The number of Muslims worldwide increased more rapidly than any other major religious group between 2010 and 2020, according to a Pew Research Center analysis of global census and survey data.
The study found that the global Muslim population grew by 347 million people during the decade, more than all other religious groups combined. This increase brought the total to approximately 1.9 billion and raised Islam’s share of the world’s population by 1.8 percentage points, to 25.6 percent.
Islam’s growth is largely attributed to demographic factors, including high fertility rates and a youthful age structure in many Muslim-majority countries. A significant portion of the global Muslim population lives in regions with rapid natural population growth, such as sub-Saharan Africa and the Middle East-North Africa region.
The majority of Muslims, about 59 percent, live in the Asia-Pacific region, which includes populous countries such as Indonesia, Pakistan, India and Bangladesh. Sub-Saharan Africa is home to another substantial portion, contributing to the religion’s youthful demographic profile. As of 2020, 33 percent of Muslims globally were under the age of 15, the highest proportion of children among all major religious groups studied.
While religious switching — when individuals change or leave their religion — has significantly impacted other groups, particularly Christians, such shifts have had little overall effect on the Muslim population. Pew’s analysis indicates that switching into or out of Islam remains relatively uncommon worldwide.
In contrast, Christians, while still the largest religious group at 2.3 billion, saw slower growth relative to the global population. Christianity’s share declined by 1.8 percentage points, to 28.8 percent. Most of the losses were due to religious disaffiliation, particularly in North America and Europe.
Geographically, the growth of the Muslim population was not evenly distributed. Only a few countries, including Kazakhstan, Benin and Lebanon, saw their Muslim share increase by at least five percentage points. Declines occurred in countries such as Tanzania and Oman. Despite limited national-level shifts, the global increase was driven primarily by population growth in countries where Muslims already constitute a significant share.
Overall, Pew estimates that 75.8 percent of the world’s population identified with a religion in 2020, down slightly from 76.7 percent in 2010. Muslims and the religiously unaffiliated — whose numbers rose by 270 million over the decade — were the only two major groups to grow as a share of the global population.
The findings are part of Pew’s ongoing Global Religious Futures project, which analyzes religious change and its social implications through extensive demographic and survey data.