There are an estimated 1.6 billion Muslims around the world, making Islam the world’s second-largest religious tradition after Christianity, according to the December 2012 Global Religious Landscape report from the Pew Research Center’s Forum on Religion & Public Life.
Although many people, especially in the United States, may associate Islam with countries in the Middle East or North Africa, nearly two-thirds (62%) of Muslims live in the Asia-Pacific region, according to the Pew Research analysis. In fact, more Muslims live in India and Pakistan (344 million combined) than in the entire Middle East-North Africa region (317 million).
However, the Middle East-North Africa region has the highest concentration Muslims of any region of the world: 93% of its approximately 341 million inhabitants are Muslim, compared with 30% in sub-Saharan Africa and 24% in the Asia-Pacific region.
Muslims make up a majority of the population in 49 countries around the world. The country with the largest number (about 209 million) is Indonesia, where 87.2% of the population identifies as Muslim. India has the world’s second-largest Muslim population in raw numbers (roughly 176 million) though Muslims make up just 14.4% of India’s total population.
Pew Research uses an array of surveys, census reports, population registers and other data sources to estimate numbers of Muslims and other religious groups around the world, the goal being to count all groups and people who self-identify with a particular religion. The figures presented here are as of 2010.
Pew Research has put out several major reports recently on Muslims around the world, including ones on differences in their religious beliefs and practices, their views of religion, politics and society, and their use of the internet. For more details on the geographic distribution of the Muslim population, here is the relevant chapter of the Global Religious Landscape report. You can also explore our data on the current Muslim population in each country here and projections for future population growth here.