, 12 have joined the religion. In proportional terms, Buddhism gains more converts than Christianity, Hinduism, or Islam.

However, it also loses a higher share of adherents than any other major world religion studied. For every 100 adults raised Buddhist, 22 have left the religion—either identifying with another religion or with no religion at all.

The net effect is a loss of 10 adherents for every 100 people raised Buddhist.

This dynamic is especially pronounced in East Asia:

• In Japan, roughly half of adults raised Buddhist have left the religion.

• In South Korea, about six-in-ten have left.

• In contrast, in Thailand—which has the world’s largest Buddhist population—nearly all adults raised Buddhist still identify as Buddhist today.

  
  

These regional differences show that religious switching is not uniform across the Buddhist world. It is heavily concentrated in certain East Asian societies.

A Convergence of Forces

The decline in the global Buddhist population between 2010 and 2020 is not the result of a single cause. Rather, it reflects the convergence of multiple demographic and social forces:

• An aging population

• Fertility rates below replacement level

• Concentration in low-growth regions

• Net losses through religious switching

  
  

Together, these dynamics help explain why Buddhism—despite its long history, global influence, and continued appeal to converts—was the only major religion to shrink in absolute numbers during that decade.

Looking ahead, whether this trend continues will likely depend on demographic shifts in Asia, patterns of religious identity among younger generations, and the evolving role of Buddhism in rapidly changing societies.