The Bahá’í calendar, known as the Badí‘ calendar, was introduced by the Báb. Bahá’u’lláh confirmed and adopted this calendar, fixing its commencement at the year of the Báb’s declaration in 1844.

In a messageThe Universal House of Justice, 10 July 2014 regarding the universal implementation of the Badí‘ calendar, the Universal House of Justice states:

“The adoption of a new calendar in each dispensation is a symbol of the power of Divine Revelation to reshape human perception of material, social, and spiritual reality. Through it, sacred moments are distinguished, humanity’s place in time and space reimagined, and the rhythm of life recast.”

As the Bahá’í Era (designated B.E.) was inaugurated by twin Founders, the Bahá’í Holy Days include events related to the birth, declaration, and passing of both Bahá’u’lláh and the Báb.

This calendar consists of 19 months of 19 days each, with the addition of intercalary days known as Ayyám-i-Há. The number of these intercalary days varies according to the timing of the vernal equinox in the northern hemisphere in successive years.

The Báb named each of the 19 months, listed below, after certain attributes of God. The Bahá’í New Year (Naw-Rúz) is astronomically fixed, coinciding with the vernal equinox. Holy Days are fixed within the solar calendar, except for the observance of the Festival of the Twin Birthdays—the Birth of the Báb and the Birth of Bahá’u’lláh—which moves year to year, taking place on the first and the second day following the occurrence of the eighth new moon after Naw-Rúz.

According to the Bahá’í calendar, a day is the period from sunset to sunset; consequently, the day on which a Nineteen Day Feast, Holy Day, or other significant dates are observed begins at sunset on the eve of each corresponding Gregorian calendar date shown below. For example, if Naw-Rúz falls on 21 March, it is marked from sunset on 20 March to sunset on 21 March.