The Hebrew Calendar

The western world uses the Gregorian calendar based on the sun. The Jewish calendar is split into twelve months based on the lunar cycle. To bring it in line with the seasons, however, a thirteenth month, Adar Sheni (Adar II) is regularly added. The dates of Jewish holidays do not change from year to year. It just seems that way to us because feast dates fall on different days on the Gregorian calendar.

The Jewish calendar is based on a lunar year of twelve months, each month of twenty-nine or thirty days. The year lasts approximately 354 days. Since the biblical festivals relate to the agricultural seasons of the 365-day solar year, the shortage of eleven days between the lunar and solar years has to be made up. To overcome this problem, a thirteenth month is added in certain years. In Temple times this was done periodically, twelfth month. In a later period the additional month was introduced automatically seven times in a lunar cycle of nineteen years; in the years 3, 6, 8, 11, 14, 17, and 19 of the cycle (Encyclopedia of Judaism 1989).

God called the months by the ordinal/numerical names: first, second, and so on. The names of the twelve months are of Babylonian origin. Israel adopted all twelve months of the Babylonian calendar as their civil calendar, but not all of the twelve months are listed in the Bible. The seven that occur are: Nisan, the first month; Sivan, the third month; Elul, the sixth month; Kislev, the ninth month; Tevet, the tenth month; Shevat, the eleventh month; and Adar, the twelfth month.

Month Length Gregorian Equivalent

Nisan 30 days March-April

Iyar 29 days April-May

Sivan 30 days May-June

Tammuz 29 days June-July

Av 30 days July-August

Elul 29 days August-September

Tishri 30 days September-October

Heshvan 29 or 30 days October-November

Kislev 30 or 29 days November-December

Tevet 29 days December-January

Shevat 30 days January-February

Adar 29 or 30 days February-March

Adar II 29 days March-April

(In leap years, Adar has 30 days. In non-leap years, Adar has 29 days.)

The Civil and Religious Calendars

There are two calendars in the Bible, the civil calendar (Genesis 1:1 to Exod. 12) and the religious calendar. The first month in the civil calendar is Tishri starting in the fall, about September. The seventh month is Nisan (Aviv) starting in the spring, about the time of our March and April.

God changed the civil calendar to the religious calendar in Exodus 12:1 And the LORD spake unto Moses and Aaron in the land of Egypt, saying, This month shall be unto you the beginning of months: it shall be the first month of the year to you. So, now Nisan is the first month of the religious calendar and Tishri is the seventh month (Exod. 13:4). This book starts with the first feast of the religious calendar, Passover.

Civil Calendar Religious Calendar

1. Tishri 1. Nisan (Aviv)

2. Heshvan 2. Iyar

3. Kislev 3. Sivan

4. Tevet 4. Tammuz

5. Shevat 5. Av

6. Adar 6. Elul

7. Nisan 7. Tishri

8. Iyar 8. Heshvan

9. Sivan 9. Kislev

10. Tammuz 10. Tevet

11. Av 11. Shevat

12. Elul 12. Adar

It is very interesting that the number of days between Nisan and Tishri is always the same. Because of this, the time from the first major festival Passover in Nisan to the last major festival Feast of Tabernacles in Tishri is always the same.

From

A Family Guide to the Biblical Holidays