This Hebrew calendar date converter translates any Gregorian (civil) date into the Hebrew calendar and back again, showing the weekday, leap-year status, and month lengths used in the traditional Jewish lunisolar calendar.
Pick a tab depending on the direction you need. For "Gregorian → Hebrew," choose any civil calendar date and click convert to see the equivalent Hebrew year, month, and day. For "Hebrew → Gregorian," enter a Hebrew year, then choose the month and day (the day list automatically adjusts for 29- or 30-day months) and click convert to see the matching civil date, weekday, and leap-year information.
The Hebrew calendar governs Jewish holidays, Torah readings, yahrzeits (memorial anniversaries), and Bar/Bat Mitzvah dates, all of which shift relative to the Gregorian calendar every year because Hebrew months follow the moon while the year is anchored to the solar seasons. Genealogists tracing family records from Eastern Europe, historians dating rabbinic responsa or ketubot (marriage contracts), and anyone planning a Passover seder or Rosh Hashanah dinner needs a reliable way to move between the two systems. For example, knowing that 15 Nisan always falls on the first night of Passover only helps if you can translate it into a specific Gregorian date each spring. This tool removes the guesswork by applying the same arithmetic rules used in printed Jewish calendars since the 4th century.
The Hebrew calendar is lunisolar: twelve lunar months of 29 or 30 days (about 354 days total) are periodically corrected with a leap month, Adar II, so the calendar stays aligned with the solar year. Leap years occur in years 3, 6, 8, 11, 14, 17, and 19 of a 19-year Metonic cycle — the rule is (7 × year + 1) mod 19 < 7. Each month's length depends on the "molad" (mean lunar conjunction) and postponement rules (dechiyot) that prevent Rosh Hashanah from falling on Sunday, Wednesday, or Friday. This converter implements the classical arithmetic algorithm (delay calculations, month-day tables, and Julian Day Number bridging) to move precisely between the Hebrew epoch of 3761 BCE and any Gregorian date.
The modern fixed-arithmetic Hebrew calendar was formalized around 359 CE, traditionally credited to Sanhedrin president Hillel II, replacing the earlier practice of observing new moons by eyewitness testimony and sending messengers to announce the new month across Jewish communities. Years are counted from Anno Mundi (AM), the traditional date of Creation, placed at 3761 BCE — so the Gregorian year 2025 overlaps mostly with Hebrew year 5785/5786. The calendar's 19-year Metonic cycle, which reconciles 235 lunar months with 19 solar years, was independently discovered by the Greek astronomer Meton of Athens in 432 BCE and by Babylonian astronomers even earlier, showing how ancient cultures converged on the same lunisolar solution.
Suppose you want to know the Hebrew date for October 3, 2024 (Gregorian). Converting via the algorithm: the Julian Day Number for that date is calculated first, then translated using the Hebrew delay and month-length rules. The result is 1 Tishrei 5785 — the very first day of the Hebrew year, which is Rosh Hashanah. The tool also reports that 5785 is not a leap year (12 months), that the year has 354 days (a "regular" year), and that the weekday is Thursday. Running the reverse conversion — entering Hebrew year 5785, month Tishrei, day 1 — returns exactly October 3, 2024, confirming the round-trip accuracy. The tool also shows that this date falls roughly 2,113,000 days after the traditional Creation, about the same span as 72 average human lifetimes of 80 years laid end to end.
Select the "Gregorian → Hebrew" tab, choose your date using the date picker, and click convert. The tool instantly shows the Hebrew year, month, and day, along with the weekday and whether it's a leap year.
The Hebrew year begins on 1 Tishrei (Rosh Hashanah), which usually falls in September or early October on the Gregorian calendar, so each Hebrew year overlaps two consecutive Gregorian years.
A leap year adds a 13th month, Adar II, to keep the lunar calendar synchronized with the solar seasons. This happens 7 times in every 19-year cycle, following the rule (7×year+1) mod 19 < 7.
It implements the classical fixed arithmetic rules used in printed Jewish calendars since the calendar's standardization around 359 CE, so it matches published Hebrew calendars for any year, ancient or modern.
No — Hebrew days begin at sunset. This converter reports the civil (daytime) equivalent date, which is the convention most calendars and software use for date matching.
As of late 2024–2025 CE, the Hebrew calendar is in year 5785, counted from the traditional Creation date of 3761 BCE (Anno Mundi).
HistoryCalc