Jewish boys are circumcised on the eighth day of life, counting the day of birth as day one. This timing comes directly from a commandment in the Book of Genesis, where God instructs Abraham that every male among his descendants “that is eight days old shall be circumcised.” The ceremony is called a brit milah (often shortened to “bris”), and it is one of the most universally observed traditions in Judaism.
Why the Eighth Day
The eighth-day requirement appears twice in the Hebrew Bible. Genesis 17:10–14 frames circumcision as a physical sign of the covenant between God and the Jewish people, while Leviticus 12:3 restates the timing: “And in the eighth day the flesh of his foreskin shall be circumcised.” In Hebrew, the verb meaning “to seal a covenant” translates literally as “to cut,” and Jewish scholars understand the removal of the foreskin as symbolically sealing that agreement.
Unlike circumcision practices in many ancient cultures, which were tied to puberty or coming of age, the biblical commandment deliberately moved the ritual to infancy. This shifted its meaning away from a rite of passage and toward a sign of ethnic and religious belonging from birth.
How the Day Is Counted
The Jewish calendar day begins at sunset, not midnight. A baby born on a Monday before sunset has his brit milah the following Monday. But if the birth happens in the late afternoon on a Friday, in the uncertain window between sunset and full nightfall, it becomes unclear whether the baby was born on Friday or Shabbat (Saturday). In that case, the circumcision is pushed to Sunday to avoid any doubt.
The ceremony must take place during daylight hours. Performing it at night, or before the eighth day, is not considered valid under Jewish law. There is also a tradition to schedule it as early in the day as possible, so many brit milah ceremonies happen in the morning.
Shabbat and Jewish Holidays
When the eighth day falls on Shabbat or a major Jewish holiday, the circumcision still goes forward on time. This is one of the few rituals that overrides the usual restrictions on those days. However, all preparations, including setting up instruments and preparing the celebratory meal, must be completed before Shabbat begins at sunset on Friday. The ceremony is typically held at home rather than at a synagogue, since carrying objects outside is not permitted on Shabbat.
The same rule applies to holidays like Rosh Hashanah, Passover, Sukkot, and Shavuot. On Yom Kippur, the circumcision takes place during morning services after the Torah reading, and the celebratory meal is held after the fast ends that night. On fast days like Tisha B’Av, the meal is similarly postponed until evening.
There is one important exception: if the circumcision has already been postponed for any reason, such as a medical delay, it can no longer be performed on Shabbat or a holiday. It moves to the next available weekday. The same applies to babies born by cesarean section, whose brit milah does not override Shabbat even if day eight falls on Saturday. In that case, the ceremony takes place on Sunday.
When the Ceremony Is Delayed
Jewish law requires that the baby be healthy enough for the procedure, and medical concerns take priority over the eighth-day deadline. Jaundice is the most common reason for postponement. Mohels (the trained ritual circumcisers who perform the brit milah) typically will not proceed when a newborn’s bilirubin level, the measure of the substance that causes the yellowing, is above 10. Once jaundice resolves and levels drop to a safe range, the ceremony can go ahead.
The rules for rescheduling depend on how serious the illness was. If the baby had a condition affecting the whole body, such as a fever or systemic infection, Jewish law requires waiting a full seven days after complete recovery before performing the circumcision. If the issue was localized to one part of the body, there is no waiting period, and the brit milah can happen as soon as the baby is cleared.
In cases of severe jaundice, the seven-day waiting period after recovery also applies. For families of babies with hemophilia or a family history of brothers who suffered dangerous bleeding from circumcision, the procedure may be indefinitely postponed to protect the child’s life. Jewish law treats the preservation of life as a value that supersedes nearly all other commandments.
Who Performs the Ceremony
The brit milah is performed by a mohel, a person trained in both the surgical technique and the religious requirements of the ritual. This is distinct from a hospital circumcision done by a doctor in the first day or two after birth, which is a medical procedure without the religious components. A hospital circumcision does not fulfill the commandment of brit milah.
During the ceremony, the baby is held on the lap of a person designated as the sandek, a role considered a great honor, similar to a godparent. After the circumcision, blessings are recited, the baby is formally given his Hebrew name, and a celebratory meal called a seudat mitzvah follows. The entire ritual typically lasts only a few minutes, though the gathering around it can go much longer.
Adult and Late Circumcision
The eighth-day timing applies specifically to infant boys born into Jewish families. For male converts to Judaism, or for Jewish boys whose circumcision was postponed indefinitely due to medical reasons, the procedure can be performed later in life. In these cases, the circumcision is still considered a brit milah when done with the proper religious intent and by a qualified mohel, regardless of the person’s age.