Hebrew birthday calculator / Bar and bat mitzvah dates
How the bar or bat mitzvah date is set
Four steps from a birth certificate to a date for the synagogue, and the cases where you should ask your rabbi.
- 1
Find the Hebrew birth date
Convert the English birth date, remembering that a birth after sunset belongs to the next Hebrew day.
- 2
Add 13 years, or 12
In Orthodox communities boys become bar mitzvah at 13 and girls bat mitzvah at 12. Reform, Conservative and Reconstructionist communities use 13 for both.
- 3
Find that Hebrew date on the English calendar
The same Hebrew day and month in the 13th (or 12th) year. A boy becomes bar mitzvah at nightfall as that day begins, whatever time of day he was born.
- 4
Choose the celebration
The ceremony is usually held on the first Shabbat after the birthday. In Orthodox settings it is sometimes held at a Monday or Thursday morning service, when the Torah is read.
Sources: Wikipedia, "Bar and bat mitzvah" (opens in a new tab); Chabad.org, "The Laws of Bar Mitzvah" (opens in a new tab) · checked 4 Oct 2026
When the date needs a second look
- Born after sunset. The Hebrew birthday is the next day, so the bar or bat mitzvah is too. Tick "Born after sunset" in the calculator.
- Born in Adar, bar mitzvah in a leap year. Chabad.org's summary of the laws says a boy born in Adar of a regular year becomes bar mitzvah in Adar II, and notes that some authorities hold Adar I, so he puts on tefillin from his Adar I birthday.
- Born in Adar of a leap year, bar mitzvah also in a leap year. The same summary says it's on the date he was actually born: Adar I or Adar II.
- Born on 30 Cheshvan or 30 Kislev. If the bar mitzvah year has no such day, the same summary gives 1 Kislev or 1 Tevet.
The calculator follows these where it can and shows a note on the result. For the date you'll actually book, confirm with your rabbi. More detail: Born in Adar or on the 30th.
Source: Chabad.org, "The Laws of Bar Mitzvah" (opens in a new tab) · checked 4 Oct 2026
The parsha
The calculator also shows the Torah portion read on the Shabbat after the birth. Families often look at it when choosing what the child will learn, but the portion read at the bar or bat mitzvah itself is the one of that week, which the synagogue will confirm.
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.
