THE JEWISH CALENDAR

 The Jewish calendar - also known as the Hebrew calendar - and its history is described on this web page. The Jewish calendar - including the Hebrew months and the Jewish calendrical system of calculating dates - traces its origins to the Babylonian calendar. Regarding Jewish calendar month names, with some rare exceptions, the Hebrew Bible does not mention any months by name; instead it mentions the month by number which is the reason for the "Month Number" column. The months of Cheshvan and Kislev are determined by calculations that depend on which day of the week that the first day of the month of Tishri (or Tishrei) would occur in the following year and on what time of day when the full moon would occur in the month of Tishri in the following year.

Note: Regarding all dates on this Jewish calendar / Hebrew calendar web page, see the footnote near the bottom of this web page.

Why is the Jewish Calendar a Lunisolar Calendar? (Lunisolar = follows the cycle of the moon I.E. lunar, and sun I.E. solar)

The Hebrews needed an understanding of astronomy in order to fix the dates of the festivals. The biblical commandment in the Hebrew Bible to "Keep the month of Aviv" or "Keep the month of Abib" (Devarim or Deuteronomy 16:1) made it necessary to know the position of the sun. In addition, the biblical commandment to "Also observe the moon and sanctify it" (Shemot or Exodus 12:1-2), also made it necessary to know the phases of the moon, hence the need for a lunisolar calendar.

Who originally obtained the exclusive authority to fix the date for Jewish festivals prior to the establishment of the Jewish calendar?

Before the establishment of a Jewish calendar, the identification and designation of Rosh Hodesh ("new moon" in Hebrew) for a given month was critical in fixing the dates for Jewish festivals for that month. The Jewish high court in Judea, known as the Sanhedrin, based in Jerusalem during Temple times, retained its centralized and exclusive authority for fixing the date of Rosh Hodesh as well as for adding an extra month when it deemed necessary, based on the condition of crops at the end of the 12th month. The Sanhedrin based its authority on the fact that if it didn't have the exclusive authority to fix new moon dates, then different Jewish communities would potentially celebrate festivals on different days.

When Does A Jewish Day Begin And End In The Jewish Calendar?

The Jewish day in the Jewish calendar begins at sundown and ends at nightfall on the following day. By extension, the Jewish Sabbath begins at sunset on Friday and ends with the appearance of three stars of the second magnitude on Saturday evening, which is estimated to occur when the sun is seven degrees below the horizon. This rule of seeing three stars also applies to all holy days, and the Talmud bases its support of this rule on the biblical Creation story where at the end of each day, the Hebrew Bible states: "And it was evening and it was morning", in that order (Examples are: Bereshit or Genesis 1:5, 1:8, and 1:13). An exception to this rule is found in rabbinic law, where it states that one can usher in the holy day before the onset of sundown since one can always "add from the secular to the holy" (the secular in this case being a non-holy day).

When Does The Jewish Year Begin?

In Judaism, that depends on the "new year" you are talking about! Say what? Yes, there are four - count'em four "new years"! What're you talking about, you might be saying? (Let's assume you are). Well, in Judaism, the "new year" begins on different dates for different purposes in the Hebrew/Jewish calendar. What is the source for what you are saying, you might be asking? (again, I'm assuming you might be asking that) The source stating that there are four "new years" is Tractate Rosh Hashanah in the Mishnah of the Talmud (Mishnah Rosh Ha-Shanah 1:1 or in other words, Chapter 1, Mishnah 1) which states that there are four new years: (1) 1st day of Nissan or Nisan = The New Year For Kings, Festivals, and Months, this is the date when a king's reign begins, this is also the date for the beginning of the year for the religious calendar described in the Mishnah of the Talmud as the "regalim", meaning the three "pilgrimage festivals" in Hebrew (Pesach/Passover, Shavuot/Shavuoth/Shavuos, and Sukkot/Sukkoth/Succos), since the year's cycle of festivals begins with the pilgrimage to Jerusalem for Pesach/Passover. The festivals were said to have started with the first festival after the first of Nisan, which is Pesach/Passover on the 15th day of Nissan or Nisan. If someone promised to bring a sacrifice or an object to the Temple in Jerusalem within the year, the year was calculated from Pesach/Passover to Pesach/Passover. Only after the three festivals had passed in the order Pesach/Passover, Shavuot/Shavuoth/Shavuos, and Sukkot/Sukkoth/Succos, could the individual be held culpable of withholding the sacrifice or the donation and be punished. This was the case even if the promise was made any time after Pesach/Passover. The punishment was only effected after the three festivals had passed, starting with Pesach/Passover. The 1st day of Nissan or Nisan is also the date for the first month of the Hebrew/Jewish calendar, in other words, months in the Hebrew/Jewish calendar are numbered beginning with the month of Nissan or Nisan as explicitly stated in the Torah of the Hebrew Bible or Tanakh, in the Book of Shemot, otherwise known as the Book of Exodus (Shemot 12:1-2 or Exodus 12:1-2) where it says about the month of Nissan or Nisan: "Hashem (G-d) said to Moshe and Aharon in the Land of Egypt, 'This month shall be for you the beginning of the months; it shall be for you the first of the months of the year.'" (Shemot 12:1-2 or Exodus 12:1-2). In fact, the title "First of the Months" ("Rosh Hodashim" in Hebrew) is reserved in the Torah for the month of Nissan (Shemot 12:2 or Exodus 12:2). Why is Nissan or Nisan the first month in the Hebrew/Jewish calendar? It is because of the momentous transformation, from slavery to physical liberation, of B'nei Yisrael I.E. the Hebrews, after the Exodus from Egypt, that Nissan or Nisan is also referred to as the first month as told in Shemot 12:2 or Exodus 12:2 . In fact, according to the "Ramban", the acronym for Rabbi Moshe ben Nachman Gerondi, also known as "Nahmanides" (1194 - circa 1270, born in Girona, Catalonia, died in Israel, who was a Catalan rabbi, philosopher, Kabbalist and biblical commentator), in his commentary to the Torah or Five Books of Moses, he explains the meaning of the verses of Shemot 12:1-2 or Exodus 12:1-2 as follows:

"The verses mean that this month should be counted first. And beginning with it, should the count proceed to the second, the third, and so on, till the end of the sequence of months with the twelfth month. For the purpose that this month should be a commemoration of the Great Miracle (I.E. Exodus from Egypt). For every time we mention the months, the Miracle will be alluded to. It is for that reason that the months do not have names in the Torah, but rather they are identified by number..."

"And it is similar to the way that days are referenced with reference to the Day of Shabbat (Sabbath); for example, the First Day of Shabbat (for Sunday), and the Second Day of Shabbat (for Monday), as I will explain in the future...Thus, when we call the Month of Nisan (or Nissan) "the first" and Tishrei (or Tishri) "the seventh," the meaning is the first with reference to the Redemption (I.E. Exodus from Egypt) and the seventh with reference to it...".

Based on the above explanation from the Ramban, all months in the Hebrew/Jewish calendar are stated with reference to the Exodus from Egypt that occurred in the month of month of Nissan or Nisan, for instance, the month of Iyar or Iyyar is the "second" month with reference to the Exodus from Egypt that occurred in Nissan or Nisan, the month of Sivan is the "third" month with reference to the Exodus from Egypt, and so on; (2) 1st day of Elul = New Year For Tithing Animals or New Year For The Herds, a day for bringing tithes from one's flock and herd for the Levites ("Levi'im" or "Leviim" in Hebrew) and the Priesthood ("Kohanim" in Hebrew), whose dedication to holy service prevented them from working on the land like the other Hebrew tribes; (3) 1st day of Tishri or Tishrei = New Year For Years (I.E. this is the date for when Creation occurred in Jewish tradition, that is, the creation of the world and of Adam and hence is the date for when the year number changes in the Hebrew/Jewish calendar), that is, just as the 1st day of Nissan or Nisan is the date from when months are counted in the Hebrew/Jewish calendar, the 1st day of Tishri or Tishrei is the date from when the years are counted in the Hebrew/Jewish calendar [the creation of the universe, the sun, and the moon occurred 6 days earlier on the 25th day of Elul 1 BC, with "BC" in this context meaning "Before Creation"], this is also the date for calculating the release year (I.E. the "Shemittah" or "Shemitta" year, which means "Sabbatical" year, which is every 7th year in the 49-year cycle that governed the Kingdom of Israel (10th century B.C.E. to 8th century B.C.E.) and Kingdom of Judah (10th century B.C.E. to 6th century B.C.E.) in biblical times I.E. the 7th, 14th, 21st, 28th, 35th, 42nd, and 49th years), and the date for calculating the Jubilee year (a Jubilee year or "Yovel" year in Hebrew is the year after the 49-year cycle that governed the Kingdom of Israel and Kingdom of Judah in biblical times I.E. the 50th year), this is also the date for plantation, the 1st day of Tishrei or Tishri was also the date that determined the beginning of the year when it came to the three years that a tree must be left ungleaned (Vayikra 19:23 or Leviticus 19:23), and the 1st day of Tishrei or Tishri was also the date for (the tithe of) crops I.E. vegetables for the Levites ("Levi'im" or "Leviim" in Hebrew) and the Priesthood ("Kohanim" in Hebrew), whose dedication to holy service prevented them from working on the land like the other Hebrew tribes; and (4) 1st day of Shevat (according to Rabbi Shammai) or the 15th day of Shevat (according to Rabbi Hillel by whose ruling Jewish people abide) = The New Year For Trees, when tithes from the fruit of trees must be brought for the Levites ("Levi'im" or "Leviim" in Hebrew) and the Priesthood ("Kohanim" in Hebrew), whose dedication to holy service prevented them from working on the land like the other Hebrew tribes.

Since there were originally four new years, at what point did the Jewish people begin to celebrate only two of those new years, which has since been the case up to this day? Since the time of the exile of most of the Jews who lived in the Kingdom of Judah by the conquering Babylonians in either 587 B.C.E. or 586 B.C.E. (secular scholarly dates; Jewish religious scholars state that the exile occurred in either 423 B.C.E., 422 B.C.E., 421 B.C.E., or 420 B.C.E.), both the New Year For Kings and Festivals on the 1st day of Nissan or Nisan and the New Year For Tithing Animals or New Year For The Herds on the 1st day of Elul were discontinued, leaving only the New Year For Years, for plantation and for (the tithe of) crops I.E. vegetables, for calculating Sabbatical and Jubilee years on the 1st day of Tishrei or Tishri, and the New Year For Trees on the 15th day of Shevat as the remaining two new years that are still commemorated by the Jewish people.

The Hebrew/Jewish calendar has a relationship both to natural phenomenon and an inherent connection to the agricultural seasons of Eretz Yisrael ("Land of Israel" in Hebrew) as evidenced by the Torah's reference to the timing of the Pesach/Passover festival in Deuteronomy 16:1 which states that the Hebrews should "Observe the month of the Spring". From this, it is also possible to interpret the reference to the "Tree" in its seasonal context. Tu Bi-Shevat, which is the "The New Year for Trees" in Hebrew, appears in the Second Temple period as the date for calculating the agricultural year in Jewish time. In the Torah, Numbers Chapter 18, the People of Israel are commanded to deduct a tithe of their agricultural produce for the Levites and the Priesthood whose dedication to holy service prevented them from working on the land like the other Hebrew tribes. This is how the rabbinical authors of the Mishnah of the Talmud decided what would be done with agricultural produce and to which year it belonged that is to say, to the outgoing year or to the new year. The Mishnah refers to the "animal tithing", "planting" and "vegetables" to be tithed by the landowner.

When does the month of Nissan or Nisan occur in the Gregorian calendar? According to the original, purely lunar calendar of the Hebrews, when only the cycle of the moon was followed I.E. the lunar cycle or moon cycle (as opposed to the solar cycle which follows the cycle of the sun), twelve lunar months would add up to about 354 days while the solar year is about 365 days. Therefore, the month of Nissan or Nisan in the 354-day Hebrew/Jewish lunar calendar would have "drifted" backwards in the purely solar 365-day Gregorian calendar (or previous to the Gregorian calendar which came out in 1582, the Julian calendar). To minimize this "drift" and keep it balanced with the Gregorian calendar, according to a popular tradition, Hillel II in 358 C.E. or 359 C.E. developed a 19-year cycle lunisolar calendrical system (the word "lunisolar" combines the words "lunar" and "solar" since this new calendrical system used both the cycle of the moon and the cycle of the sun in its calculations) which added an extra month - called Adar II - every 3rd, 6th, 8th, 11th, 14th, 17th, and 19th year of the cycle, beginning at the epoch of the modern Jewish calendar. Hillel's calendar would prevent the month of Nissan or Nisan from constantly "drifting" back, first in the Julian calendar and later on after 1582 in the Gregorian calendar, and keep the month of Nissan or Nissan balanced, first in the Julian calendar, and after 1582, in the Gregorian calendar, by having the month of Nissan or Nisan occurring in either in March or April, first in the Julian calendar, and after 1582, in the Gregorian calendar. The current 19-year cycle began at the start of the Jewish year of 5758 (1 Tishri 5758), which corresponds to the Gregorian date of October 2, 1997.

Originally, the Civil New Year occurred on the 1st of Nissan or Nisan, when the reign of kings was dated beginning on the 1st day of Nissan or Nisan. Later on, after the exile of most of the Jews who lived in the Kingdom of Judah to Babylonia by the conquering Babylonians in either 587 B.C.E. or 586 B.C.E. (these are the secular scholarly dates; religious scholarly dates state that this event occurred in either 423 B.C.E., 422 B.C.E., 421 B.C.E. or 420 B.C.E.), the practise of observing the New Year For Kings and Festivals on the 1st day of Nissan or Nisan was ended and the Civil New Year was changed from the 1st day of Nissan or Nisan to the 1st day of Tishrei (or Tishri), that is, on Rosh Hashanah. The Civil New Year is known as the "head of the year" or "Rosh Ha-Shanah" in Hebrew when the Jewish year number increases and this occurs in the seventh month of the Jewish calendar, the Hebrew month of Tishri (or Tishrei), which occurs in either in September or October in the Gregorian calendar. Note that although Hillel II is reputed by tradition to have developed the modern Hebrew calendar, no mention of this exists in the Talmud, which itself was completed around 500 C.E. Hai Gaon (969-1038), the head of the Pumbeditia, Babylonia Jewish academy of learning in the 11th century was the first person to mention that Hillel had formed the modern Hebrew calendar. In addition, it is impossible to apply modern Jewish calendrical rules to post-Talmudic dates (beyond 500 C.E.). Instead, based on the evidence, it is now widely believed that the arithmetic rules for calculating dates in the modern Jewish calendar were developed in the 7th to 8th centuries in Babylonia by the heads of the Jewish academies of learning, known as the Geonim. Based on the account of the Muslim astronomer al-Khwarizmi, it is also believed that most of the modern arithmetic rules were in place by about 820 C.E. However, the epoch (the start of Year 1 of the Common Era), was placed one year ahead compared with the epoch year in the modern Hebrew calendar. In 921 C.E. or 922 C.E., a person named Aaron ben Meir tried to bring the authority for the Jewish calendar to Israel from Babylonia by asserting an arithmetic argument in favor of Israel being the center for the Jewish calendar which would have resulted in the authority of the Jewish calendar being moved to Israel. However, the Babylonian Jewish academic leader Sa'adiah Gaon opposed him based on his version of the calendrical rules for the modern Jewish calendar and finally, all Jewish communities ignored his opinion. This controversy proved that the rules for the modern Jewish calendar were in place by 921 C.E. or 922 C.E., except for the rules for calculating the year. Finally, in 1178 C.E., Maimonides described in full all of the rules for the modern Jewish calendar, including the rules for determining the modern epochal year.

What is the epochal year in the modern Jewish calendar? The epoch of the modern Hebrew calendar is 1 Tishri AM 1 (AM = anno mundi = in the year of the world), which in the proleptic Julian calendar is Monday, October 7, 3761 B.C.E., the equivalent tabular date (same daylight period). This date is about one year before the traditional Jewish date of Creation on 25 Elul AM 1. A minority place Creation on 25 Adar AM 1, six months earlier, or six months after the modern epoch. Thus, adding 3760 to any Julian/Gregorian year number after 1178 will yield the Hebrew year number beginning in autumn (add 3759 for that ending in autumn). Due to the slow drift of the Jewish calendar relative to the Gregorian calendar, this will be true for about another 20,000 years.

Why are there 29 or 30 days in a month? Since the Jewish calendar is primarily a lunar calendar, the arrival of the new month ("Rosh Hodesh" in Hebrew) is determined by the appearance of the new moon. This is the time when the moon's position in the sky passes that of the Sun. Soon after the moon passes the Sun, one begins to see a sliver or thin crescent of the moon in the sky just after sunset. Although it takes a little over 27 days for the moon to circle the Earth, the Sun also changes its position as well - it takes one year for the Sun to circle the sky. This creates a situation where the moon is "chasing" the Sun from the Earth's viewpoint, and it takes the moon an extra 2 days to catch up with the Sun. Adding the 2 days onto the 27 days means that it takes 29 days, 12 hours, 44 minutes and a fraction to go from one new moon to the next new moon. This means that each Jewish month alternates between 29 and 30 days, for instance, the month of Adar I can be 30 days, followed by Adar II which will be 29 days, followed by Nissan being 30 days, then Iyar being 29 days, then Sivan being 30 days and so on, except that the months of Cheshvan and Kislev have to be adjusted through complex calculations because of the extra 44-plus minutes and for other additional adjustments. There are Hebrew calendar software programs that perform these calculations in order to determine when a new month will begin.

Here's the Jewish calendar or Hebrew calendar:

Name of Month	Month Number	Length of Month	Gregorian Equivalent
Nissan	1	30 days	March-April
Iyar	2	29 days	April-May
Sivan	3	30 days	May-June
Tammuz	4	29 days	June-July
Av	5	30 days	July-August
Elul	6	29 days	August-September
Tishrei	7	30 days	September-October
Cheshvan	8	29 or 30 days	October-November
Kislev	9	29 or 30 days	November-December
Tevet	10	29 days	December-January
Shevat	11	30 days	January-February
Adar	12	29 or 30 days (30 in leap year)	February-March
Adar II	13	29 days	March-April

Notice that the days are fixed from the first month of Nissan to the seventh month of Tishri? Here is an interesting fact: from the first major Jewish holiday to the final major Jewish holiday in the Hebrew calendar the number of days are the same, meaning that the time from Passover in the month of Nissan - the first major Jewish holiday - to the final major Jewish holiday - the festival of Sukkot in the month of Tishri - is always the same, regardless of calendar calculations based on the moon.

According to the Tanakh or Hebrew Bible, there was a civil Hebrew calendar from Genesis 1:1 (Creation) until Exodus 12:1. In Exodus 12:2, G-d said to Moses that because of the Passover event, the month that Passover occurred shall be the "head month", or first month of the Hebrew calendar, so since Passover occurred in the Springtime, the month name that was later assigned by Ezra and identified with the Passover event was the month of Nissan.

Here is a table comparing the Hebrew/Jewish civil calendar and civil month number with the Hebrew/Jewish religious calendar and religious month number, respectively:

Civil Calendar	Month Number	Religious Calendar	Month Number
Tishri	1	Nisan or Nissan (Aviv = "Spring" in Hebrew)	1
Heshvan or Cheshvan	2	Iyar	2
Kislev	3	Sivan	3
Tevet	4	Tammuz	4
Shevat	5	Av	5
Adar	6	Elul	6
Nisan or Nissan (Aviv)	7	Tishrei	7
Iyar	8	Heshvan or Cheshvan	8
Sivan	9	Kislev	9
Tammuz	10	Tevet	10
Av	11	Shevat	11
Elul	12	Adar	12

Who chose the names of the Hebrew months? Following his return from exile in Babylonia, Ezra chose the names of the Hebrew months. As mentioned, with rare exceptions, the Hebrew Bible does not refer to months by name, it only refers to months by number such as "the first month", "the eighth month", and so on. Ezra chose the Hebrew month names from the names of the months in the Babylonian calendar in Babylonia where Ezra and many other Jews had been exiled following the Babylonian conquest of the Kingdom of Judah in 587 B.C.E. or 586 B.C.E. After the Persians conquered the Chaldeans who ruled Babylonia in 539 B.C.E. (alternate date claims: 538 B.C.E., 537 B.C.E., and 536 B.C.E.), King Cyrus the Great of Persia allowed Ezra, Nehemiah and the other exiled Hebrews to return to Jerusalem where Ezra established the names of the Hebrew months. While in Babylonia, the exiled Jews spoke Aramaic, the language of Babylonia and a sister language of Hebrew, and so they chose the Babylonian month names based on their understanding and familiarity with that calendar.

Here are the names of the months in the Babylonian calendar, starting from the first to the final month, followed by the Hebrew month equivalent, and the order of the Hebrew months. Notice that the Babylonian month of Shabatu comes before Tebetu, whereas in the Hebrew/Jewish calendar, Tevet comes first, then Shevat:

Babylonian Month Name	Month Number	Hebrew Month Name	Month Number
Nisanu	1	Nissan	1
Ayaru	2	Iyar	2
Simanu	3	Sivan	3
Du'uzu	4	Tammuz	4
Abu	5	Av	5
Ululu	6	Elul	6
Tashritu	7	Tishrei	7
Arach-Samna	8	Cheshvan	8
Kislimu	9	Kislev	9
Shabatu	10	Shevat	11
Tebetu	11	Tevet	10
Adaru	12	Adar	12

The names of the Babylonian months come from the Akkadian language, a Semitic language which originated in the city of Akkad, in northern Babylonia. Akkadian was spoken in Babylonia before the 10th century B.C.E. By the late 10th century - early 9th century B.C.E., Aramaic replaced both Akkadian and Hebrew as the spoken language in Babylonia. By about 600 B.C.E., Babylonian astronomers had identified the ecliptic, meaning the sun's apparent course around the earth, and they divided this course into 12 parts (meaning they divided this course up into 12 months), each named for a constellation in which the sun rose during that period. The sun determined the length of the year by its passage through the 12 parts, with the moon passing through all of them in 29 1/2 days. Our horoscope is a direct descendant of the Babylonian system of calculation since the day, which was a 24-hour period, was broken up into 12 segments, the 12 segments into periods of 30-degree segments each, and those, in turn, broken down into 60 minutes and finally further divided into 60 seconds. The Babylonian astronomers based their division of the ecliptic course of the sun around the earth into 12 parts and the day into two sets of 12 hours, one set of 12 hours for the day, and the other set of 12 hours for the night on their base 60 I.E. "sexagesimal" counting system in which the number 12 is divisible into the number 60. The Babylonian year began at the first New Moon (actually the first visible crescent) after the Vernal Equinox. Later on, the Greeks adopted this method of dividing up the heavens and time, calling this set of 12 calendrical constellations, the zodiac ("zodion" means "animal figure" in Greek). The beginning of the Babylonian month in the Babylonian calendar was determined by the direct observation by priests of the young crescent moon low on the western horizon at sunset after the astronomical New Moon. This custom is remembered in Judaism and Islam with the principle that the new calendar day begins at sunset.

The practice of sighting the first visible crescent of the first New Moon after the Vernal Equinox resulted in the Babylonian calendar running out of step with the solar calendar. In order to keep the Babylonian calendar aligned with the solar calendar, extra months had to be added, so the king of Babylonia originally chose which month had to be added and when it had to added, but this only served to add greater confusion to the calendar. After Babylon was captured by the Persian king Cyrus the Great in 539 B.C.E. (alternate date claims: 538 B.C.E., 537 B.C.E., and 536 B.C.E.), priestly officials took over from the Babylonian astronomers. The priestly officials now started to look for a standard procedure for the addition or intercalation of months. It was introduced in 503 B.C.E. by Darius I the Great (if not earlier) and contained 7 leap years in a 19-year calendrical cycle. An extra month called "Addaru II" was added in the 3rd, 6th, 8th, 11th, 14th, and 19th years of a 19-year calendrical cycle. This accounted for 6 leap years. The 7th leap year contained an extra month in the 17th year of the 19-year cycle called "Ululu II", and its length was 29 days. By doing this, the cycle came out even with the solar calendar year, and the first day of the month of Nisanu - New Year's Day in the calendar - was never far off from the Vernal Equinox (the first day of Spring), resulting in the civil calendar and the seasons never being out of step.

After it was discovered (or perhaps borrowed from the Babylonians and Persians and developed) by the Greek mathematician, astronomer, and engineer Meton of Athens in 432 B.C.E. who worked closely with another Greek astronomer, Euctemon, that 235 lunar months are almost identical to 19 solar years (the difference is only 2 hours), a lunisolar calendrical system of adding months to a lunar calendar to align it with the solar calendar based on this discovery was created and called the "Metonic Cycle". From the Metonic Cycle, priestly officials in Persia gradually developed astronomical rules over time so that a 19-year calendrical cycle was established in the 4th century B.C.E. in Persia for the purposes of aligning the months of the Babylonian lunar calendar (about 354 days) with the solar calendar year (about 365 days). The Persian priestly officials concluded that seven out of nineteen years should be leap years containing an extra month. The king still announced that an extra month had to be added, but now he based his announcement on the advice of a priestly official/astronomer.

The Babylonians actually had two calendars: a lunar calendar which was used for religious purposes and a solar calendar which was used for astronomical purposes. Both calendars utilized a 12-month system, and the Babylonian day began at sunset. As mentioned, the Jewish calendar and Islamic calendar also followed suit, beginning their day at sunset and also adhering to the Metonic Cycle established by Meton of Athens.

The week is a cycle that is purely artificial: it is not based on natural planetary movements or changes in the environment, as is the yearly cycle. The week is purely based on mathematical logic: the cycle of the week repeats itself indefinitely. The week is not attuned to the other divisions of time; rather, it intersects with other divisions of time. An example of this is that the 365-day year has 12 full months but not a full number of weeks; instead, the 365-day year has 52 weeks plus another day or two. Many reasons exist as to the origin of this rhythm of 52 groups (usually of 7) among different peoples; in the case of Judaism, Christianity, and Islam, there were religious motives. Other cultures based the system of 52 weeks on economic reasons, divinatory cycles, and even the operation of a market economy. The 7-day week originated in Mesopotamia, perhaps going as far back as the 15th century B.C.E. The Babylonian astronomers named the seven days of the week for the sun, moon, and five planets that were known to them.

Besides the different order of the months in the Babylonian and Hebrew calendars, one can see from the previous chart that the Babylonians seemed fond of the letter "u" in their month names. Other differences include the three Babylonian months containing the letter "m" were replaced by the Hebrews with the letter "v" (or "w"), the Babylonian month name of Du'uzu was replaced with the month name of Tammuz, and the Babylonian month of Arach-samna was replaced with the month name of Marcheshvan, and this month name was eventually shortened to Cheshvan.

The Jewish people were the first people to organize their life around the weekly cycle. They justified the seven day week on the basis of the verse from the Book of Genesis, where it is stated that G-d created the world in six days and on the seventh day He rested. While in captivity in Babylonia, the Jews began a strict observance of Shabbat, or the Sabbath, which is the period of rest on the seventh day. Since the exiled Jews in Babylonia were unable to pray in their Temple in Jerusalem, it having been destroyed by the Babylonians when they conquered the Kingdom of Judah in 587 B.C.E. or 586 B.C.E., and deporting most of the Jews to Babylonia, the Jews created in time what they lost in space: giving the seventh day of the week (Saturday) to G-d in the form of Shabbat, or the Sabbath. In fact, Shabbat is so holy to the Jewish people that in the Jewish calendar, the days are designated by their position in relation to Shabbat I.E. the sixth day before Shabbat, the fifth day before Shabbat, and so on. Exodus 20:8-11 reflects how the week is deeply embedded in Biblical tradition. The "day of rest", the seventh day, is in fact part of the 10 Commandments: "Remember the Sabbath day, to keep it holy. Six days shalt thou labor, and do all thy work; but the seventh day is the Sabbath of the L-rd thy G-d; in it thou shalt not do any work...For in six days the L-rd made heaven and earth, the sea, and all that in them is, and rested on the seventh day: wherefore the L-rd blessed the Sabbath day, and hallowed it" (Exodus 20:8-11).

Here is a chart outlining the Hebrew name for the days of the week, its Gregorian calendar equivalent, and the meaning of each Hebrew name for the days of the week. As mentioned, the Hebrew names for the first six days of the week remind us that the spiritual goal of the week is the day of unity and wholeness - Shabbat or the Sabbath. Each day of the week reminds us that we are preparing for the "peace" - the "shalom" in Hebrew - meaning unity and wholeness - of Shabbat or the Sabbath:

Hebrew Name For The Days Of The Week	Gregorian Name For The Days Of The Week	Meaning of Hebrew Day Name
Yom Rishon B'Shabbat	Sunday	the first weekday of the approaching Shabbat
Yom Sheini B'Shabbat	Monday	the second weekday of the approaching Shabbat
Yom Sh'lishi B'Shabbat	Tuesday	the third weekday of the approaching Shabbat
Yom Revi'i B'Shabbat	Wednesday	the fourth weekday of the approaching Shabbat
Yom Chamishi B'Shabbat	Thursday	the fifth weekday of the approaching Shabbat
Yom Shishi B'Shabbat	Friday	the sixth weekday of the approaching Shabbat
Shabbat	Saturday	Sabbath

The Hebrew calendar has had three forms: (1) Biblical times: the first form, dating from the time before the destruction of the Second Temple in Jerusalem in 70 C.E. by the Romans, was a calendar based on observations; (2) Talmudic times: the second form, in effect during the Talmudic period (about 10 B.C.E. to about 500 C.E.), was based on observations and calculations; and (3) Post-Talmudic times: the third form, was based solely on calculations that defined rules for a calendar initially described in full by Moses Maimonides in 1178 C.E. From 70 C.E. to 1178 C.E, there was a gradual transition from the second to the third form, with more and more calendrical rules being adopted over that period. The rules that were developed attained their final form either before 921 C.E. or before 820 C.E. However, because the modern lunisolar Hebrew calendar had to add extra months to synchronize itself with the Christian solar calendar, starting with three consecutive years that were given extra months in the 2nd century C.E. according to the Talmud, the modern Hebrew calendar cannot be used for determining Biblical dates because new moon dates may be in error up to four days and months may be in error up to four months.

The Tanakh ("Hebrew Bible" in Hebrew) for the most part mentions the Hebrew months by number only. Exceptions are as follows: Nissan or Nisan is mentioned in Nehemiah 2:1 and Esther 3:7; Kislev is mentioned in the following verses: Zechariah 7:1 and Nehemiah 1:1; Elul is mentioned in Nehemiah 6:15; Tevet is mentioned in Esther 2:16 although its meaning is obscure; Shevat is mentioned in Zechariah 1:7; Sivan is mentioned in Esther 8:9; and Adar/Adar II is mentioned in Ezra 6:15, as well as eight times in the Book of Esther (Esther 3:7, 3:13, 8:12, 9:1, 9:15, 9:17, 9:19, and 9:21). The word Tammuz is used once in the Hebrew Bible in Ezekiel 8:14. However, it is not used in the context of a month name, but as the name of an idol. Also, Joshua 15:3 mentions and describes the name and geographical location called "Adar" or "Addar" (meaning "high" in this context in Hebrew) that runs along the southern boundary of Judah. Another biblical reference to the name and geographical location of Adar or Addar - also known as "Hazar-addar" - is referenced in Numbers 34:4. In another context referenced in the Hebrew Bible, "Adar" or "Addar" - meaning "mighty one" in Hebrew in this context, is a male, who is the son of Bela (1 Chronicles 8:3), and who is also known as "Ard" (Numbers 26:40).

In Pre-Exilic times (meaning prior to 587 B.C.E. or 586 B.C.E., before the Babylonians conquered the Kingdom of Judah), the names of four months are mentioned: Aviv or Abib (first), Ziv (second), Eisanim or Ethanim (seventh), and Bul (eighth). However, these four names are actually derived from the Canaanites and at least two of these names are Phoenician names. All four references to these month names are mentioned in the account of Solomon's relation with the Phoenicians and their assistance with the construction of the First Temple (1 Kings 6:1, 6:37, 6:38; 8:2). In fact, in 3 of the 4 instances in which they appear, the Biblical text goes out of its way to translate them into Torah month names with the formula: "in the month [Foreign name], which is the [Torah name] month." Thus we read, "in the month Ziv, which is the second month", "in the month Eisanim (or Ethanim), which is the seventh month", "in the month Bul, which is the eighth month". Each of the other foreign-named months that would have had their Hebrew month mentioned in the form of a numerical equivalent according to the aforementioned formula were simply not recorded in the Hebrew Bible (unless you believe in Torah codes and the like, then perhaps they can be discovered via that route!). Furthermore, in the Hebrew Bible, there are descriptive names for each of the four Pre-Exilic months mentioned that reference historical meanings for each of the four respective Pre-Exilic months: Nissan is called the month of Aviv or Abib: "Spring" (Exodus 13:4, 23:15, 34:18; Deuteronomy 16:1); Iyyar is called the month of Ziv: "Radiance" (I Kings 6:1, 6:37); Tishri is called the month of "Eisanim" or "Ethanim": "Natural Forces" (I Kings 8:2), and Cheshivan or Heshivan is called the month of the "Bul": in reference to the bountiful harvests associated with the season (I Kings 6:38). The distinction between the four Pre-Exilic months and the current Post-Exilic Hebrew month names is that the latter were derived from Aramaic scribal practices for denoting Babylonian month names (Aramaic was the language of Babylonia when the exiled Jews were there) while the former were derived from Caananitic and Phoenician month names. When the Jews in the Kingdom of Judah were conquered by the Babylonians in 587 B.C.E. or 586 B.C.E. and mostly transported into Exile to Babylonia, while in Babylonia, they adopted Babylonian names for the months. The Babylonian calendar, in turn, was a direct descendant of the Sumerian calendar. However, not all Jews consistently adopted the Babylonian calendar from that point on. The Jewish sect known as the Essenes - the creators of the Dead Sea scrolls - had adopted a solar calendar for the final two centuries before the Common Era. This solar calendar may have been the 364-day solar calendar mentioned in the non-canonical books of Enoch and Jubilees. Intercalations (adding an extra month) would have had to be used to keep this solar calendar aligned with the 365 1/4-day standard solar calendar. In addition, the Samaritans and the Sadducees each had their own calendars. The Samaritan calendar fixes the first day of the month by the conjunction of the moon with the sun, not by the new moon, and their months are numbered, not named. Although the Samaritan calendar adds an extra month for leap years seven times in a 19-year cycle like the Jewish calendar, unlike the Jewish calendar, months are not added or intercalated at set intervals. Even the Jews of certain communities didn't always follow the calendrical rulings of rabbis. For instance, the Syrian Jews of Antioch from 328 C.E. to 342 C.E. always celebrated Pesach or Passover in March, regardless of rabbinical calendrical rulings in Israel. Within Israel itself, the Karaites followed Muslim practice and returned to observing and determining the date of the new moon. This practice continued among Karaites until the 11th century C.E., when a branch of the Karaites, the Crimean Karaites, decided to adopt mathematical rules for calculating their calendar, similar to what was done for the rabbinical calendar, and these calculations were to be a supplement, rather than a replacement, for the Karaite calendar, which again, was based on observations. The calendar of the Ethiopian-Jews, or Beta Israel, uses a lunisolar system, with a leap year every fourth year.

As mentioned in the previous paragraph, when the Jews were permitted to return to Judea after the Persians conquered the Babylonians in 539 B.C.E. (alternate date claims: 538 B.C.E., 537 B.C.E., and 536 B.C.E.), they retained the Babylonian month names as a reminder of the redemption from Babylon, which resulted in the rebuilding of the Second Temple. The ancient Rabbis mention that the names of the months returned with us to the Land of Israel from Babylon (see: Jerusalem Talmud, Rosh Hashanah Chapter 1, halakhah 2). Prior to being deported to Babylon, for the most part, the Hebrew month names were each known by a number in relation to and in remembrance of the Exodus from Egypt I.E. "the first month from Nissan" (the month of Nissan is when the Exodus occurred), the "second month from Nissan", and so on. But after returning from Babylon, and seeing that the scriptural saying came to pass from the Book of Jeremiah (Jeremiah 16:14-15): "Assuredly, a time is coming - declares the Eternal - when it shall no more be said, 'As the Eternal lives who brought the Israelites out of the land of Egypt,' but rather, 'As the Eternal lives who brought the Israelites out of the northland, ...", the Jews switched to referring to the Hebrew months by their Babylonian names in order to remember that we were there and that Blessed G-d brought us up from there. With the switch to calling the Hebrew months by their Babylonian names rather than by a number in relation to the Exodus from Egypt (recalling the first redemption of the Hebrews), we are remembering the second redemption (or Exodus) of the Hebrews/Jews from Babylonia in this manner.

As mentioned earlier, according to a popular tradition, the current Hebrew calendar was established in 358 C.E. or 359 C.E. by Hillel II who was president of the Jewish court of the Sanhedrin, but many Jewish scholars now believe that the current Hebrew calendar was established by the Geonim of Babylonia in the 7th and 8th centuries C.E. The modern Hebrew calendar or Jewish calendar is a religious calendar (as opposed to the civil Hebrew or Jewish calendar) that is now the official calendar of Israel. The Hebrew calendar is lunisolar, meaning that it tries to use both a solar calendar in years and lunar calendar in months. It tries to use the lunar months to approximate one solar or tropical year. This means that a lunisolar calendar attempts to keep the months closely aligned with lunar cycle - or cycle of the moon around the Earth - and at the same time keep the year closely aligned with the seasonal cycles. In practice, this calendar is more successful when tracking and keeping pace with the seasonal cycle in comparison with the lunar cycle. A tropical or solar year has its own months, but they have little if any connection to the lunar cycle. The seasons and years in a purely tropical or solar calendar are usually tied to astronomical systems and begin at or near a fixed point in a season such as the vernal equinox. An example of a purely solar calendar is the Gregorian calendar that is currently in use in the U.S. and many other countries. In a lunisolar calendar, the tropical year is divided up into 12 lunar months. However, the total number of days in 12 lunar months are about 11 days shorter than one tropical year, so a leap or intercalary month is added about every 3rd year to keep the calendar aligned with the seasons, so that the seasons do not 'drift' backwards in the calendar. An additional reason for aligning the lunar year with the solar year is that the biblical festivals are connected to the agricultural seasons of the 365-day solar year, so the difference of 11 days between the lunar calendar and the solar calendar has to be made up. In Temple times, the additional month was added periodically, after an examination of the condition of the crops I.E. the agricultural produce, at the end of the 12th month. Later on, when the 19-year cycle of the Jewish calendar was established, the extra month was added automatically, seven times in the 19-year cycle.

As just mentioned, the Hebrew calendar goes by a 19-year cycle that includes leap years in the 3rd, 6th, 8th, 11th, 14th, 17th and 19th years of the cycle, meaning in those years, an extra month is added to the Jewish calendar to keep it aligned with the solar calendar. The current 19-year cycle began on October 2, 1997 in the Gregorian calendar which is the Hebrew year of 5758. So what do the Hebrew calendar years look like through the 19-year cycle? There are three types of years: (1) a Deficient Year ("Haser" means "deficient" in Hebrew). This is a year in which the months of Cheshvan and Kislev both have 29 days; (2) a Regular Year ("Kesidrah" means "regular" in Hebrew). This is a year in which the month of Cheshvan has 29 days and the month of Kislev has 30 days; and (3) a Complete Year ("Shelemah" means "complete" in Hebrew). This is a year in which the months of Cheshvan and Kislev both contain 30 days.

Another opinion concerning the formation of the Jewish calendar / Hebrew calendar came from the great biblical and Talmudic commentator, Rashi [1040-1105, born in Troyes, in northern France. Rashi is the acronym for Rabbi Solomon ben Isaac (or: Shlomo Yitzhaki or Shlomo Yitzchaki)]. He stated that the 7 days of creation were each 24 hours long, regardless of the date of the creation of the sun. Many Jewish scholars agree with this assertion. However, the opinions of other noted scholars such as the "Rambam" [Rabbi Moses Maimonides, 1135-1204, born in C rdova (or C rdoba), Spain] and the "Ramban" (Rabbi Moshe Ben Nachman, 1194-1270, born in Gerona, Spain) differed with Rashi's assertion.

The following table shows the three types of Hebrew years that occur in the 19-year cycle. The civil Hebrew calendar is used, but this can also apply to the religious Hebrew calendar as well. Non-leap years have either 353, 354, or 355 days, while leap years have either 383, 384, or 385 days:

Month Number and Name	Deficient Year This is a year in which the months of Cheshvan and Kislev both contain 29 days.	Regular Year This is a year in which Cheshvan has 29 days and Kislev has 30 days.	Complete Year This is a year in which the months of Cheshvan and Kislev both contain 30 days.
1. Tishrei	30	30	30
2. Cheshvan	29	29	30
3. Kislev	29	30	30
4. Tevet	29	29	29
5. Shevat	30	30	30
Adar II This month only occurs in a Leap year	30	30	30
6. Adar I	29	29	29
7. Nissan	30	30	30
8. Iyar	29	29	29
9. Sivan	30	30	30
10. Tammuz	29	29	29
11. Av	30	30	30
12. Elul	29	29	29
Total:	353 days or 383 days	354 days or 384 days	355 days or 385 days

Regarding the naming of the two months of Adar, note that some Hebrew calendars may say Adar and Adar I, while others may say Adar I and Adar II, while still others may say Adar and Adar II. These are all different ways of saying the same thing: that there are two months used for the month of Adar when a leap year occurs. In non-leap years, the month of Adar is most often simply called Adar. A final point is that members of the committee in the Jewish court of the Sanhedrin where the lengths of the Jewish months were fixed as well as the intercalation of months were calculated for the Hebrew calendar on a yearly basis did not rely solely on calculations, but also on observations. They added the extra month of Adar if they observed that the harvest was not yet ripe (for instance, if the earing of barley was not yet ready to be harvested), the winter rains had not yet stopped, the fruit on the trees did not grow in the usual way, the lambs were not ready to be slaughtered for Passover, if there was not an adequate number of lambs to be slaughtered for the Passover / Pesach festival at the Temple in Jerusalem, the condition of the roads were not yet dried up for the Passover pilgrims and families to come to Jerusalem to observe the Passover / Pesach festival, and even if young pigeons were not flying after a certain point in time. In addition, the day for the new moon (known as "Rosh Hodesh" in Hebrew, meaning "head of the month" in Hebrew) - and hence new month - was determined when specially appointed eyewitnesses of the Sanhedrin - the Jewish "Supreme Court" and legislative body which was composed of 71 Jewish Sages and based in Jerusalem - would see the first crescent of the new moon and report this sighting to the Sanhedrin which accepted testimonies from two independent, reliable eyewitnesses. The members of the Sanhedrin would also use calculations in conjunction with the accounts of the two eyewitnesses to determine the new moon. A special court of three members of The Sanhedrin (not the entire membership of The Sanhedrin, which was led by a Patriarch) met on the 29th of each month to await the report of the two eyewitnesses. If the two eyewitnesses arrived on the 29th day or 30th day of the month, then the two eyewitnesses were individually cross-examined by the members of the Sanhedrin in order to verify their testimony. If both their accounts were consistent with each other - meaning there were no contradictions in the testimonies from both eyewitnesses - and each testimony was individually correct and were in agreement with the calculations made to determine the expected new moon by the members of the Sanhedrin, then the new moon would be officially confirmed and a new month would be established. If, however, the individual accounts by either or both of the eyewitnesses were either false, inconclusive, or no witnesses had arrived by the 30th day of the current month to report their sighting of the first crescent of the new moon, then the new moon and hence new month was determined solely on the calculations made by the members of the Sanhedrin. Since a Jewish lunar month contained either 29 days or 30 days, if the eyewitnesses arrived on the 30th of the month and testified that they had seen the first crescent of the new moon, then that day became the first day of the new month and the previous month was declared to be 29 days in length. If no eyewitnesses arrived at the Sanhedrin on the 30th day of the month to report the sighting of the first crescent of the new moon, then the previous month was declared to be 30 days in length and the next month would begin on the 31st day. Once the two individual testimonies of the eyewitnesses were accepted by the Sanhedrin court based on their own calculations in comparison with these observations, the members of the Sanhedrin would then send out messengers to declare the date of the new month to the Jewish people as well as the date or dates for any Jewish holiday and/or Jewish festival that was commemorated during the new month. Initially, the date of the new month and date or dates for any Jewish holiday and/or festival for that month were announced by carrying torches that were used to light signal fires on mountaintops that were located near the main Jewish communities that lived beyond Israel's borders. This included the Jewish communities which were located west of Israel in Egypt and the Jewish communities which were located northeast of Israel and which extended all the way to Babylon, then the capital city of Babylonia (now in present-day Iraq) as well as other major Jewish communities in Babylonia. The signal fires were first lit on the Mount of Olives in Jerusalem and, as mentioned, extended both westward to Egypt and northeastward all the way to distant Babylon, but the Samaritans, Sadducees, and Boethusaeans or Boethusians (either an outgrowth or related group to the Sadducees) began to light false fires, and so the Sages of the Sanhedrin instead chose to use special messengers that were sent to first inform the people of Jerusalem of the date for the new month and the date or dates of any Jewish holiday and/or Jewish festival for that month, then the rest of Israel was informed, and then finally the outlying Jewish communities beyond Israel were informed. The Hebrew months which contained a Jewish festival include the Hebrew month of Nissan or Nisan for the festival of Pesach/Passover, the Hebrew month of Sivan for the festival of Shavuot/Shavuoth/Shavuos, and the Hebrew month of Tishri or Tishrei for the festival of Sukkot/Sukkoth/Succos. However, these messengers could not reach all the Jewish communities outside Israel either within one day to report the sighting of the new moon for the upcoming month and hence the date for the start of the new month or in the case of reporting the date of a festival and/or holiday in that month, by the date of the festival or holiday, so in the case of the festivals, to eliminate potential uncertainty among Jewish communities outside of Israel concerning the date for a festival within that month, the Sages of the Sanhedrin instituted a second day for celebrating the festivals for the Jewish communities outside of Israel to ensure that no mistake would be made concerning when to start celebrating a festival. In the case of Rosh Hashanah, the Jewish New Year, since it begins on the first day of the Hebrew month of Tishri or Tishrei (source for observing Rosh Hashanah is in the Tanakh or Hebrew Bible, in Leviticus 23:23-25), and because of the uncertainty over when the new moon and hence 1st day of the new month would be officially announced by the Sages of the Sanhedrin which depended on the arrival of the two witnesses to the Sanhedrin by the 30th day in the month in Jerusalem to report their sighting of the first crescent of the new moon, not to mention it being almost impossible to relay that information to all Jews who lived beyond Jerusalem let alone beyond Israel, an extra day was added to Rosh Hashanah by the Sages of the Sanhedrin to ensure that Rosh Hashanah would be commemorated on the appropriate day, making Rosh Hashanah a two-day holiday both for Jews living inside and outside Israel, the only Jewish holiday that is celebrated for two days by Jews living both inside and outside Israel. Thus, Rosh Hashanah has been a two-day holiday for Orthodox Jews and Conservative Jews since the late Second Temple period (1 C.E. until 70 C.E.) when the Sanhedrin decree making Rosh Hashanah extend for two days was established. In the case of Rosh Hodesh, meaning the first day of the new month, an extra day was added by the Sanhedrin Sages for upcoming months in which the eyewitnesses did not appear at the Sanhedrin in Jerusalem on the 30th day of the previous month to report sighting the new moon.

There is, however, a difference between the holiness of the two-day festival holidays of Pesach/Passover, Shavuot/Shavuoth/Shavuos, and Sukkot/Sukkoth/Succos that are observed outside Israel and the two-day holiday of Rosh Hashanah that is observed both inside and outside Israel. The holiness of the second day of the two-day festival holidays that are celebrated by Jews living outside Israel is not considered a rabbinical addition; rather, the two-day holiday of Rosh Hashanah is officially considered by rabbinical tradition to be one long day or holy-day I.E. holiday. This applies to Jews living both inside and outside Israel.

At the time when this web page was started, the year in the Hebrew calendar was 5763 (2003 in the Gregorian or Christian calendar). The big question is (drum roll please!): what is the origin of the numbering of years in the Hebrew calendar? The answer is that the year number in the Hebrew calendar represents in the number of years since the beginning of the Creation of the World (Genesis 1:1). This number is determined by adding up the ages of people in the Hebrew Bible since Creation. More specifically, the birth of Adam on the 6th day of Creation is the actual starting point for counting the years in the Hebrew calendar. At first glance, given the year 5763, this would mean that the world began in either 3761 B.C.E. (if one applies the Hebrew/Jewish calendar to either the Gregorian calendar, which in its traditional version, has no Year 0, or before 1582, the Julian calendar which preceded the Gregorian calendar, which also has no Year 0) or 3760 B.C.E. (if one applies the Hebrew/Jewish calendar to the modern Gregorian calendar which includes a Year 0), and that either 3761 B.C.E. or 3760 B.C.E. was Year 1 in the Hebrew calendar. However, the meaning of what a "day" is in the Hebrew bible is not what we think a day means in the sense of a 24-hour day. Even the concept of a "day" in the seven days of creation does not represent a 24-hour day according to Orthodox Jews since they point out that the Sun did not appear until the 4th "day". Until the 4th "day", they reason, the idea of a 24-hour "day" would be meaningless. Therefore, the Hebrew year number is not necessarily supposed to represent a scientific fact.

Want a list of the entire Jewish calendar and its religious events and holidays complete with the days of their observance in the Jewish calendar? I compiled all of them just below here for you to check out:

Jewish Holiday Calendar

I also have a table outlining the Jewish calendar months in relation to the harvest schedule in Israel at the following link:

Jewish Calendar Months

As well, I have a comparison chart of the Jewish calendar months - both Pre-Exilic and Post-Exilic - with the origin of the Jewish calendar month names and their meanings at the following link:

Months of the Jewish Calendar - History and Meaning

Special Sabbaths, or Special Shabbatot, dot the Jewish calendar. These Special Sabbaths or Special Shabbatot set the mood for upcoming festivals or holidays in the Jewish calendar. The following link on my website contains a list of the Special Shabbatot or Special Sabbaths in the Jewish calendar.

Finally, if that isn't enough for you, I have developed a chart listing the Jewish calendar month names (Pre-Exilic and Post-Exilic), the Babylonian month names, the zodiac sign or constellation sign corresponding to each month name, and the reference(s) to each Jewish calendar month name, if it exists or they exist, in the Hebrew Bible at the following link:

Jewish Calendar Month Names and the Zodiac

Fast Facts About The Jewish Calendar

• Jewish calendar needed to synchronize solar year (365 1/4 days) with the lunar cycles (29 1/2 day months).
• The Jewish calendar has 12 lunar months (from crescent to crescent) of 29 or 30 days each (1 Kings 4:7).
• One embolismic month is added to the Jewish calendar (called: Adar II) in 7 out of every 19 years to synchronize the solar calendar cycle with the lunar cycles.
• Adar II is added in years 3,6,8,11,14,17, and 19 of the 19-year cycle
• The Jewish religious year begins with the month of Aviv/Nisan, which is in either March or April in the Gregorian calendar (Exodus 12:1-3, Exodus 13:3-4, Exodus 23:15, Exodus 3:7)
• The four Pre-Exilic month names (Aviv, Ziv, Eisanim or Ethanim, and Bul) are of Canaanite (and possibly Phoenician) origin, Post-Exilic month names (Nisan or Nissan, Iyar or Iyyar, etc.) are the Hebrew equivalent of the Babylonian month names.
• The Jewish civil year begins with the 7th religious year month, which is Eisanim or Ethanim/Tishrei or Tishri, and is in either September or October in the Gregorian calendar (Exodus 23:16, Exodus 34:22).
• The civil year reckoning originated prior to the religious year reckoning.
• The civil year also marked the beginning of argricultural, sabbatical, and jubilee years.
• Agricultural year - autumn (early rains), winter (rains), spring (latter rains), summer (long, hot, dry).
• Sabbatical years (every 7th year).
• No sowing or reaping (Leviticus 25:2, 25:7, 25:20, 25:22).
• Cancel debts (Deuteronomy 15:1).
• Fellow Hebrew servants released (Deuteronomy 15:12).
• Jubilee years (after 7 weeks of years, 50th year) (Leviticus 25:8-12).
• Land returns to original owners (Leviticus 25:13-17, 25:23, 25:24).
• Biblical days go from sundown to sundown (Genesis 1:5, 1:8, 1:13, 1:19, 1:23, 1:31; Leviticus 23:27, 23:32; Numbers 19:16, 19:19).
• 1 hour = 1/12 the period from sunrise to sunset.
• Example hours: 1st = 6-7 P.M., 3rd = 8-9 P.M., 6th = 11 P.M. - Midnight, 9th = 2-3 A.M., 12th = 5-6 A.M.
• Note that Roman hours started from midnight, rather than from sundown.
• The night was divided into 3 watches of 4 hours each.
• 7 day weeks with the 7th day (Saturday) being the weekly Shabbat or Sabbath.
• Note that there is no physical cycle of 7 days, it came from G-d in Eden (Genesis 2:2-3; Exodus 20:8-11) and is based on mathematical calculations.
• All dates are based on the Jewish religious calendar (where 1/1 is first day of Aviv/Nisan or Nissan)
• There were 7 special annual ceremonial events I.E. sacred assemblies, feasts (Leviticus 23:1-44)
• The 7 special annual ceremonial events are: Festival of the Passover (I.E. lamb) Offering, Feast of Unleavened Bread, Omer Offering [the day of the Omer (sheaf of barley) Offering was the 1st day of the Counting of the Omer], Shavuot, Rosh Ha-Shanah, Yom Kippur, and Sukkot.
• These events included 7 special days that were considered Sabbaths because of their work restriction.
• These 7 special days are, by the Jewish religious calendar: 1/15, 1/21, 3/6, 7/1, 7/10, 7/15, and 7/22.
• The ceremonial Sabbaths were distinguished from the weekly Sabbaths of the Ten Commandments (Leviticus 23:1-4, 23:37, 23:38).
• Where in the Hebrew Bible is the date of Passover mentioned? Answer: Exodus 12:1-14, 34:25, Leviticus 23:5, Numbers 28:16, and Deuteronomy 16:1-8, 16:12.
• Where in the Hebrew Bible does it mention the length of the Passover festival? Answer: Exodus 23:15, Exodus 34:18, Leviticus 23:6-8, Numbers 28:17-25, and Deuteronomy 16:3, 16:4, 16:8.
• Festival of the Passover (I.E. lamb) Offering: 1/14 (Exodus 12:1-14, Exodus 34:25, Leviticus 23:5, Numbers 28:16, Deuteronomy 16:1-8,12)
• Slaying of the Passover lamb: Lamb slayed in late afternoon (just before sunset) (Exodus 12:6, Deuteronomy 16:5,6)
• Hebrew phrase is literally "between the two evenings" (Biblical days begin at sunset and end at sunset).
• Qualifier "when the sun goes down" (Deuteronomy 16:6) indicates the period of the day just prior to sunset.
• Lamb eaten after sundown of 1/14 (early hours of 1/15) (Exodus 12:6-8).
• Feast of Unleavened Bread: 1/15 - 1/21 (seven days) (Exodus 23:15, Exodus 34:18, Leviticus 23:6-8, Numbers 28:17-25, Deuteronomy 16:3,4,8)
• 1/15 and 1/21 are ceremonial Sabbaths.
• Omer Offering: 1/16, the day after the 1/15 ceremonial Sabbath (Leviticus 23:10-14 compare Leviticus 23:6 and Leviticus 23:14)
• A sheaf of the first fruits of the barley harvest is waved before the L-rd.
• Shavuot (Feast of Harvest, Feast of Weeks): 3/6, 7 weeks (50 days inclusive) starting from the Day of the Omer Offering or the Day of Wave Sheaf (2nd evening of Passover/Pesach) (Exodus 23:15-21, Exodus 34:22, Leviticus 23:15,16, Numbers 28:26-31, Deuteronomy 16:9-11)
• 3/6 is a ceremonial Sabbath.
• Offering of new grain from the wheat harvest.
• Shavuot is known as Pentecost in the New Testament, from the Greek word meaning "fiftieth".
• Rosh Ha-Shanah: 7/1 (Leviticus 23:23-25, Numbers 29:1-6).
• 7/1 is a ceremonial Sabbath.
• Announcing the imminent arrival of Yom Kippur I.E. the Day of Atonement, signaling the people to prepare for judgement.
• Yom Kippur (Day of Atonement): 7/10 (Leviticus 16, Leviticus 23:27-32, Numbers 29:7-11).
• 7/10 is a ceremonial Sabbath.
• Most solemn day of year - Judgement (Leviticus 16:21,22).
• Any person who does not afflict his soul is cut off (Leviticus 16:29, Leviticus 23:27-30).
• Cleansing of the sanctuary and the genuine people of G-d (Leviticus 16:17,30,33).
• Sukkot (Feast of Tabernacles, Feast of Ingathering)
• 7/15 - 7/21 (seven days) (Exodus 23:16, Exodus 34:22, Leviticus 23:33-43, Numbers 29:12-38, Deuteronomy 16:13-15).
• 7/15 and 7/22 (eight day) are ceremonial Sabbaths.
• Gather in (ingathering) vintage and olive crops at the end of the agricultural year (Exodus 23:16, Leviticus 23:39).
• Threshing floor, winepress (Deuteronomy 16:13).
• Simchat Torah: Rejoicing, joy complete (Leviticus 23:40, Deuteronomy 16:14,15).
• Shemini Atzeret: The closing assembly of the annual festival cycle (Leviticus 23:36,37)

If you're interested in generating a calendar of Jewish Holidays online for any year between 0001 and 9999, you can go to an Interactive Jewish Calendar. If you would just like to convert dates from Gregorian to Hebrew or from Hebrew to Gregorian, you can go to a Hebrew Date Converter.

Footnote regarding the dates on this Jewish calendar / Hebrew calendar web page: all dates discussed on this website are based on the modern Gregorian calendar, however, these dates are but one secular scholarly deduction; there are many other secular scholarly deductions as well as traditional Jewish chronological dates in addition to modern Hebrew/Jewish calendar dates regarding the timeline of events in Jewish history. To see a table of some important events in Jewish history discussed on this website and their various dates deduced from traditional Jewish sources, the modern Hebrew/Jewish calendar, and secular historical timelines, check out our Jewish History Timeline web page.