How to Convert a Secular Date to the Jewish Calendar

Calculating dates is easy

The easiest way to convert a secular date to the Jewish calendar (and vice versa) is with a free online calendar converter (link provided below). The Jewish calendar is based on the lunar cycle, which generates a year of only 354-355 days. The Bible, however, refers to Passover as "the holiday of spring," (Deuteronomy 16:1) so the calendar is adjusted so that it always falls during the secular months of March or April. The Jewish calendar therefore adds a leap month on a periodic basis in order to keep the holidays aligned with the appropriate seasons.

Things You'll Need

• calendar
• online calendar calculator

Instructions

Converting secular dates

1. Take the secular year and add 3760 to find the Jewish year. Note that this quick-and-dirty calculation will work for dates between January and September; anytime after that you might have to add 3761 because the Jewish New Year (Rosh Hashanah) comes in the fall. You can skip this step if you are using the online calculator (see step 2).

2. The easiest way to get the specific month and day of the week is to use an online calendar converter, such as hebcal.com (link below). Simply click on "Hebrew Date Converter," enter the secular (Gregorian) date, and that's it. You can also use the same page to convert Jewish dates to the secular calendar.

3. 

   Before or after sunset?

   Don't forget to click the box labelled "after sunset" (if appropriate). This is because Jewish days begin at sunset, not dawn, a practice derived from the Biblical description of creation, "and it was evening and it was morning" (see Genesis 1). If you're trying to figure out something related to a birthday--the right date for a Bar Mitsvah, for example--you should determine whether the birth took place after sunset or not, because the birthday of a child born after sunset is calculated as the date of the following morning.

Tips & Warnings

• If the date you're converting falls in the leap month (Adar II), many specific rules apply to Jewish observances on that date. Consult your local Rabbi for more guidance.

References

• Judaism 101: "Jewish Calendar"

Resources

• Hebcal.com: Jewish Calendar Tools
• "The Comprehensive Hebrew Calendar," Arthur Spier,1986