The Hebrew (or Jewish) calendar attempts to simultaneously maintain alignment between the months and the seasons and synchronise months with the Moon—it is thus deemed a “luni-solar calendar”. In addition, there are constraints on which days of the week on which a year can begin and to shift otherwise required extra days to prior years to keep the length of the year within the prescribed bounds. This isn’t easy, and the computations required are correspondingly intricate.
Years are classified as common (normal) or embolismic (leap) years which occur in a 19 year cycle in years 3, 6, 8, 11, 14, 17, and 19. In an embolismic (leap) year, an extra month of 29 days, “Veadar” or “Adar II”, is added to the end of the year after the month “Adar”, which is designated “Adar I” in such years. Further, years may be deficient, regular, or complete, having respectively 353, 354, or 355 days in a common year and 383, 384, or 385 days in embolismic years. Days are defined as beginning at sunset, and the calendar begins at sunset the night before Monday, October 7, 3761 B.C.E. in the Julian calendar, or Julian day 347995.5. Days are numbered with Sunday as day 1, through Saturday: day 7.
The average length of a month is 29.530594 days, extremely close to the mean synodic month (time from new Moon to next new Moon) of 29.530588 days. Such is the accuracy that more than 13,800 years elapse before a single day discrepancy between the calendar’s average reckoning of the start of months and the mean time of the new Moon. Alignment with the solar year is better than the Julian calendar, but inferior to the Gregorian. The average length of a year is 365.2468 days compared to the actual solar tropical year (time from equinox to equinox) of 365.24219 days, so the calendar accumulates one day of error with respect to the solar year every 216 years.
* The Hebrew Calendar runs from Sundown to Sundown. If birth occured after Sundown, use the next Civil Calendar day.
What can you do with a Date Converter? Plenty!
Find out what day your Jewish birthday is! Say you were born on May 8, 1970 (before sundown…see below). Pull down 1970, May and 8 for the secular date. Your Hebrew birthday is on 2 Iyyar, 5730! Keep going…want to find out when to celebrate your Jewish birthday in 2004? On that same Hebrew date, change the year to 5764. This year, your Jewish birthday falls out on April 23, 2004!
Figure out Yarzheits of loved ones who have passed away. Figure out when Jewish holidays will fall in future years….no more calendar conflicts!
According to the Jewish lunar calendar, the day begins the evening before…the actual Jewish day starts with sundown of the previous day. So if you were born after sundown on a particular day, your Jewish birthday falls out on the following day, i.e. if you were born at 9:00PM on December 3, 1959, your Jewish birthday is the 3rd day of Kislev, not the 2nd. If you were born before sundown on December 3, your birthday would be on the 2nd of Kislev.
The Jewish year of 5764 corresponds to the secular years of 2010-2011. So we are currently in the 58th Jewish century, which spans 1939-2039. If you are looking for secular dates before 1939 or after 2039, you need to change the century on the Date Converter.
From creation to the year 10,000 – For years prior to 5700 (1939 civil), simply change the century value.