Jewish Calendar and Date Calculator

The Jewish calendar follows what is known as the lunisolar year. Expressed in terms of the globally used Gregorian calendar, it goes back to the year 3761 before the current era (BCE). According to the Jewish calendar, we are thus already in the sixth millennium. The Jewish new year is in the month of Tishri (September or October) and is marked by Rosh Hashanah, the Jewish new year festival.

Differences to the Gregorian calendar

There are various aspects of the Jewish calendar that distinguish it from the Gregorian one. According to the former, for example, a day does not begin at midnight, but at the onset of dusk, and ends at the same time the next day. In a lunisolar year, months are calculated by the moon, while the year is linked to the rhythm of the sun. A Jewish month therefore always begins with the new moon. In line with the moon’s orbit, a month can consist of 29 or 30 days. As a result, a lunar year is ten or more days shorter than its solar counterpart with its 365 days. To make up for this difference, leap years consisting of 13 months are added in the Jewish calendar. Owing to these different means of calculation, discrepancies between Jewish and Gregorian days and dates are constantly shifting.

Date calculator

There is thus no simple basis for converting dates, and any such calculation can pose a challenge. To simplify the task, the SIG has made a user-friendly date calculator available that allows conversion from a Gregorian to a Jewish date and vice versa.