I know that a girl has her bat mitzvah on her 12th Hebrew birthday, and a boy has his bar mitzvah when he turns 13. Why are these two ages designated for this milestone, and why do boys lag behind by a year?


The ages of 12 and 13 are around the time when most young adults typically begin to physically mature and reach puberty.1 Additionally, when a boy turns 13 and a girl turns 12, they are considered to have reached the “age of maturity,” a time when they have developed enough understanding to be responsible for their actions. Therefore, they are called a bar/bat mitzvah, which literally means a “son/daughter of the commandment,” or a “man/woman obligated to do mitzvahs,” since they are now responsible for keeping the Torah and its mitzvahs.

The Torah Sources

Some explain that, like most other halachic measurements, the fact that the age of maturity is 12 or 13 is simply an oral tradition that G‑d imparted to Moses on Mount Sinai (commonly called Halachah L’Moshe MiSinai).2

Others explain that this is derived from the Torah’s account of the destruction of the city of Shechem by Simeon and Levi in retaliation for the rape of their sister Dinah. The verse “On the third day . . . Jacob’s two sons, Simeon and Levi, Dinah’s brothers, each man took his sword and confidently attacked the city . . .”3 The term “man” (ish) is used to refer to both brothers, the younger of whom, Levi, was exactly 13 years old at the time.4 This is the youngest age at which someone is referred to as a “man” in the Torah; thus, we derive that the Torah considers a male of 13 years to be a man.5 6

The Feminine Advantage

Just as a boy is considered to be a man at the same time that he generally begins to experience physical maturity, a girl generally matures more quickly, and is therefore considered to be a woman earlier as well—i.e., when she turns 12 years old.7

According to some explanations in the Talmud, this feminine advantage can be inferred from the Torah’s description of the creation of the first woman, Eve: “The L‑rd G‑d built the side that He had taken from man into a woman, and He brought her to man.”8 The word translated as “built,” vayiven, can also mean “and He gave her understanding,” implying that G‑d created a woman in such a way that she reaches mental maturity earlier than a man.9

Food for Thought

A bar mitzvah is not a graduation, when we celebrate an accomplishment of the past. On the contrary, it is a beginning. It is the start of an adult life, in which one more Jewish person will serve G‑d using his or her newfound wisdom to make the world a better, more G‑dly place.

Mazal tov!