Many observances in Jewish law are performed at specific times during the day. The calculation of these halachic times, known as zmanim (Hebrew for “times”), depends on the various astronomical phenomena of the day for the specific locale. Sunrise, sunset, the amount of time between them, and the sun’s angular position before rising are all factors that determine the halachic times and “hours” of the day.

[The hour has special meaning in Jewish law. When we say that a certain mitzvah may be performed three hours into the day, this doesn’t mean at three in the morning, or three clock hours after sunrise. Rather, an hour in halachah means 1/12th of the day. Thus, if the sun rises at 5 AM and sets at 7:30 PM, one shaah zmanit, or proportional hour (pl. shaot zmaniot), will be 72.5 minutes, and all calculations will use that number.]

Below you will find the times, their meanings, and some of their associated mitzvot.

Alot Hashachar:

The time when some of the light of the sun begins to be noticeable on the eastern horizon.

Communal fasts (other than Yom Kippur and Tisha B’Av) begin at this time. According to Torah law, dawn marks the beginning of the day, and all mitzvahs associated with daytime hours—such as hearing the shofar, shaking the lulav, the recitation of the Shema, or the daytime hearing of the Megillah—can now be done. For various reasons, however, the Sages instituted that the observance of these mitzvahs should be delayed until hanetz hachamah, or, in some cases, until misheyakir.

Misheyakir - Earliest time for Tallit and Tefillin:

The time when there is enough light so that one can recognize a casual acquaintance from the distance of four cubits.

Ideally, this is the earliest time to to say Shema, put on tallit or tefillin, and make a blessing on tzitzit.

Hanetz Hachamah - Sunrise:

The moment when the top edge of the sun’s disk comes into view at sea level.

This is ideally the earliest time to say the morning Amidah. When there is a need to pray the Amidah earlier, a rabbinic authority should be consulted. It is also the earliest time for other daytime mitzvahs, such as shofar and lulav.

Latest Shema:

Three shaot zmaniot into the day. Latest time of the day to fulfill the biblical requirement to recite the morning Shema. Bedi’eved (if one missed this time), one should still recite Shema with its blessings until chatzot.

Latest Tefillah:

Four shaot zmaniot into the day—ideally the latest time for Shacharit, the morning prayer. However, if this time was missed, Shacharit may be recited until chatzot. (This is also the last time to eat chametz on Erev Pesach)

Chatzot - Midday:

The halfway point between sunrise and sunset, this is the latest time to say Shacharit. Half-day fasts end at this time.

Minchah Gedolah:

Half an hour after chatzot, this is the earliest time one may recite Minchah, the afternoon prayer.

Minchah Ketanah:

Two and a half proportional hours before the end of the day, this zman has certain ramifications with regard to beginning a meal (especially on Erev Shabbos and Yom Tov). According to some, this begins the ideal time for praying Minchah. In addition, some consider this zman to be relevant to some of the laws of Family Purity. Consult a rabbinic authority for details.

Plag Haminchah:

One and a quarter proportional hours before the end of the day, plag haminchah is the earliest time one may light Shabbat candles (and Chanukah candles on Erev Shabbat of Chanukah). When in need, one may pray Ma’ariv as early as plag haminchah (though the Shema must be repeated after tzeit). In addition, if one wishes to begin Shabbat early, one may begin it as early as plag haminchah. Consult your rabbinic authority for further details.

Candle-Lighting Time:

Candle lighting time for Erev Shabbat and Erev Yom Tov is 18 minutes before shekiah, sunset.

Note: Some communities start Shabbat early in the summer. In such communities, one cannot light candles 18 minutes before sunset. Everyone must follow the custom of the community and light before the community begins Shabbat. In addition, several communities (such as Jerusalem) use a year-round standard which is more than 18 minutes for candle lighting. In such communities, everyone must follow the local custom and light Shabbos candles at the time the rest of the community lights. Please contact your local rabbi for details.

Shekiah - Sunset:

The moment when the top edge of the sun’s disk disappears from view at sea level.

All mitzvahs associated with daytime should be completed by this time. It is also the appropriate time to finish Minchah. If one didn’t pray Minchah before shekiah, one may still do so afterwards.

Note: though the day is generally considered to end at sunset, with regard to scheduling a circumcision for a boy born a few minutes after sundown and with regard to certain details of the Laws of Family Purity, one should consult a rabbinic authority for further guidance.

Bein Hashmashot - Twilight

For some matters the time between sundown and nightfall is considered a safek yom safek laylah, a doubt whether it is still part of the daytime or the coming nighttime. Therefore all daytime mitzvahs must be completed before and nighttime mitzvahs should be fulfilled after it concludes, at tzeit.

If a baby boy is born during bein hashmashot, his circumcision will be on the 9th day (or later, if the 9th day is Shabbat or Yom Tov). For example, if he is born on bein hashmashot of Monday evening, it will take place on the following Tuesday morning.

Tzeit Hakochavim - Nightfall:

The point when 3 medium stars are observable in the night time sky with the naked eye.

This time is the beginning of night for all mitzvahs, including the Torah obligation of reading the evening Shema, counting the Omer, the end of fast days (except for Yom Kippur) and matters relating to the laws of Family Purity. It the preferred time to begin praying Maariv. A baby boy born after tzeit will have his circumcision exactly 8 days later, even if that day is Shabbat. Consult a rabbinic authority for details. The time to end Shabbat and Yom Tov is addressed below.

Shabbat and Yom Tov Ends

The time when Shabbat and Yom Tov ends is defined as the point at which at least one cluster of three small stars is observable in the night time sky with the naked eye.

No melachah (forbidden labor) should be done before this time. Ma’ariv and Havdalah should begin after this time.

Shaah Zmanit:

Proportional hour—i.e., an hour according to halachah. Total daylight hours divided by 12.