The U.S. government estimates the total population at 40.2 million (July 2018 estimate). According to 2010 government statistics, the most recent available, 97 percent of the population is Muslim. Shia Muslims, predominantly Arabs but also including Turkoman, Faili (Shia) Kurds, and others, constitute 55 to 60 percent of the population, while Sunni Muslims are approximately 40 percent of the population. Of Sunnis, Sunni Kurds constitute 15 percent, Sunni Arabs 24 percent, and Sunni Turkomans the remaining 1 percent. Shia, although predominantly located in the south and east, are the majority in Baghdad and have communities in most parts of the country. Sunnis form the majority in the west, center, and north of the country.
Christian leaders estimate there are fewer than 250,000 Christians remaining in the country, with the largest population – at least 200,000 – living in the Ninewa Plain and the IKR. The Christian population has declined over the past 16 years from a pre-2002 population estimate of between 800,000 and 1.4 million persons. Approximately 67 percent of Christians are Chaldean Catholics (an Eastern Rite of the Roman Catholic Church), and nearly 20 percent are members of the Assyrian Church of the East. The remainder are Syriac Orthodox, Syriac Catholic, Armenian Catholic, Armenian Apostolic, and Anglican and other Protestants. There are approximately 2,000 registered members of evangelical Christian churches in the IKR, while an unknown number, mostly converts from Islam, practice the religion secretly.
Yezidi leaders report most of the 400,000 to 500,000 Yezidis in the country reside in the north, and approximately 360,000 remain displaced. Estimates of the size of the Sabean-Mandean community vary. According to Sabean-Mandean leaders, 10,000 remain in the country, mainly in the south with between 750 and 1,000 in the IKR and Baghdad. Baha’i leaders report fewer than 2,000 members, spread throughout the country in small groups, including approximately 500 in the IKR. The Shabak number between 350,000 and 400,000, three-fourths of whom are Shia and the rest Sunni; most are located in Ninewa. Armenian leaders report a population of approximately 7,000 Armenian Christians. According to Kaka’i (also known as Yarsani) activists, their community has approximately 120,000 to 150,000 members, traditionally located in the Ninewa Plain and in villages southeast of Kirkuk, as well as in Diyala and Erbil. The Jewish representative in the KRG Ministry of Endowment and Religious Affairs (MERA) reports 70 to 80 Jewish families reside in the IKR, though he noted that some Jewish families do not openly acknowledge their religion for fear of persecution. According to a Baghdad Jewish community leader, there are fewer than six adult members of the local Jewish community.
According to the International Organization for Migration (IOM), as of December, nearly 1.8 million persons remained displaced within the country. Population movements are multi-directional, with some persons fleeing their homes and others returning home. According to the IOM, as of May, approximately 67 percent of the Internally Displaced Persons (IDP) population were Arab Sunni, 13 percent Kurdish Sunni, 8 percent Yezidi, 6 percent Turkoman Shia, 2 percent Arab Shia, 1 percent either Syriac, Chaldean, or Assyrian Christian, 2 percent Shabak Shia, and less than 1 percent Turkoman Sunni, Shabak Sunni, or Kurdish Shia.