Zoroastrian Calendar
The three Zoroastrian calendars
Understanding the history behind our date recordings
Adherents of Zoroastrianism use three distinct versions of traditional calendars , all derived from medieval Iranian calendars and ultimately based on the Babylonian calendar as used in the Achaemenid empire.
01
The Shenshai Calendar
In the Shenshai calendar, a year consists of 12 months, or mahs, and each month has 30 days. Each of these days is known as a roj, and each roj has a name. As 30 days * 12 months = 360 days, there are an additional 5 days (gathas) added to the 12th month to make a 365 day year.
A solar calendar, however, is around 365 1/4 days, which the Gregorian calendar accommodates by adding a day every four years (leap day). Because of this difference, the Zoroastrian calendar and solar year began to diverge. In 1006 C.E. the Zoroastrian calendar and solar year once again aligned, resulting in Navroze occuring on the Vernal Equinox. It was then decided that an extra month was to be added every 120 years to accommodate for the difference between the solar year and the Zoroastrian calendar year.
The Zoroastrians in India (Parsis) last remembered to add this extra month in 1129 C.E. Consequently, New Year, which originally correlated with the vernal equinox on March 21st, has since fallen earlier in the Gregorian calendar year such that it now occurs in August.
02
The Kadmi Calendar
While the Zoroastrians in India intercalated an extra month to the calendar around 1129 C.E., the Zoroastrians in Iran did not, causing the calendar used by the Iranian Zoroastrians to be ahead by a month. This discrepency was brought to the attention of the Indian Zoroastrians by a visiting Iranian priest in the 1700s. A group of Indian Zoroastrians (the Kadmi or Qadimi) decided to follow the Iranian calendar, believing it to be more authentic.
03
The Fasli Calendar
In the early twentieth century, Khurshedji Cama devised the Fasli Calendar, which maintained alignment with the seasons such that New Year's day coincides with the vernal equinox. Similar to the Shenshai and Kadmi calendars, it consists of 12 months of 30 days with an additional 5 days (gathas), but intercalates a leap day called Avardad-sal-Gah every four years (patterned after the Gregorian calendar's leap day).