Jewish Calendar

Rosh Chodesh, the new month, is marked by the appearance of the first sliver of the new moon in the sky above Jerusalem in Israel.
Rosh Chodesh, the new month, is marked by the appearance of the first sliver of the new moon in the sky above Jerusalem in Israel.

The Jewish calendar differs from the common one. It is based on the revolutions of the moon around the earth, whereas the common calendar is based on the earth’s rotation around the sun. The lunar calendar comprises (in a normal year) twelve months each of 29 or 30 days. In a leap year a thirteenth month is added, known as Adar II. A leap year occurs seven times in each cycle of nineteen years; in the third, sixth, eighth, eleventh, fourteenth, seventeenth and nineteenth years. By adding the extra month, the lunar year (354 days) is made to harmonise with the solar year (365 days).

The Hebrew names of the month were adopted from the Babylonian calendar during the Babylonian exile in 586 B.C.E. The first written Jewish calendar was compiled by Hillel II in 359 C.E.

The ‘first month’ of the Jewish calendar is the month of Nissan, in the Israeli spring. However, the Jewish New Year is in Tishrei, the seventh month, and that is when the year number is increased. This concept of different starting points for a year is not as strange as it might seem at first glance.

a diagram showing the Jewish months in order and their relationship to the months of the secular (Gregorian) calendar
This diagram shows the months of the Jewish year in order and approximately when they fall in relation to the months of the secular calendar

The Australian ‘new year’ starts in January, but the Chinese one starts a month or two later. The new ‘financial year’ starts in July, and so on. Similarly, the Jewish calendar has different starting points for different purposes. The days of the New Moon are considered important days in the Jewish calendar (when this will be is calculated according to when there will be a new moon in Jerusalem in Israel). They are known as Rosh Chodesh. On the Sabbath before the New Moon and on the New Moon day itself, special prayers are recited, and Jews celebrate each new month.

To see a list of dates for upcoming Jewish holidays please see our Calendar of Approaching Jewish Dates & Holydays. For more links to other pages, please see further down this page.


Name Number Length Gregorian Equivalent
Nissan 01 30 days March-April
Iyyar 02 29 days April-May
Sivan 03 30 days May-June
Tammuz 04 29 days June-July
Av 05 30 days July-August
Elul 06 29 days August-September
Tishrei 07 30 days September-October
Cheshvan 08 29 or 30 days October-November
Kislev 09 29 or 30 days November-December
Tevet 10 29 days December-January
Sh’vat 11 30 days January-February
Adar 12 29 or 30 days February-March
Adar II (leap year only) 13 29 days March-April

This section of our website has the following pages:


Jewish holiday calendars & Hebrew date converter

Judaism 101: The Jewish Calendar This Week’s Dates

Orthodox Union: Jewish Holidays Community Calendar (calculates the exact times of Jewish holidays in locations around the world)

Recommended Books

Understanding the Jewish Calendar by Nathan Bushwick is an excellent introduction explaining how the system of the Jewish calendar works.

The Comprehensive Hebrew Calendar is an invaluable reference for those needing to convert English dates to Hebrew or back. It is especially useful for calculating things such as when a child’s Bar or Bat Mitzvah may be held. Covers a 200 year period from 1900 to 2100.