How the Hebrew Calendar Works
Understanding the Hebrew calendar doesn’t have to be complicated. Once you know a few key principles, it becomes much easier to understand why holidays fall when they do, how Hebrew dates relate to the Gregorian calendar, and why some years include an extra month.
Whether you’re planning family celebrations, learning about Jewish traditions, or simply trying to understand a Hebrew English calendar, this guide will help you make sense of how the two calendar systems work together.
Two calendar systems, one life
For most people, everyday life follows the Gregorian calendar. Work, school, appointments, and public holidays are all scheduled by Gregorian dates.
At the same time, many families, schools, and communities celebrate holidays, anniversaries, memorial days, and other important occasions according to the Hebrew calendar. This means many people naturally live across two calendar systems.
If you’ve ever wondered why Passover falls on a different Gregorian date each year, why a Hebrew birthday doesn’t always match the same date on your wall calendar, or why some Hebrew years include an extra month, you’re asking exactly the questions the Hebrew calendar was designed to answer.
Although the two calendars measure time differently, they work together remarkably well once you understand the basic ideas behind each one.
Gregorian: solar. Hebrew: lunisolar.
Gregorian
Solar calendar
Its year is based on the Earth’s orbit around the sun, lasting approximately 365.25 days. Leap years add an extra day every four years to keep the calendar aligned with the seasons. Months have fixed lengths between 28 and 31 days and do not follow the phases of the moon.
Hebrew
Lunisolar calendar
It follows both the moon and the sun. Each month begins with the new moon and lasts 29 or 30 days, matching the lunar cycle. Twelve lunar months total only about 354 days, roughly eleven days shorter than the solar year. To keep holidays in their seasons, a leap month is added every few years; more on that below.
This is why Jewish holidays appear to “move” on the Gregorian calendar. They don’t move at all.
Passover
always 15 Nisan
Rosh Hashanah
always 1 Tishrei
Hanukkah
begins 25 Kislev
The Hebrew dates never change. Only their corresponding Gregorian dates change because the two calendars measure time differently. For anyone planning around both calendars, seeing Hebrew and Gregorian dates together makes these relationships immediately clear.
The Hebrew months
The Hebrew calendar contains twelve months during a regular year and thirteen months during a leap year. The calendar year begins with Tishrei, the month of Rosh Hashanah, although the Torah describes Nisan as the first month for religious festivals. This dual perspective is one of the unique characteristics of the Hebrew calendar.
Here’s how the months fit into the Gregorian year.
Tishrei
30 daysSeptember-October
Rosh Hashanah, Yom Kippur, Sukkot
Cheshvan
29 or 30 daysOctober-November
Length varies by year
Kislev
29 or 30 daysNovember-December
Hanukkah begins on 25 Kislev
Tevet
29 daysDecember-January
Shevat
30 daysJanuary-February
Tu BiShvat
Adar
29 daysFebruary-March
Purim. In leap years this becomes Adar I and Adar II
Nisan
30 daysMarch-April
Passover begins on 15 Nisan
Iyar
29 daysApril-May
Lag BaOmer, Yom HaAtzmaut
Sivan
30 daysMay-June
Shavuot
Tammuz
29 daysJune-July
Av
30 daysJuly-August
Tisha B'Av
Elul
29 daysAugust-September
The month preceding Rosh Hashanah
Since Hebrew months follow the lunar cycle rather than fixed solar months, they gradually shift within the Gregorian calendar while remaining perfectly consistent within the Hebrew calendar itself.
For families, educators, and communities that regularly use Hebrew dates, having both calendars displayed together removes the need to constantly convert between the two systems.
Leap years and Adar II
12 months
about 354 days
a regular year
13 months
about 384 days
a leap year adds Adar II
7 in 19
years 3, 6, 8, 11, 14, 17, 19
the Metonic cycle
A regular Hebrew year is roughly eleven days shorter than a solar year. If the calendar simply followed the moon, holidays would slowly drift through the seasons. Over time, Passover would no longer fall in the spring, and Sukkot would no longer be celebrated in the autumn.
To prevent this, the Hebrew calendar periodically adds an entire extra month. This additional month is called Adar II (or Adar Bet). Unlike the Gregorian calendar, which adds a single day every four years, the Hebrew calendar follows a fixed 19-year cycle, known as the Metonic cycle.
During a leap year, the single month of Adar becomes two separate months: Adar I (30 days) and Adar II (29 days). Purim is celebrated during Adar II, ensuring the holiday remains in the proper place within the yearly cycle.
Although the rules behind leap years are fascinating, they don’t need to be something you calculate yourself. A well-designed Hebrew calendar automatically places holidays, birthdays, anniversaries, and memorial dates on the correct Hebrew date, whether the year has twelve months or thirteen.
How to read a Hebrew date
Hebrew dates follow a straightforward format: day, then month, then year.
15
Day
Nisan
Month
5787
Year
Unlike Gregorian dates, where many people write month before day, Hebrew dates always place the day first.
The Hebrew calendar counts years from the traditional date of creation. While there isn’t a simple one-to-one conversion between Hebrew and Gregorian years, a useful approximation is:
Before Rosh Hashanah
subtract 3760
After Rosh Hashanah
subtract 3761
For example, Hebrew year 5787 corresponds roughly to 2026-2027 on the Gregorian calendar.
You don’t need to memorize these conversions to use the calendar. Once both date systems are displayed together, reading Hebrew dates quickly becomes second nature.
When does the day begin?
Gregorian calendar
A new day begins at midnight
Hebrew calendar
A new day begins at sunset
This is why Jewish holidays begin on what appears to be the evening before their Gregorian date. For example, when Shabbat candles are lit on Friday evening, it is already Saturday according to the Hebrew calendar. The same principle applies to every Jewish holiday.
This distinction becomes especially important when converting dates. An event that takes place after sunset is still the same Gregorian day, but it already belongs to the following Hebrew date.
Understanding this difference helps explain why some online date converters, printed calendars, or event schedules appear to disagree. They’re often referring to different moments in the transition between the two calendar systems.
A bilingual calendar that displays both dates together makes these transitions easy to understand without needing to perform the conversion yourself.
Why use a Hebrew English calendar?
Once you understand how the Hebrew calendar works, the next challenge is using it in everyday life. Most people still organize work, school, appointments, and travel using Gregorian dates. At the same time, holidays, yahrzeits, Hebrew birthdays, anniversaries, and community events are often remembered according to the Hebrew calendar.
A Hebrew English calendar shows both systems on every day, so nothing needs converting. Instead of checking conversion websites or counting months manually, you can immediately see both the Hebrew and Gregorian date for every day of the year.
Families
Birthdays, anniversaries, holidays, and personal milestones together in one place.
Educators
School events alongside holidays, so students and parents see the full picture at a glance.
Communities
A shared calendar that respects both everyday scheduling and important religious and cultural dates.
Most importantly, it allows you to think about your year as one complete picture instead of two separate timelines.
Build your own Hebrew English calendar
Understanding how the Hebrew calendar works is the first step. The next is seeing it in a way that’s practical for everyday life.
With CultureSync, you can create a personalized printable calendar that displays Hebrew and Gregorian dates side by side, choose the holidays you observe, add birthdays, anniversaries, memorial days, and personal events, then customize the design to match your style.
When you’re finished, download a beautiful print-ready PDF for your wall or a one-time calendar file that you can add to your preferred calendar app.
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