The First Day begins at sunset on Saturday of the Gregorian calendar.
MONTHS
Each month begins on the day when the first sliver of moon becomes visible after the dark of the moon.
There are typically 12 months in a year, with a 13th month added for leap years:
Nissan
Iyar
Sivan
Tammuz
Av
Elul
Tishri
Cheshvan
Kislev
Tevet
Sh’vat
Adar (or Adar I in leap years)
Adar II in leap years only
The first month begins around March-April on the Gregorian calendar.
YEARS
Each numbered year begins on 1 Tishri (first day of the seventh month), which is also the first day of the Jewish festival of Rosh Hashana.
The date of 1 Tishri occurs a pre-calculated number of days after the previous Rosh Hashana. The calculation is based on four rules that set the timing on or shortly after the new moon.
To determine the numbered year of the Jewish calendar, add 3,760 to the year of the Gregorian calendar if before 1 Tishri; add 3,761 if after 1 Tishri.
APPOINTED TIMES
Each appointed time begins as follows:
Tu B’Shvat Purim Pesach Yom Hashoah Yom Hazikaron Yom Ha’atzmaut Lag B’Omer Yom Yerushalayim Shavuot Tisha B’Av Tu B’Av Rosh Hashanah Yom Kippur Sukkot Shemini Atzeret Simchat Torah Chanukah
