The U.S. government estimates the population at 82.8 million (July 2016 estimate). According to U.S. government estimates and other statistical reports, including Global Security and Iran Press Watch, Muslims constitute 99 percent of the population; 89-94 percent are Shia and 5-9 percent Sunni (mostly Turkmen, Arabs, Baluchis, and Kurds living in the northeast, southwest, southeast, and northwest, respectively). Afghan refugees, economic migrants, and displaced persons also make up a significant Sunni population but accurate statistics on the breakdown between Sunni and Shia are unavailable. There are no official statistics available on the number of Muslims who practice Sufism, although unofficial reports estimate several million.
According to U.S. government estimates and other statistical estimates, including Global Security, Iran Press Watch, and Iran Primer, groups together constituting the remaining less than 1 percent of the population include Bahais, Christians, Jews, Sabean-Mandaeans, Zoroastrians, and Yarsanis. The three largest non-Muslim minorities are Bahais, Christians, and Yarsanis.
There is no official count of Yarsanis, but one NGO and some Yarsani leaders estimate there are up to one million. Yarsanis have often been classified by the government as Shia Muslims practicing Sufism, but Yarsanis identify Yarsan as a distinct faith (known as Alhe Haq or Kakai). Yarsanis are mainly located in Loristan and the Kurdish regions.
According to Human Rights Watch data, Bahais number at least 300,000.
According to World Christian Database statistics, there are approximately 285,000 Christians, although some estimates suggest there may be many more Christians than actually reported. While the government’s Statistical Center of Iran reports there are 117,700, Elam Ministries, an Iranian Christian organization, estimates that there could be between 300,000 and one million Christians. The majority of Christians are ethnic Armenians concentrated in Tehran and Isfahan. Estimates by the Assyrian Church of the total Assyrian and Chaldean Christian population put their combined number at 7,000. There are also Protestant denominations, including evangelical groups, but there are no authoritative data on their numbers. Christian groups outside the country estimate the size of the Protestant community to be less than 10,000, although many Protestants and other converts to Christianity from Islam reportedly practice in secret.
According to Zoroastrian groups and the Statistical Center of Iran, there are approximately 25,000 Zoroastrians.
According to the Tehran Jewish Committee, there are approximately 9,000 Jews, while one British media report estimated their number at 18,000-20,000. There reportedly are 5,000 to 10,000 Sabean-Mandaeans.