Here's a great tip:
Enter your email address and we'll send you our weekly magazine by email with fresh, exciting and thoughtful content that will enrich your inbox and your life, week after week. And it's free.
Oh, and don't forget to like our facebook page too!
Contact Us

Introduction to the Jewish Calendar

Introduction to the Jewish Calendar


Since Biblical times, various astronomical phenomena have been used to establish uniquely Jewish definitions for the day and its hours, the months and the year.

The length of days and hours vary by the season, controlled by the times of sunset, nightfall, dawn and sunrise. The months and years of the Jewish calendar are established by the cycles of the moon and the sun.

Though the months follow the lunar cycle, the lunar months must always align themselves with the seasons of the year, which are governed by the sun. Thus, the Jewish calendar is "Luni-Solar." The discrepancy between the solar year (365 days) and the lunar year (354 days) was resolved by every so often adding a thirteenth month to the year, to form a "leap year."

In the early times of our history, the High Court (Sanhedrin) in Jerusalem was assigned the tasks of determining the beginning of each month and the balancing of the solar with the lunar years. They relied on direct observation of the New Moon, astronomical data, and other considerations.

In the fourth century after the Temple's destruction, however, when oppression and persecution threatened the continued existence of the Court, a fixed calendar was instituted -- based on the Sanhedrin's closely guarded secrets of calendric calculation. This is the permanent calendar according to which the New Moons and festivals are calculated and celebrated today by Jews all over the world.

Like the original system of observation, it is based on the Luni-Solar principle. It also applies certain rules by which complex astronomical calculations are combined with the religious requirements into an amazingly precise system.

The following pages will provide a brief digest of the factors which control the determination of the Jewish hour, day, month and year.

© Copyright, all rights reserved. If you enjoyed this article, we encourage you to distribute it further, provided that you comply with's copyright policy.
Join the discussion
1000 characters remaining
Email me when new comments are posted.
Sort By:
Discussion (40)
October 12, 2016
When is the next "Sabbath year"?
June 25, 2016
first month in the Jewish calender
First month in the Jewish calender, according to Bible?
Subikash C Mishra
August 11, 2015
How to manage the Hotel business on a shabbath day
How to manage the Hotel business on a shabbath day
April 19, 2015
Yom Kippur Katan is observed on the day prior to the beginning of the new month. The following months do not have a Yom Kippur Katan, for various reasons:
Iyar: the day preceding the month of Iyar is in the month of Nissan, when one is prohibited from fasting and mourning.
Tishrei: one may not fast or say penitential prayers on the day before Rosh Hashanah.
Cheshvan: being that Yom Kippur itself has just passed.
Teves: during the days of Chanukah one may not fast or mourn.
Shaul Wolf
April 16, 2015
Yom Kippur Katan
Which months are preceded by a Yom Kippur Katan?
Montpelier, VT
December 15, 2014
Rosh Hashanah (the first day of the seventh month) is the head of the year, while Nissan (the month in which Passover falls, is the first of the months. See Our Other Head for why this is so. Staff
December 5, 2014
First month doesn't mark the New Year?
Why does the Jewish New Year coincide with September when the first month usually coincides with April?
December 2, 2014
To Susara
The Jewish New Year usually coincides with September. Staff
November 27, 2014
when does the Jewish New Year start in relation to our Gregorian calendar?
Pretoria South Africa
June 10, 2014
Jubilee Year
Thank you for your prompt answer. Is the Jubilee Year still observed? When will it occur next?
Since Biblical times the months and years of the Jewish calendar have been established by the cycles of the moon and the sun. Torah law prescribes that the months follow closely the course of the moon, from its birth each month to the next New Moon.
Related Topics
This page in other languages