Nishmat's Women’s Health and HalachaIn memory of Chaya Mirel bat R' Avraham

  • Hebrew
  • English
  • Espnaol
  • Francais
  • donate

Duration of moch

22 March, 2012


What is the definition of nightfall for the moch? Is it the time Shabbat goes out (i.e., 36 minutes after shkia), or 72 minutes?


There are many opinions about how tzeit hakochavim (nightfall) is calculated – 18 minutes after sunset, 24 minutes, 36 minutes, 42 minutes, 72 minutes… 

In Israel, most opinions hold that the moch dachuk should be in place for approximately 18 minutes after sunset. Outside of Israel, according to many opinions, this period is closer to 35/40 minutes.

You need not keep the moch in for 72 minutes after sunset. If the moch is uncomfortable, you may remove it after 18 minutes.

Rulings on this question vary based both on custom and on latitude (the closer you are to the equator, the shorter the interval between sunset and nightfall). Therefore, it is a good idea to ask a local rabbi, yoetzet, or kallah teacher about the accepted practice in your community.

For assistance with calculating halachic times for any location, see Time of Sunrise/Sunset.

This internet service does not preclude, override or replace the psak of any rabbinical authority. It is the responsibility of the questioner to inform us of any previous consultation or ruling. As even slight variation in circumstances may have Halachic consequences, views expressed concerning one case may not be applied to other, seemingly similar cases. All health and health-related information contained within Nishmat's Women's Health & Halacha Web site is intended to be general in nature and should not be used as a substitute for consulting with your health care professional. The advice is intended to offer a basis for individuals to discuss their medical condition with their health care provider but not individual advice. Although every effort is made to ensure that the material within Nishmat's Women's Health & Halacha Web site is accurate and timely, it is provided for the convenience of the Web site user but should not be considered official. Advice for actual medical practice should be obtained from a licensed health care professional.

For further questions or comments: 

The Nishmat Women's Health and Halacha Site is a public service of Nishmat, The Jeanie Schottenstein Center for Advanced Torah Study for Women. This project and others like it are made possible by contributions from people like you. If you have benefited from the service, and wish to enable us to help others, click here to donate.

Users of Internet filtering services: This site discusses sensitive subjects that some services filter without visual indication. A page that appears 100% complete might actually be missing critical Jewish-law or medical information. To ensure that you view the pages accurately, ask the filtering service to whitelist all pages under

Accessibility Toolbar