M. J. Beattie



How Accurate is the Calendar at this Website?



The two calendars published at cgsf.org are the calendars of the Western world and of the mainstream Jews.


Roman Years

The Roman calendar is the calendar in common usage in the Western world today. It is a solar calendar with no correlation to the movements of the moon; it is based on the calendar established by Julius Caesar in 46 BC. Augustus Caesar later borrowed a day from the month of February to make the month named after him just as long as the one named after Julius. He also rearranged the lengths of the three months after August. With these slight modifications by Augustus Caesar, the 365¼‑day Julian calendar continued in use without further modifications until the time of Pope Gregory XIII. The Gregorian calendar, established by Pope Gregory in October 1582, adjusted the calendar to stabilize the dates of the equinoxes and solstices, and to compensate for the 10‑day drift of the vernal equinox away from the date on which it had occurred in the year of the Nicene Council (325 AD). Gregory’s revised calendar was readily accepted by the Catholic European nations, but was met with resistance elsewhere. The Germanic states finally accepted it in 1700. It was adopted by the English in 1752, by the Russians in 1918, by the Greek Orthodox Church in 1923, and by the Turks in 1928.


The Roman calendar on this web site is the Gregorian calendar from 1582 to the present and beyond. Prior to 1582, it is the Augustan version of the Julian calendar. In other words, it is not accurate for dates in Protestant countries from 1582 until they changed to Gregorian counting. Nor is it accurate for any time before the reign of Augustus Caesar (r. 27 BC–14 AD). (The calendar of Julius Caesar was only slightly different than what you will find here. Prior to that the Roman calendar varied greatly, and any “Roman” dates illustrated for such years are purely hypothetical.)


Hebrew years

The Hebrew calendar begins the counting of years (with year 1 AM) in the autumn of 3761 BC. Years evenly divisible by seven (such as year 5775, which begins in September of 2014) are regarded as Sabbatical land rest years. This numbering system has been attributed to the Seder Olam Rabbah of Rabbi Jose ben Halafta (c.160 AD). The AM designation stands for anno mundi (Latin for "in the year of the world"), indicating that the years were counted from creation. However, the Seder Olam chronology and hence the AM dates are off by about 160 years because the Seder Olam shrinks the Persian period to allow for an erroneous application of the seventy weeks prophecy. (The rabbis, in denial of Jesus as the Messiah, applied the seventy weeks (490 years) to the interval between the destructions of the first and second Jerusalem temples — instead of to the time from Ezra through Jesus.)


The “Hebrew” years shown on this web site match the Rabbinic calendar which has been in use by the majority of the Jews at least since the writing of Maimonides’ Mishneh Torah (1170‑1180 AD). (See http://en.wikipedia.org/wiki/Hebrew_calendar and related articles). This is a calculated calendar, with the beginnings of months and years established by Rabbinic rules for computation and “postponements” of new moons. The calculations result in months and years that approximate, but are not in complete harmony with the natural lunar and solar cycles.


The “Hebrew” years illustrated here prior to the time of Maimonides are hypothetical, superimposing the Rabbinic computations backward in time through 142 AD. Prior to 142 AD the same Rabbinic methods of computation are used here, except that a change in the arrangement of leap years was made to “correct” a presumed calendar drift, thus allowing for the calculated calendar to support a Wednesday, 31 AD crucifixion of Jesus Christ. (Whether Jesus actually died in 31 AD is another story. But while astronomical evidence would allow for a Wednesday Passover that year, the current Rabbinic computations, without any adjustment, would not.)


In reality, in ancient times the beginning of months in the Holy Land was determined (weather permitting) by the actual observation of the first visible lunar crescent. With two or three reliable witnesses, the day of the new moon was “sanctified” by the Jewish leaders so that the appropriate animal sacrifices and other offerings could be made at the temple. The message of the sanctification of the day was sent far and wide by signal fires and runners to keep all of the Jews in sync with Jerusalem — so that all could worship on the days that were sanctified and proclaimed based on the sighting of the new moons in Israel — so that all would gather for worship on the actual days on which the special holy day offerings at the temple were offered. (See http://www.sacred-texts.com/jud/etm/index.htm The Mishna: Second Division: Appointed Times (Moed), Rosh Hashanah, Chapters 1 & 2).


The practice of establishing Hebrew calendar dates by calculation alone, apart from the observation of the lunar crescent, appears to date back to 358/359 AD, when Hillel II published his calculated calendar. In doing so, he abandoned the ancient practice of proclaiming holy time based on actual Mideast lunar sightings and evidence of the aviv (the ripening of the barley needed for the wave sheaf (omer) offering during the feast of unleavened bread). Hillel published the calendar calculations in response to Constantine's efforts to suppress Judaism by banning the sending of new moon and Aviv messengers.


The calculated Rabbinic calendar has long been considered “sacred” by some, assuming that its calculations and postponement rules were ancient, passed down from God, probably through Moses, or at least Ezra. But the historical evidence does not support this concept. And the Scriptures plainly say otherwise.


The astronomical information used in calculating dates for the Rabbinic calendar is ancient. The number used for the average length of time between molads (lunar conjunctions) is the same number used by Ptolemy (c. 90 – c. 168 AD) and Hypparchus (c. 190 – c. 120 BC); and it dates back to ancient Babylon (at least to 330 BC). The “Metonic cycle” (the close, but not absolutely perfect, correlation of 235 lunar months with 19 solar years) was understood in ancient Babylon as well, in the time of the Babylonian King Nabonassar (747 BC).


Daniel and his three friends, who were carried captive into Babylon in 604 BC, were chosen to serve in King Nebuchadnezzar’s palace because they were “young men… gifted in all wisdom, possessing knowledge and quick to understand… whom they might teach the language and literature of the Chaldeans… God gave them knowledge and skill in all literature and wisdom… They served before the king. And in all matters of wisdom and understanding about which the king examined them, he found them ten times better than all the magicians and astrologers who were in all his realm” (Daniel 1:4,17,19‑20). The “literature of the Chaldeans” included extensive astronomical diaries. Although some of them included comments about how certain astronomical phenomena were viewed as omens, these diaries were primarily records of science and history, not astrology. So we might speculate that Daniel and his friends may have been schooled in the knowledge of astronomy and could have contributed to the Babylonian database of eclipse records and to the understanding of the average month length that was computed from those records.


But the knowledge of the lunar-solar cycles and of the average length of time between lunar conjunctions was only a tool. It was not used to replace lunar sightings. The Babylonians were far too much in awe of the heavens for that.


The Jews knew that God “made the moon for seasons” (Psalms 104:19, Dby; compare Genesis 1:14), that is, for the determination of the appointed times of God’s feasts. The Hebrew word for “seasons” in these verses is mow‘edim, which means “appointed times” or “feasts”. That is how it is translated in Leviticus 23:4: “These are the feasts [mow‘edim] of the LORD, holy convocations which you shall proclaim at their appointed times [mow‘edim].”


Evidence in Jewish history is that the calendar, as long as the Jews lived in the Holy Land (both before and after the captivity), was not defined by calculation. Calculations were indeed made. But the Jewish writings say that the purpose of making calculations was to establish whether the witnesses of the visible new moons were fibbing — not to determine when months and years began. The “calendar” that was held sacred by both the Jews and the Babylonians was the one determined by the clock in the sky, not one created by the calculations of men.


It was the Roman Empire that set about to change the “times” of the calendar (Daniel 7:25), not the Babylonians. And it was during the Roman Empire that the determination of the Jewish calendar on the basis of crescent new moon sightings was suppressed.


The vast majority of the Jews keep their holy days according to the calculated “Hebrew” calendar illustrated on this web site, but a small number (such as the Karaites) have returned to the ancient practice of observing new moons from the Holy Land. As we look for the coming Messiah and the restoration of all things, we anticipate a time when all of the Jews (and all of the other descendants of Israel as well — yes, even the whole world) will do likewise.





‘And it shall come to pass that from one New Moon to another, and from one Sabbath to another, all flesh shall come to worship before Me,’ says the LORD” (Isaiah 66:23).

“Thus saith Jehovah: ‘Stand in the ways and see, and ask for the ancient paths, which is the good way, and walk therein, and ye shall find rest for your souls’ ” (Jeremiah 6:16, Dby).








Highlighted Dates

(printer‑friendly pdf version)


All the days on which special offerings were established in God’s law (in addition to the daily and weekly offerings) are highlighted in yellow on these calendars. Highlighted in blue are additional festivals and fast days mentioned in the Bible — days voluntarily set aside by the Jews in commemoration of events in their national history. Scriptural references to these dates are listed below (with festival scroll readings in italics).


Please note that the highlighted dates follow the calculated Rabbinic calendar. The alternative Hebrew calendar, the Karaite calendar, which is determined by the observations of aviv barley and crescent new moons in Israel, often differs by a day or two, and sometimes by a month, from what is illustrated.





Days of Offerings Commanded in Scripture

(over and above the daily and weekly offerings)


“You also, as living stones, are being built up a spiritual house, a holy priesthood, to offer up spiritual sacrifices acceptable to God through Jesus Christ… you are a chosen generation, a royal priesthood, a holy nation, His own special people, that you may proclaim the praises of Him who called you out of darkness into His marvelous light” (1 Peter 2:5,9).


“I beseech you therefore, brethren, by the mercies of God, that you present your bodies a living sacrifice, holy, acceptable to God, which is your reasonable service. And do not be conformed to this world, but be transformed by the renewing of your mind, that you may prove what is that good and acceptable and perfect will of God” (Romans 12:1‑2).


Day of Passover Sacrifice (Nisan/Aviv 14)

& Seven-Day Feast of Unleavened Bread (Nisan/Aviv 15‑21)

(Genesis 19:3) Exodus 10:24–15:21; 23:14‑19; 34:18‑20,23‑26; Leviticus 23:4‑8; Numbers 9:1‑5; 28:16‑25; 33:1‑5; Deuteronomy 15:19–16:8,16‑17; Joshua 5:10–6:27; 1 Samuel 1:3; 1 Chronicles 23:27‑32; 2 Chronicles 8:12‑15; ch. 29; 31:2‑3; 34:13–35:19; 2 Kings 22:1‑2; 23:21‑23; Ezra 6:19‑22; Ezekiel 45:21‑24; Luke 2:41‑52; John 2:13‑25; 6:1‑7:1; Matthew 26‑28; Mark 14‑16; Luke 22‑24; John 11:55‑20:31; Acts 12:1‑19; 20:6; 1 Corinthians 5 (v.7‑8); 11:17‑34; Hebrews 11:28‑31

Unleavened Bread reading: Song of Solomon

Second Passover (Iyar 14, 15‑21): Numbers 9:6‑14; 2 Chronicles 30


Day of Wave Sheaf Offering (the Sunday during the Feast of Unleavened Bread)

& Feast of Weeks (7th Sunday after the Unleavened Bread feast)

Exodus 19–20; 23:14‑17,19; 34:22‑24,26; Leviticus 2:12‑16; 23:9‑21; Numbers 28:26‑31; Deuteronomy 16:9‑12,16‑17; Joshua 5:10‑12; 2 Chronicles 8:12‑15; 15:10‑15; 31:2‑3; Nehemiah 10:32‑33; Ezekiel 45:16‑17; Acts 2; 20:16; 1 Corinthians 16:8; Hebrews 12:18‑29

Pentecost reading: Ruth


Feast of Trumpets (Tishri 1)

Leviticus 23:23‑25; Numbers 10:1‑10; 29:1‑6; Joel 2; Zephaniah 1:14; Psalm 81 (Genesis 41:46); Psalms 98; 150; Ezra 3:1‑3,6; Nehemiah 7:73–8:12; 1 Chronicles 23:27‑32; 2 Chronicles 2:3‑4; Matthew 24:31; 1 Corinthians 15:51‑58; Hebrews 1:10; 4:1; ch.8–9; 10:7; 11:15


Day of Atonement (Tishri 10) 

Exodus 30:10; Leviticus 16; 23:26‑32; 25:8‑55; Numbers 29:7‑11; Acts 27:9; Romans 5:8‑11; Hebrews 9:7


Seven-Day Feast of Tabernacles (Tishri 15‑21)

& The Eighth Day (Tishri 22)

Exodus 23:14‑17; 34:22‑24; Leviticus 23:33‑44; Numbers 29:12‑40; Deuteronomy 16:13‑17; 1 Chronicles 23:27‑32; 2 Chronicles 2:3‑4; ch.5‑7 (7:8‑9); 1 Kings 8; 2 Chronicles 8:12‑15; 31:2‑3; Ezra 3:4‑5; Nehemiah 8:13‑18; 10:32‑33; Ezekiel 45:25; Haggai 2:1

Tabernacles reading: Ecclesiastes


New Moons

Genesis 8:5,13; Exodus 40:2,17; Leviticus 23:24; Numbers 1:1,18; 28:11‑15; 33:38; Deuteronomy 1:3; 1 Samuel 20; 1 Chronicles 23:27‑32; 2 Chronicles 2:4; 8:12‑15; 2 Kings 4:23; 2 Chronicles 29:17; 31:2‑3; Isaiah 1:10‑20; 66:23; Ezekiel 26:1; 29:17; 31:1; 32:1; 45:17‑19; 46:1‑7; Hosea 2:11; Amos 8:4‑10; Haggai 1:1; Ezra 3:5; 7:9; 10:16‑17; Nehemiah 10:32‑33; Colossians 2:16








Jewish National Observances

(Festivals and fast days mentioned in the Bible commemorating events in Jewish history.)


Fast of the 4th month  (observed on Tammuz 17*)

Commemorates the breach made by the Babylonians in the wall of Jerusalem in the summer of 587 or 586 BC, and the subsequent capture of Zedekiah, Judah’s last king: 2 Kings 25:3‑7; Jeremiah 39:2‑7; 52:6‑11. This led to the deportation of Jews to Babylon a few weeks later. (See also Zechariah 7–8; Isaiah 58.)

In Zechariah 8:19, this Jewish fast day and others like it were prophesied to become days of joy and gladness. (Interestingly, July 4, 1776 was on Tammuz 17.)


Fast of the 5th month  (observed on the 9th of Av*)

Commemorates the destruction of the temple in Jerusalem in 587 or 586 BC and again in 70 AD:  2 Kings 25:8‑21; Jeremiah 52:12‑13; Ezekiel 20:1; Zechariah 7:3‑5; 8:19

Festival scroll reading: Lamentations


Fast of the 7th month  (the fast of Gedaliah on Tishri 3*)

Commemorates the assassination of Gedaliah (the governor of Judah appointed by Nebuchadnezzar) in 587 or 586 BC:

2 Kings 25:22‑26; Jeremiah 40‑43; 41:1; Zechariah 7:5; 8:19


Feast of Dedication  (Hanukkah – Kislev 25 through Tebet 2 or 3)

This eight‑day Festival of Lights commemorates the 165 BC Jewish Maccabean victory over the Syrians, and the rededication of the temple in Jerusalem three years after it had been defiled by Syrian idolatry: John 10:22.  (The conception of Christ in the womb of the virgin Mary appears to have occurred at the time of this feast – Luke 1:5,23‑38. See also Haggai 2:10,18,20.)


Fast of the 10th month  (Tebet 10*)

This fast is kept as a memorial of the day when Nebuchadnezzar began his 1½‑year siege against Jerusalem (in c. “January” of 588 or 587 BC) which ended with the destruction of the temple and the exile of the Jews to Babylon: 

2 Kings 25:10; Jeremiah 39:1; 52:4; Ezekiel 24:1‑2; Zechariah 7–8; 8:19


15th of Shebet 

According to the Talmud, this is the “New Year of the Trees” – the date from which the tithing year of fruit trees is calculated.  In modern Israel it is an “Arbor Day”, a day for planting trees. This date is not highlighted on the calendar, but is included here as a matter of interest.


Fast of Esther (Adar 13*)  &  Purim (Adar 14‑15)

These days commemorate the fasting (Esther 3:12‑15; 4:16; 9:31) and subsequent victory of the Jews against the plotting of Haman the Agagite (c. 473 BC):

Esther 8:9‑14; 9:1‑2,20‑22

Festival scroll reading for Purim: Esther



*With the exception of the Day of Atonement, whenever a fast day falls on the seventh day of the week, its observance is shifted to maintain the holiness of the Sabbath day. (This is in accord with the Scriptural admonition and example found in Nehemiah 8:9‑12; 9:1). If a fast day occurs on a Saturday, it is postponed to Sunday except for the Fast of Esther, which is moved back to Thursday due to Purim.