Hebrew birthday calculator / The Hebrew calendar
The Hebrew calendar, explained
Why your Hebrew birthday lands on a different English date every year, and the few rules behind it.
Months follow the moon
The Hebrew calendar has twelve lunar months of 29 or 30 days. A common year is about 354 days, roughly 11 days shorter than the 365-day English year. That's why a Hebrew date drifts earlier on the English calendar from one year to the next.
A 13th month keeps it in step with the seasons
To stop the festivals drifting through the seasons, an extra month is added in seven of every nineteen years: years 3, 6, 8, 11, 14, 17 and 19 of the cycle. In those leap years Adar is doubled: Adar I (30 days) is added before Adar II (29 days), and the Hebrew date jumps later again on the English calendar.
The next 19 Hebrew years, starting with the year that began in September 2026:
Source: Wikipedia, "Hebrew calendar" (opens in a new tab) · checked 4 Oct 2026
The months and their lengths
- Nisan30 days
- Iyar29 days
- Sivan30 days
- Tammuz29 days
- Av30 days
- Elul29 days
- Tishrei30 days
- Cheshvan29 or 30 daysvaries by year
- Kislev30 or 29 daysvaries by year
- Tevet29 days
- Shevat30 days
- Adar I30 daysleap years only
- Adar (Adar II)29 days
Months listed from Nisan, as the Torah counts them; the year number changes at Rosh Hashanah, 1 Tishrei. Cheshvan and Kislev each gain or lose a day in some years, so a common year has 353, 354 or 355 days and a leap year 383, 384 or 385.
Source: Wikipedia, "Hebrew calendar" (opens in a new tab) · checked 4 Oct 2026
The day starts at sunset
A Hebrew day runs from sunset to the next sunset. A baby born on a Tuesday evening after sunset was born on Wednesday's Hebrew date. That's what the calculator's Born after sunset switch does, and it changes the Hebrew birthday, and the bar or bat mitzvah date, for life.
If a birth was close to sunset, check the exact sunset time for that place and day before choosing, and ask your rabbi if it was in the period between sunset and nightfall.
Source: Wikipedia, "Hebrew calendar" (opens in a new tab) · checked 4 Oct 2026
What this means for your birthday
- Your Hebrew birthday is the same Hebrew day and month each year, on a different English date.
- Born on the 30th of Cheshvan, Kislev or Adar I? Some years don't have that day. See Born in Adar or on the 30th.
- Born in Adar? Leap years have two. The same page explains which one the calculator uses.
Work out your own dates
The Hebrew date, the bar or bat mitzvah date, the parsha and the next 20 Hebrew birthdays, from one English date.
