How does the Jewish calendar
differ from the secular calendar?
The Jewish calendar is based on both lunar and solar
cycles. It calculates the year of creation at 3761 BCE.
The Jewish calendar is Israel's official calendar and
all the Jewish holidays are based on it. Therefore,
Rosh Hashanah lands on the first day of the Hebrew month
of Tishrei every year, but it varies on the secular
calendar. Each Hebrew month has 29 or 30 days, and a
year has 12 lunar months plus approximately 11 days.
The months start on the day of the new moon. In order
to bring the calendar in line with the annual solar
cycle, a 13th month of 30 days is added in the 3rd,
6th, 8th, 11th, 14th, 17th, and 19th years of a 19-year
cycle. Therefore, a leap year may have from 383 to 385
The secular, or "Gregorian," calendar has
years of 365 or 366 days. It is divided into 12 months
that have no relationship to the motion of the moon.
In parallel with this system, the concept of weeks groups
the days in sets of 7. There is a leap year every four
The secular calendar is based on Jesus' birth, which
was approximately at the year zero. Every year before
zero is termed Before Christ (BC). Every year after
zero is termed AD for Anno Domini (the year of our lord).
Jews use the terms Before Common Era (BCE) and Common
Era (CE) instead, corresponding to the same years.
Tishrei, Heshvan, Kislev, Tevet, Shevat, Adar I, Adar
II (added in leap years), Nisan, Iyar, Sivan, Tammuz,