Here's a great tip:
Enter your email address and we'll send you our weekly magazine by email with fresh, exciting and thoughtful content that will enrich your inbox and your life, week after week. And it's free.
Oh, and don't forget to like our facebook page too!
Contact Us

About Our Zmanim Calculations

About Our Zmanim Calculations

 Email

Important note: Please do not rely on these times until the last minute. One should always add (or subtract, as needed) at least two minutes to each published zman.

Why this is important: Even with the best mathematical calculations, halachic times have built-in inaccuracies. These include: variances relating to temperature, barometric pressure and other factors; variances between clocks (even on smartphones); slight differences of time within a single city or even zip code; rounding; variations in halachic interpretations; and other factors.

Alos Hashachar—Dawn

Alos is defined as 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 preferably be delayed until hanetz, or in some cases until misheyakir.

The time is calculated as the point at which the center of the sun’s disk is 16.9 degrees below the horizon, which is its position 72 minutes before hanetz amiti in Jerusalem at the equinox.

Note: in places where the sun does not go below 16.9 degrees during part of the summer, alos is reached as soon as the sun passes its lowest point of the night and begins heading upward again—i.e., at chatzos halailah, midnight. For further guidance, please consult your rabbinic authority.

Misheyakir—Earliest time for Tallis and Tefillin

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

This is the earliest time to to say Shema, put on tallis or tefillin, and make a berachah on tzitzis.

This time is calculated as the point at which the center of the sun’s disk is 10.2 degrees below the horizon, which is its position 45 minutes before sunrise in Jerusalem at the equinox.

Hanetz—Sunrise

Sunrise is defined as 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.

The time is calculated as the point at which the center of the sun’s disk is 0.833 degrees below the horizon. This calculation is based on average atmospheric conditions.

Hanetz Amiti—True Sunrise

According to the Alter Rebbe, hanetz amiti, true (halachic) sunrise, is when the top of the sun’s disk is visible at an elevation similar to the mountains of Eretz Yisrael.

The time is calculated as the point at which the center of the sun’s disk is 1.583 degrees below the horizon.

Note: Hanetz amiti is used only for calculating certain zmanim, and is intentionally unpublished. For practical purposes, daytime mitzvahs like shofar and lulav should not be done until after the published time for hanetz—sunrise.

Sof Zman Kerias Shema—The Latest Time for Morning Shema

Sof zman kerias Shema is defined as the end of the first quarter of the halachic day, or when 3 proportional hours, shaos zmaniyos, have passed.

It is the latest time to recite the morning Shema.

The time is calculated by adding three shaos zmaniyos to hanetz amiti.

Sof Zman Tefillah—The Latest Time to Say the Morning Amidah

Sof zman tefillah is defined as the end of the first third of the halachic day, or when 4 proportional hours, shaos zmaniyos, have passed.

Ideally, one should complete the Amidah of Shacharis by this time. If this time has been missed, one may still recite it until chatzos hayom. It is also the last time to eat chametz on Erev Pesach.

The time is calculated by adding four shaos zmaniyos to hanetz amiti.

Sof Zman Biur Chametz—Last Time to Burn Chametz (on Erev Pesach)

Sof zman biur chametz is defined as the time when five proportional hours, shaos zmaniyos, have passed since the beginning of the halachic day.

This zman is relevant only on Erev Pesach. By this time, one must complete the burning of chametz; all chametz that was sold must have been put away; and one may no longer have any benefit from chametz.

The time is calculated by adding 5 shaos zmaniyos to hanetz amiti.

Chatzos Hayom—Halachic Noon

Chatzos, halachic noon, is defined as the midpoint of the day.

This is the latest time one is permitted to recite the Amidah of Shacharis.

The time is calculated as the halfway point between hanetz amiti and shkiah amitis.

Minchah Gedolah—The Earliest Time to Pray Minchah

Minchah gedolah is defined as half an hour after chatzos hayom.

This is the earliest time one can begin praying Minchah.

The time is calculated by adding 6.5 shaos zmaniyos to hanetz amiti.

Note: During fall and winter, when this time is less than 30 minutes after chatzos hayom, it is preferable to wait a full 30 minutes after chatzos hayom to pray Minchah.

Minchah Ketanah

Minchah ketanah is defined as two and a half shaos zmaniyos, proportional hours, before the end of the day.

This zman has certain ramifications with regard to beginning a meal (especially on Erev Shabbat and Yom Tov). According to some authorities, this begins the ideal time for praying Minchah. In addition, some authorities consider this zman to be relevant to some of the laws of family purity. Consult a rabbinic authority for details.

The time is calculated by subtracting 2.5 shaos zmaniyos from shkiah amitis.

Plag Haminchah

Plag haminchah is defined as one and a quarter shaos zmaniyos, 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 Maariv as early as plag haminchah (though the Shema must be repeated after tzeis). 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.

The time is calculated by subtracting 1.25 shaos zmanios from shkiah amitis.

Candle-Lighting (for Erev Shabbat and Yom Tov only)

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

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

Shkiah—Sunset

Shkiah is defined as 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 shkiah, one may still do so afterwards.

The time is calculated as the point at which the center of the sun’s disk is 0.833 degrees below the horizon. This calculation is based on average atmospheric conditions.

Note: though the day is generally considered to end at sunset, with regard to scheduling a bris 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.

Shkiah Amitis—True Sunset

According to the Alter Rebbe, shkiah amitis, true (halachic) sunset, is when the top of the sun’s disk disappears from view at an elevation similar to the mountains of Eretz Yisrael.

This time is calculated as the point at which the center of the sun’s disk is 1.583 degrees below the horizon.

Note: Shkiah amitis is used only for calculating certain zmanim, and is intentionally unpublished. For practical purposes, all daytime mitzvahs should be completed before the published time for shkiah—sunset.

Bein Hashemashos—Twilight

Bein hashemashos is the time between sundown and nightfall.

For some matters it is considered a safek yom safek lailah, a doubt whether it is still part of the daytime or the coming nighttime. Therefore all daytime mitzvahs must be completed before bein hashemashos, and nighttime mitzvahs should be fulfilled after bein hashemashos concludes, at tzeis.

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

This time is calculated from the beginning of shkiah amitis until tzeis.

Tzeis—Nightfall

Nightfall is defined as 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 obligations of reading the evening Shema and counting the Omer, the end of fast days (except for Yom Kippur), and matters relating to the laws of family purity. It is the preferred time to begin praying Maariv. A baby boy born after tzeis will have his bris 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.

Tzeis is calculated as the time at which the center of the sun’s disk is 6 degrees below the horizon, which is its position approximately 20 minutes after shkiah amitis in Jerusalem at the equinox.

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 nighttime sky with the naked eye.

No melachah (forbidden labor) should be done before this time. Maariv and havdalah should begin after this time.

It is calculated as the time when the center of the sun’s disk reaches 8.5 degrees below the horizon, which is its position 36 minutes after sunset in Jerusalem at the equinox.

Note: For countries located at very high latitudes, where bein hashmashos is very long, a rabbinic authority should be consulted with regard to the time to end Shabbat and Yom Tov.

Chatzos Halailah—Halachic Midnight

Chatzos, halachic midnight, is defined as the midpoint of the night.

Ideally one should try to do all nighttime mitzvahs, such as the nightly Shema, Maariv, and the counting of the Omer by this time. If one hasn’t done a nighttime mitzvah by chatzos, the mitzvah can still be fulfilled until alos. In addition, the eating of at least the first matzah of the Seder must be completed by this time. It is customary to try to finish the afikoman of the first Seder by chatzos halailah. Consult your rabbinic authority for details.

The time is calculated as the halfway point between shkiah amitis and hanetz amiti.

Shaah Zmanis (pl. Shaos Zmaniyos)—Proportional Hour(s)

A shaah zmanis is defined as 1/12 of the halachic day.

It is calculated by dividing the total amount of time between hanetz amiti and shkiah amitis into 12 parts. Each of these parts is considered a halachic hour, shaah zmanis.

© Copyright, all rights reserved. If you enjoyed this article, we encourage you to distribute it further, provided that you comply with Chabad.org's copyright policy.
 Email
Start a Discussion
1000 characters remaining
More in this section
Related Topics