The Bahá'í calendar, also called the Badí‘ calendar (badí‘ means wondrous or unique ), used by Bábism and the Bahá'í Faith, is a solar calendar with regular years of 365 days, and leap years of 366 days. Years are composed of 19 months of 19 days each, (361 days) plus an extra period of "Intercalary Days" (4 in regular and 5 in leap years). Years in the calendar begin at the vernal equinox, and are counted with the date notation of BE (Bahá'í Era), with 21 March 1844 CE being the first day of the first year. The period from 21 March 2012 to 20 March 2013 is the year 169 BE. At present, the Bahá'í calendar is synchronized to the Gregorian calendar, meaning that the extra day of a leap year occurs simultaneously in both calendars. Note: The Badi calendar was implemented during the Bábí faith and then adapted in the Bahá'í Faith.

The early version of the calendar begun to be implemented during the ministry of the Báb and his appointed successor Subh-i-Azal depended on the Báb's Persian Bayan and other works. It used a scheme of 19 months of 19 days (19x19) for a 361 day calendar and intercalary days assigned differently than the Baha'i implementation later. There is also a cycle of 19 years. William Miller's polemical work against the Bahá'í Faith claims that the date the calendar was to begin was 1850 CE though most sources agree the date was with the Declaration of the Bab to Mullá Husayn, May 23, 1844 CE. The beginning of the calendar year was with Nowruz. The calendar contains symbolic connections to prophecies of the Báb about the next Manifestation of God termed He whom God shall make manifest.

The Bahá'í Faith ( /bəˈhaɪ/) is a monotheistic religion founded by Bahá'u'lláh in 19th-century Persia, emphasizing the spiritual unity of all humankind. There are an estimated five to six million Bahá'ís around the world in more than 200 countries and territories.

In the Bahá'í Faith, religious history is seen to have unfolded through a series of divine messengers, each of whom established a religion that was suited to the needs of the time and the capacity of the people. These messengers have included Abraham, Moses, Jesus, and Muhammad - as well as figures from extra-Abrahamic traditions such as Zoroaster, Krishna, and the Buddha. For Baha'is, the most recent messengers are the Báb and Bahá'u'lláh. In Bahá'í belief, each consecutive messenger prophesied of messengers to follow, and Bahá'u'lláh's life and teachings fulfilled the end-time promises of previous scriptures. Humanity is understood to be in a process of collective evolution, and the need of the present time is for the gradual establishment of peace, justice and unity on a global scale.