"Its redemption [shall be performed] from the age of a month"—Numbers 18:16.

This means that the pidyon haben (firstborn redemption ceremony) should be held on the 31st day after the boy's birth. (Both the day of birth and the day of the pidyon haben are included in the 31 days.) Although the obligation to perform the ceremony technically begins at nightfall following day 30 (since the Jewish day begins at nightfall), the custom of Ashkenazic Jews is to hold the pidyon haben in the afternoon of the 31st day,1 and the custom of Sephardic Jews is to schedule the pidyon haben for the first possible opportunity, which is the night preceding the 31st day.

When Is Day 31?

In order to find out when the date of the pidyon haben should be, first find out the baby’s Jewish date of birth. You can find the date via this Jewish Birthday Calculator. Since the Jewish day starts at nightfall, the time of birth may also be significant (the Birthday Calculator will help you with this as well).

The date of the pidyon haben always falls four weeks and two days after the day of birth. It would not necessarily be on the same day of the next month, since Jewish months do not all contain the same number of days. So, for example, if the baby was born on Friday, the 10th of the Jewish month of Shevat, February 3rd, the 31st day would be Sunday, the 10th of the Jewish month of Adar, March 4th (since Shevat always has 30 days). If, however, the baby was born on Thursday, the 10th of Tevet, January 5th, then the 31st day would be on Shabbat, the 11th of Shevat, February 4th (since Tevet only has 29 days).

If you find this confusing, ask a rabbi to assist you in finding the exact date.

When Day 31 Falls on a Special Day

  • If day 31 is on Shabbat or a major Jewish holiday (other than Chanukah, Purim or Chol Hamoed), the pidyon haben takes place on the next weekday.
  • If day 31 is on a Friday, the meal should be scheduled for early in the afternoon, and only a quorum of 10 men (in addition to the father, the kohen and close relatives) should participate, so that the meal does not detract from the Shabbat festivities later that evening.
  • If day 31 is a public fast day, the pidyon haben is held right before nightfall, and the festive meal is celebrated that evening. (The wine that the kohen usually drinks during the ceremony is drunk by a minor who is not yet obligated to fast.)
  • If day 31 falls on the day before Passover, the pidyon haben should be held in the morning, early enough so that bread may be eaten during the festive meal.2

If Day 31 Passed

If, for whatever reason, the 31st day has passed and the pidyon haben did not take place, the baby's father should do it at the earliest possible opportunity.

If the firstborn reaches the age of 13 (Bar Mitzvah) without having had a pidyon haben, he is obligated to redeem himself. Click here for more on this topic.