Bar & Bat Mitzvah Date Calculator
Enter a date of birth to find the Bar or Bat Mitzvah date on the Hebrew calendar, the Shabbat on or after it, and that week’s Torah portion for Israel or the Diaspora.
2 Tamuz 5786 ב׳ תמוז ה׳תשפ״ו
- Hebrew birth date
- 2 Tamuz 5773 ב׳ תמוז ה׳תשע״ג
- Torah reading (Diaspora)
- Korach
How the date is worked out
A boy becomes Bar Mitzvah at thirteen. The Mishnah lists “at thirteen, for the commandments” among the stages of life (Pirkei Avot 5:21). The date is the thirteenth Hebrew birthday, and it begins at nightfall on the evening before. A girl becomes Bat Mitzvah at twelve, and many communities mark it then. Some celebrate a Bat Mitzvah at thirteen instead, so choose the age your community uses.
The calculator converts the birth date to the Hebrew calendar (after sunset counts as the next day), finds the same Hebrew date 13 or 12 years later, and applies the birthday rules for Adar in leap years and for 30 Cheshvan and 30 Kislev. The Torah portion is the weekly reading for the first Shabbat on or after that date. If that Shabbat falls on a festival, the festival reading replaces the weekly portion, and the calculator says so.
Israel and the Diaspora
Outside Israel, Pesach and Shavuot each have one more festival day. When that extra day falls on Shabbat, Israel reads the next weekly portion and the Diaspora reads the festival portion, so for a few weeks Israel is one portion ahead. This happens in some years, not all, so pick the schedule your synagogue follows.
Our Torah-reading schedule reproduces the standard sequence, including the years when two portions are read together (for example Vayakhel–Pekudei or Matot–Masei). It is tested against Hebcal for every Shabbat from 1800 to 2240, for both Israel and the Diaspora.
How the Hebrew calendar works
The Hebrew calendar is lunisolar. Months follow the moon (29 or 30 days), and a thirteenth month, Adar I, is added in 7 years of every 19 so that Pesach stays in spring. Two months, Cheshvan and Kislev, change length from year to year so that Rosh Hashana does not fall on certain weekdays. As a result a Hebrew year has between 353 and 385 days, and a Hebrew date moves around the Gregorian calendar by up to a month.
A Hebrew day runs from nightfall to nightfall. Someone born on a Tuesday evening after sunset was born, by the Hebrew calendar, on Wednesday’s date. Tick the after-sunset box in that case. If the time was close to sunset, check the local sunset time for that date, or ask your rabbi.
Our conversions use the fixed arithmetic of the Hebrew calendar as set out in Reingold and Dershowitz, Calendrical Calculations, and are tested against the open-source Hebcal library for every day from 1800 to 2239.