About the Hebrew Date Converter
This Hebrew date converter translates a Gregorian (civil) date into the Hebrew calendar — day, month and year Anno Mundi — and converts a Hebrew date back to the Gregorian calendar. It handles the 19-year leap cycle with its extra month of Adar II, the variable lengths of Cheshvan and Kislev, and the postponement rules that keep Rosh Hashanah off certain weekdays.
Use it to find your Hebrew birthday for a bar or bat mitzvah, to work out the Gregorian date of a yahrzeit (memorial anniversary), to schedule events around Jewish holidays, or simply to see today’s date on the Jewish calendar. Results also show whether the Hebrew year is a leap year, how many days it has, and when that year’s Rosh Hashanah and Passover fall.
A Hebrew calendar day begins at sunset, not midnight. If an event happened after sunset, tick “after sunset” so the converter moves to the next Hebrew date. The calculation uses the fixed arithmetic rules of the modern Hebrew calendar (Hillel II), so it gives the standard dates printed in Jewish calendars worldwide.
How to use the hebrew date converter
- 1Choose whether to convert Gregorian → Hebrew or Hebrew → Gregorian.
- 2Enter the Gregorian date, or the Hebrew day, month and year.
- 3If the event was after sunset, switch on “After sunset”.
- 4Read the converted date, weekday and leap-year status.
- 5Use the month table to see when each Hebrew month begins that year.
Formula and method
The Hebrew calendar is lunisolar. Each month follows the mean lunar cycle of 29 days, 12 hours and 793 parts (a part is 1/1080 hour), and 7 of every 19 years get an extra month (Adar I) so that Passover stays in spring. A year is a leap year when (7 × year + 1) mod 19 is less than 7.
The converter counts the months elapsed since the epoch to find the molad (mean new moon) of Tishrei, then applies the dechiyot postponement rules so that Rosh Hashanah never falls on Sunday, Wednesday or Friday and year lengths stay within 353–355 or 383–385 days. Cheshvan and Kislev absorb the difference. Dates are counted as day numbers (Rata Die) and translated to and from the Gregorian calendar, following Reingold and Dershowitz’s Calendrical Calculations.
- y
- Hebrew year Anno Mundi (e.g. 5787)
- p
- Parts (chalakim): 1,080 parts = 1 hour
Worked examples
September 29, 2026 on the Hebrew calendar
Rosh Hashanah 5787 fell on Saturday, September 12, 2026, so September 29 is the 18th of Tishrei — during Sukkot. 5787 is a leap year with 13 months and 385 days.
Purim 2024 (a leap year)
In leap years Purim is celebrated on 14 Adar II. In 5784 that was Sunday, March 24, 2024. The year had 383 days, the shortest possible length for a leap year.
First day of Hanukkah 5786
25 Kislev 5786 is Monday, December 15, 2025. Because Hebrew days start at nightfall, the first candle is lit on the evening of Sunday, December 14.
Passover eve after sunset
After sunset on April 1, 2026 the Hebrew date is already 15 Nisan 5786, the first day of Passover — which is why the first Seder is held that evening. The daytime of 15 Nisan is April 2.
Frequently asked questions
How do I find my Hebrew birthday?+
Enter your Gregorian date of birth. If you were born after sunset, switch on “After sunset”, because the Hebrew day had already moved on. The result is your Hebrew birthday; convert it back for any future year to find when to celebrate.
What year is it on the Hebrew calendar?+
The Hebrew year 5787 began at Rosh Hashanah on September 12, 2026 and runs until Rosh Hashanah 5788 on October 2, 2027. Hebrew years count from the traditional date of creation (Anno Mundi).
Why does the Hebrew calendar have leap years?+
Twelve lunar months are about 11 days shorter than a solar year. To keep festivals like Passover in spring, 7 years in every 19-year cycle add a 13th month, Adar I, so the leap year has Adar I and Adar II.
Why do Jewish holidays start the evening before?+
In the Hebrew calendar a day runs from sunset to sunset, following Genesis (“there was evening and there was morning”). So a holiday dated 15 Nisan begins at sunset on the previous Gregorian day.
In a leap year, which Adar is used for a birthday or yahrzeit?+
Purim is celebrated in Adar II. Customs differ for birthdays and yahrzeits of people born or deceased in a regular Adar: many use Adar II for bar/bat mitzvahs and Adar I or both for yahrzeits. Ask your rabbi for your community’s custom.