Adherents of Islam constitute the world's second largest and fastest growing major religious grouping, maintaining suggested 2017 projections in 2022. As of 2020, Pew Research Center (PEW) projections suggest there are a total of 2 billion adherents worldwide, representing 25.6% of the world population. Further studies indicate that the global spread and percentage growth of Islam is primarily due to relatively high birth rates and a youthful age structure."The Future of Global Muslim Population: Projections from 2010 to 2013" Accessed July 2013. Conversion to Islam does not have much impact on the overall growth of the Muslim population, as the number of people converting to Islam is roughly equal to the number of those leaving the faith. According to another study published in 2015 by PEW, Islam is expected to experience a modest gain of 3 million adherents through religious conversion between 2010 and 2050, although this modest impact will make Islam, compared with other religions, the second largest religion in terms of net gains through religious conversion after religiously unaffiliated."Cumulative Change Due to Religious Switching, 2010–2050, p.43"

Most Muslims fall under either of three main branches:

Sunni (85–90%, roughly 1.7–1.8 billion people)*

Who Gets To Narrate the World "The Sunnis (approximately 80%)" A world theology N. Ross Reat "80% being the Sunni" Islam and the Kadiyani jama'at "The Sunni segment, accounting for at least 80% of the worlds Muslim population" Shia (10–15%, roughly 200–300 million people)See Ibadi (0.16–0.37%, roughly 3–7 million people)

In 2020, there were 53 Muslim-majority countries. Islam is the majority religion in several subregions: Central Asia, West Asia, Southeast Asia, North Africa, West Africa, the Sahel, and the Middle East.Encyclopædia Britannica. Britannica Book of the Year 2003. Encyclopædia Britannica, (2003) p.306 According to the Encyclopædia Britannica, as of mid-2002, there were 376,453,000 Christians, 329,869,000 Muslims and 98,734,000 people who practiced traditional religions in Africa. Ian S. Markham, (A World Religions Reader. Cambridge, MA: Blackwell Publishers, 1996.) is cited by Morehouse University as giving the mid-1990s figure of 278,250,800 Muslims in Africa, but still as 40.8% of the total population. These numbers are estimates, and remain a matter of conjecture. See Amadu Jacky Kaba. The spread of Christianity and Islam in Africa: a survey and analysis of the numbers and percentages of Christians, Muslims and those who practice indigenous religions. The Western Journal of Black Studies, Vol 29, Number 2, June 2005. Discusses the estimations of various almanacs and encyclopedium, placing Britannica's estimate as the most agreed figure. Notes the figure presented at the World Christian Encyclopedia, summarized here, as being an outlier. On rates of growth, Islam and Pentecostal Christianity are highest, see: The List: The World's Fastest-Growing Religions , Foreign Policy, May 2007.Britannica , Think Quest , Wadsworth.com

The diverse Asia-Pacific region contains the highest number of Muslims in the world, surpassing the combined Middle East and North Africa (MENA). Around 62% of the world's Muslims live in the Asia-Pacific region (from Turkey to Indonesia), with over one billion adherents. Asia hosts the world's four largest domestic populations, starting with Indonesia at 12.7% of the world, followed by Pakistan (11.1%), then India (10.9%), and Bangladesh (9.2%).

Africa has the 5th and 6th largest populations in Nigeria (5.3%) and Egypt (4.9%). The Middle East hosts 7th and 8th with both Iran and Turkey holding an estimated 4.6%. Only about 20% of Muslims live in the Arab world.See: Esposito (2002b), p.21 Esposito (2004), pp.2,43

Regional comparisons South Asia has the largest population of Muslims in the world, with about one-third of all Muslims being from South Asia. Islam is the dominant religion in the Maldives, Afghanistan, Pakistan, and Bangladesh. India is the country with the largest Muslim population outside Muslim-majority countries with more than 200 million adherents.

The Middle East-North Africa (MENA) region hosts 23% of the world's Muslims, and Islam is the dominant religion in every country in the region other than Israel and Cyprus.

The country with the single largest population of Muslims is Indonesia in Southeast Asia, which on its own hosts 13% of the world's Muslims. Together, the Muslims in the countries of Southeast Asia constitute the world's third-largest population of Muslims. In the countries of the Malay Archipelago, Muslims are in the majority in Brunei, Indonesia, and Malaysia.

About 15% of Muslims reside in Sub-Saharan Africa, and sizeable Muslim communities are also found in the Americas, Russia, China and Europe.

Western Europe hosts many Muslim immigrant communities where Islam is the second-largest religion after Christianity, where it represents 6% of the total population or 24 million people.See: Esposito (2004) pp.2,43

Denominations

Islam is divided into two major denominations, Sunni and Shia. Of the total Muslim population, 87–90% are Sunni and 10–13% are Shi'a. Most Shias (between 68% and 80%) live in mainly four countries: Iran, Azerbaijan, Bahrain, and Iraq. Furthermore, there are concentrated Shi'a populations in Lebanon, Russia, China, Pakistan, Bangladesh, and 10 sub-Saharan African countries. The major surviving Imamah-Muslim Sects are Usulism (with around 8.5% of the total Muslim population), Nizari Ismailism (with around 1%) and Alevism (with slightly more than 0.5%According to David Shankland, 15% of Turkey's population. in Structure and Function in Turkish Society. Isis Press, 2006, p. 81. but less than 1%According to Krisztina Kehl-Bodrogi, Syncretistic Religious Communities in the Near East edited by her, B. Kellner-Heinkele, & A. Otter-Beaujean. Leiden: Brill, 1997.). The other existing groups include Zaydis of Yemen whose population is around 0.5% of the world's Muslim population, Musta'li Ismaili (with nearly 0.1% whose Tayyibi adherents reside in Sindh and Gujarat in South Asia. There are also significant diaspora populations in Europe, North America, the Far East, and East Africa), and Ibadis from the Kharijites whose population has diminished to a level below 0.15%. (with around 1%), non-denominational Muslims, Quranist Muslims and Wahhabis (with around 1–2%Destined Encounters – Page 203, Sury Pullat – 2014 of the world's total Muslim population) also exist.

A study from the Pew Research Center (PEW) in 2012 found that many Muslims (one out of five in 22 Muslim majority countries) identify as non-denominational or "just a Muslim". This non-denominational affiliation is most common in Southern and Eastern Europe as well as Central Asia, with minority populations in Southeast Asia and sub-Saharan Africa. The study found that a median percentage of 74% of Muslims in Kazakhstan, 65% in Albania, 64% in Kyrgyzstan, 56% in Indonesia, 55% in Mali, and 40% in Cameroon identify this way. However, it is much less common in parts of Africa, the Middle East, and South Asia.

Countries

As of 2020, there were 53 Muslim-majority countries, which was the same number as in 2010. Most of the percentages of Muslim populations of each country shown below, if not stated otherwise, were taken from the study by the Pew Research Center (PEW) report of 5 facts about the Muslim population in Europe, 2017.

Table