Hebrew Calendar Converter

The Hebrew Calendar Converter turns any date between the Western (Gregorian) calendar and the Hebrew (Jewish) calendar into a clear, side-by-side answer — and adds the Hebrew month name, the date written in traditional Hebrew gematria letters, the weekday in Hebrew, the leap-year (Adar I and Adar II) and Shabbat flags, the year-length type, the Jewish holiday landing on that day, and a live countdown to the next Rosh Hashanah, Hanukkah, Passover and Yom Kippur. The conversion is fully bi-directional, instant, and needs no sign-up.

What is the Hebrew (Jewish) calendar?

The Hebrew calendar is a lunisolar calendar: its months follow the cycles of the Moon while its years are kept aligned with the solar seasons. Each month begins near the new moon and is 29 or 30 days long, so twelve lunar months total about 354 days — eleven days short of the solar year. To stop the festivals from drifting through the seasons, a thirteenth leap month is inserted seven times in every nineteen-year (Metonic) cycle. Years are counted from the traditional date of Creation, Anno Mundi ("in the year of the world", abbreviated AM), which is why the civil year 2025-2026 CE corresponds to the Hebrew year 5786.

How to use the converter

• Pick a direction. Toggle between 📅 Gregorian → ✡ Hebrew (start from a Western date) and ✡ Hebrew → 📅 Gregorian (start from a Jewish date). The form switches automatically and a live preview updates as you type.
• Enter the date. For Gregorian to Hebrew, choose the calendar date. For Hebrew to Gregorian, enter the Hebrew year (AM), pick the month from the list (English plus Hebrew), and enter the day (1–29 or 30). In a leap year the month list automatically adds Adar II.
• Convert. Press the Convert button to lock in the full result below the form.
• Read the result. The hero card shows the two dates side by side, including the date in Hebrew letters. Below it you get the month name and its meaning, the weekday in Hebrew, the leap-year, year-type and Shabbat flags, any holiday on that day, a countdown to the next major festivals, and a visual grid of the whole month.

The months of the Hebrew year

Months are listed here starting from Tishrei because the civil year and year-numbering begin there, even though Nisan is counted as month 1 in the Torah. Cheshvan and Kislev can each be 29 or 30 days depending on the length of the year, which is what gives the calendar its Deficient (353/383), Regular (354/384) and Complete (355/385) year types.

Major dates on the Jewish calendar

• 1 Tishrei — Rosh Hashanah, the Jewish New Year
• 10 Tishrei — Yom Kippur, the Day of Atonement
• 15 Tishrei — Sukkot, the Feast of Tabernacles
• 25 Kislev — Hanukkah, the Festival of Lights (eight days)
• 15 Shevat — Tu BiShvat, the New Year of the Trees
• 14 Adar — Purim (in Adar II during a leap year)
• 15 Nisan — Passover (Pesach)
• 18 Iyar — Lag BaOmer
• 6 Sivan — Shavuot, the Feast of Weeks
• 9 Av — Tisha B'Av, a day of mourning

How the calculation works

This converter uses the fixed arithmetic Hebrew calendar codified by Hillel II in the 4th century CE — the same rules followed by Jewish communities worldwide. The leap years of each nineteen-year cycle are years 3, 6, 8, 11, 14, 17 and 19, in which the extra month Adar I is added. The exact start of each year is set by calculating the molad (the average new moon of Tishrei) and then applying the four dehiyyot (postponement rules) that keep certain festivals off forbidden weekdays. Internally the tool converts each calendar to and from the Julian Day Number, a continuous count of days, which makes the conversion exact and reversible in either direction.

Reading a Hebrew date written in letters

Traditionally, Hebrew dates are written with letters rather than digits, using gematria, in which each letter has a numeric value (א = 1, י = 10, ק = 100, and so on). The converter prints both forms. Two conventions are worth knowing: the thousands of the year are usually dropped, so 5786 is written תשפ״ו (786) rather than spelling out the 5,000; and the numbers 15 and 16 are written ט״ו and ט״ז instead of the expected combinations, to avoid writing letter-pairs that spell part of a divine name. A geresh (׳) marks a single letter and gershayim (״) appears before the last letter of a multi-letter number.

A note on sunset and accuracy

The Jewish day begins at sunset, not midnight. This converter maps a Gregorian calendar date to the Hebrew date that covers most of its daylight hours; the same Hebrew date actually began the previous evening. For a holiday, that means the observance starts at sundown on the evening before the Gregorian date shown. The arithmetic conversion itself is exact and matches printed Jewish calendars; use this tool for birthdays, yahrzeits, anniversaries, historical research and planning.

Worked examples

• Gregorian → Hebrew: September 23, 2025 converts to 1 Tishrei 5786 AM (א׳ תִּשְׁרֵי תשפ״ו) — Rosh Hashanah, the Jewish New Year.
• Gregorian → Hebrew: April 23, 2024 converts to 15 Nisan 5784 AM (ט״ו נִיסָן תשפ״ד), the first day of Passover.
• Hebrew → Gregorian: 25 Kislev 5786 AM (the first day of Hanukkah) converts to December 15, 2025.
• Hebrew → Gregorian: 10 Tishrei 5787 AM (Yom Kippur) converts to its matching autumn date in 2026.

Because the Hebrew year is lunisolar, a fixed Jewish date such as 1 Tishrei lands on a different Gregorian day each year, but always within a roughly four-week window in the same season — unlike a purely lunar calendar, where it would drift through all the seasons.

Frequently asked questions

Why does the Hebrew calendar add a leap month instead of a leap day?

Because its months must stay tied to the Moon. Adding single days would break that link, so instead a whole extra lunar month (Adar I) is inserted in 7 of every 19 years. This keeps the average year close to the solar year and keeps Passover in spring and Sukkot in autumn.

What does "AM" mean?

AM stands for Anno Mundi, Latin for "in the year of the world." It counts years from the traditional date of Creation. The Hebrew year is roughly the Gregorian year plus 3760, so 2026 CE falls mostly in AM 5786.

What are Adar I and Adar II?

In a leap year the month of Adar is doubled. Adar I (Adar Aleph, 30 days) is the inserted month; the regular Adar becomes Adar II (Adar Bet, 29 days), and Purim is observed in Adar II. The converter names them correctly and only shows Adar II for leap years.

Can I convert my Hebrew birthday or a yahrzeit?

Yes. Enter any Gregorian date to find its Hebrew equivalent, or enter a Hebrew date to find the Gregorian day it falls on in a given year. Because the Jewish day begins at sunset, a birthday or yahrzeit that occurs in the evening is counted on the following Hebrew date.

Does the tool change the URL when I click a quick example?

No. Quick-example buttons only fill in the form so you can review and adjust the values before pressing Convert. Nothing is submitted until you click the Convert button.