The Bahá'í Calendar Has Nineteen Months of Nineteen Days

The Báb, founder of the Bábí movement that became the seed of the Bahá'í faith, designed a new calendar in 1844 for his followers. He kept it strict and arithmetical: 19 months of 19 days each. The number 19 had theological weight, tied to the Báb's first 18 disciples plus himself, the Letters of the Living. Multiplying out, 19 × 19 = 361 days. A solar year is about 365.24. The shortfall is dealt with by Ayyám-i-Há — 'days of Há,' an intercalary period of four ordinary days, or five in a leap year, inserted between the 18th and 19th months. The 19th month, ʿAlá, is then the month of fasting. Sundown to sundown, no food or drink, for 19 days.

The months, like the days of the week, are named for divine attributes: Bahá (splendor), Jalál (glory), Jamál (beauty), and so on, ending with ʿAlá (loftiness). The week has seven days and starts on Saturday. The day starts at sunset. Year 1 begins at the spring equinox of 1844, the year the Báb declared his mission.

Bahá'u'lláh confirmed the calendar in the Kitáb-i-Aqdas, the central book of Bahá'í law, written around 1873. For most of the calendar's history, Bahá'í communities calculated New Year by reference to the equinox visible at the meridian of Tehran — a religiously significant location, since Bahá'u'lláh was born there. In 2014, the Universal House of Justice clarified the rule globally: Naw-Rúz, the new year, is the sunset before the equinox at the meridian of Tehran, with the equinox calculated astronomically, no longer observed.

The result is a calendar that runs steady against the seasons, costs nineteen days a year to fasting, and hides four extra days in a slot named after a single Arabic letter.