HistoryCal - Definition
h# Hebrew

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Calendar Description

The Hebrew calendar, also known as the Jewish calendar, is a lunisolar arithmetical calendar based on the 19 year Metonic cycle. In 7 of the 19 years, an extra month, named "Adar I" is added before "Adar" (and "Adar" is renamed "Adar II").

Prior to using the this calendar, a observational system was used, both in determining the start of the lunar month and, by using natural phenomena, in adding the intercalated month. The Metonic cycle may have used to check and confirm the observations, but it was not until Hillel II in the fourth century CE that this replaced the observational system. The rules for calculations slowly evolved until around the 9th century, when the calendar described here was formulated.

Use Case

The mathematics of the calendar is commonly attributed Hillel II in the fourth century CE. From then it slowly evolved until it reached its current form in approximately the 12th century.


Month Names
8MarheshvanCsh2930 in complete year
9KislevKsl3029 in deficient year
12AdarAdr2930 in leap year
13Adar IIAds29Leap year only
Week Names
1Yom RishonRish
2Yom SheniShen
3Yom ShelishiShel
4Yom Revi'iRevi
5Yom HamishiHami
6Yom ShishiShis
7Yom ShabbatShab

The year length is one of 353, 354, 355, 383, 384 or 385 days, and average approximately 365.24682 days. Days start at sunset, the conversion here is for midday.

Months are linked to the Lunar cycle starting near the new moon and are 29 or 30 days long.

Regular years consist of 12 months and leap years of 13 months. Leap years occur on the 3rd, 6th, 8th, 11th, 14th, 17th and 19th years of a 19 year cycle beginning in year 1.

In a common year, the months are numbered 1 to 12 In a leap year an additional 30 day month, traditionally unnumbered, is inserted between months 11 and 12. However, in this scheme, the additional month is numbered 12 and the existing 12th month is renumbered 13. The length of each month is shown in the given table.

The length of a nominal regular year or leap year is 354 or 384 days, the length of a complete year is 355 or 385 days whilst that of a deficient year is 353 or 383 days.

In both common and leap years, the year count in increased on the 1st day of the 7th month.

The New Year (the day the year count is increased) occurs on the 1st day of the 7th month.

The calendar is also linked to the 7 day week, with the days numbered 1 to 7, and with Sunday equal to day 1.

The following rules are used to determine when the New Year falls and thus, the length of the year.

  1. If the time of the new moon is at midday or after then the New Year is delayed by one day.
  2. If the New Year were to fall on a Sunday, Wednesday or Friday then the New Year is delayed by one day or 2 days if combined with the previous rule.
  3. If the previous rules combine to increase the length of the following year to 356 days, the current New Year is delayed by a day.
  4. If the previous rules combine to decrease the length of the previous year to 382 days, the current New Year is delayed by a day.
The Epoch is set at


Default Script
vocab hm { name "Month names"; fieldname month; lang en; stylename Month, Mon; tokens { 1, "Nisan", "Nsn"; 2, "Iyyar", "Iyr"; 3, "Sivan", "Svn"; 4, "Tammuz", "Tmz"; 5, "Av", "Aav"; 6, "Elul", "Ell"; 7, "Tishri", "Tsh"; 8, "Marheshvan", "Csh"; 9, "Kislev", "Ksl"; 10, "Tevet", "Tvt"; 11, "Shevat", "Shv"; 12, "Adar", "Adr"; 13, "Adar II", "Ads"; } } vocab hw { name "Weekday names"; fieldname wsday; // Note: Days are numbered from Sunday, unlike "wday". lang en; stylename Weekday, WDay; tokens { 1, "Yom Rishon", "Rish"; // Sunday 2, "Yom Sheni", "Shen"; // Monday 3, "Yom Shelishi", "Shel"; // Tuesday 4, "Yom Revi'i", "Revi"; // Wednesday 5, "Yom Hamishi", "Hami"; // Thursday 6, "Yom Shishi", "Shis"; // Friday 7, "Yom Shabbat", "Shab"; // Saturday } } grammar h { optional wsday; vocabs hm, hw; alias field { WDay, wsday; Day, day; Month, month; Year, year; } alias stylename { WDay, w; Day, dd; Month, mm; Year, yyyy; } alias unit { d, day; m, month; y, year; w, week; } format dmy, "(Day) |(Month:hm) |(Year)"; format "dmy.a", "(Day) |(Month:hm.a) |(Year)"; format "dmy.d", "(Day) |(Month) |(Year)"; format wdmy, "(WDay:hw) |(Day) |(Month:hm) |(Year)"; format "wdmy.a", "(WDay:hw.a) |(Day) |(Month:hm.a) |(Year)"; format ymd, "(Year)|,(Month:hm.a)|,(Day)"; pref dmy; } scheme h { name "Hebrew"; base hebrew; grammar h; }

The Month name abreviations are those used by the GEDCOM standard version 5.5.1 Page 53 (PDF).

Note, the use of optional field "wsday" in which the week starts on Sunday (day 1).

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18th December 2014