World religions statistics place the Bahá'í Faith around 0.1% of the world population in recent years. The World Christian Encyclopedia estimated only 7.1 million Bahá'ís in the world in 2000, representing 218 countries, and its evolution to the World Christian Database (WCD) estimated 7.3 million in 2010 while accredited through the Association of Religion Data Archives (ARDA). However the WCD stated: "The Baha'i Faith is the only religion to have grown faster in every United Nations region over the past 100 years than the general population; Baha'i [sic] was thus the fastest-growing religion between 1910 and 2010, growing at least twice as fast as the population of almost every UN region." This source's only documented flaw was to consistently have a higher estimate of Christians than in other cross-national data sets 2015's estimate is of 7.8 million Bahá'ís in the world.
From its origins in the Persian and Ottoman empires of the 19th century the Bahá'í Faith was able to gain converts elsewhere in Asia, Europe, and North America by the early 20th century. John Esslemont performed the first review of the worldwide progress of the religion in 1919. 'Abdu'l-Bahá, son of the founder of the religion, then set goals for the community through his Tablets of the Divine Plan shortly before his death. Shoghi Effendi then initiated systematic pioneering efforts that brought the religion to almost every country and territory of the world and converts from more than 2000 tribes and peoples. There were serious setbacks in the Soviet Union where Bahá'í communities in 38 cities across Soviet territories ceased to exist. However plans continued building to 1953 when the Bahá'ís initiated a Ten Year Crusade after plans had focused on Latin America and Europe after WWII. That last stage was largely towards parts of Africa. Wide-scale growth in the religion across Sub-Saharan Africa particularly was observed to begin in the 1950s and extend in the 1960s.
There was diplomatic pressure from northern Arab countries against this development that was eventually overcome. Starting in the 1980s with Perestroyka the Bahá'ís began to re-organize across the Soviet Union and Eastern Bloc. While sometimes failing to meet official minimums for recognitions as a religion, communities of Bahá'ís do exist from Poland to Mongolia. The worldwide progress was such that the Encyclopædia Britannica (2002) identified the religion as the second-most geographically widespread religion after Christianity. It has established Bahá'í Houses of Worship by continental region and been the object of interest and support of diverse non-Bahá'í notable people from Leo Tolstoy to Khalil Gibran to Mohandas K. Gandhi to Desmond Tutu. See List of Bahá'ís for a list of notable Bahá'ís.
ARDA/WCD statistics place the Bahá'í Faith as currently the largest religious minority in Iran (despite significant persecution and the overall Iranian diaspora), Panama, and Belize; the second largest international religion in Bolivia, Zambia, and Papua New Guinea; and the third largest international religion in Chad and Kenya. In 2014 the religion was officially recognized in Indonesia and in addition to various countries it is the second largest religion in state of South Carolina – a fact that, despite its small size, got some attention in 2014. Based on data from 2010, Bahá'ís were the largest minority religion in 80 counties out of the 3143 counties in the United States. The countries with the fastest annual growth from 2000 to 2015 per annum, where a country has over 100,000 people, were, (starting with the fastest): Qatar, UAE, Bahrain, Oman, Kuwait, Kazakhstan, Western Sahara, South Sudan, and Niger, ranging from 3.90% growth per year up to 9.56%.
A Bahá'í published survey reported 4.74 million Bahá'ís in 1987.
Bahá'í sources since 1991 usually estimate the worldwide Bahá'í population at "above 5 million".