How zmanim are calculated
This page spells out exactly how each zman shown on the calendar is worked out, so you know what you are looking at.
Which place the times are for
Every zman is calculated for the city you pick in the zmanim box: type an address, drop a pin on the map, choose one of the popular cities, or press “use my location”.
Your choice is kept in your browser, so the calendar and the zmanim box always show the same city. Until you pick a place, the times shown are for Kiryas Joel.
The time zone and daylight saving are taken from the coordinates of that place, so the times are already in the local clock time of the city you picked.
The zmanim and how each one is worked out
| Zman | How it is worked out | Note |
|---|---|---|
| Alos Hashachar | 72 minutes before sunrise | 72 ordinary clock minutes, not shaos zmanios. |
| Talis and tefillin (misheyakir) | 22 minutes after alos — 50 minutes before sunrise | Also a fixed number of clock minutes. |
| Hanetz hachamah (sunrise) | Astronomical sunrise for your coordinates | The moment the top edge of the sun is seen at a flat horizon (zenith 90.833°, which allows for refraction and the radius of the sun). Mountains and elevation are not taken into account. |
| Latest krias shema | Alos plus a quarter of the day from alos until tzeis hakochavim | The Magen Avraham reckoning: the day runs from alos (72 minutes before sunrise) until tzeis (72 minutes after shkia), so the hours are longer than a Gra hour. |
| Latest krias shema (Gra) | Sunrise plus three zmanis hours of the sunrise-to-shkiah day | The Gra reckons the day from sunrise until shkiah, so this falls later than the Magen Avraham time. |
| Latest tefillah | Alos plus four zmanis hours — a third of the day from alos until tzeis hakochavim | Also the Magen Avraham reckoning, with the same long hours as krias shema. |
| Latest tefillah (Gra) | Sunrise plus four zmanis hours of the sunrise-to-shkiah day | The Gra reckoning, in the shorter sunrise-to-shkiah hours. |
| Chatzos hayom (midday) | Exactly halfway between sunrise and sunset | The two shitos agree here: alos is 72 minutes before sunrise and tzeis 72 minutes after shkiah, so the midpoint is the same either way. |
| Mincha gedola | Alos plus six and a half zmanis hours — half a zmanis hour after chatzos | The Magen Avraham reckoning, in alos-to-tzeis hours. |
| Mincha gedola (Gra) | Sunrise plus six and a half zmanis hours of the sunrise-to-shkiah day | The Gra reckoning — also half a zmanis hour after chatzos, but in shorter hours. |
| Mincha ketana | Alos plus nine and a half zmanis hours | The Magen Avraham reckoning, in alos-to-tzeis hours. |
| Mincha ketana (Gra) | Sunrise plus nine and a half zmanis hours of the sunrise-to-shkiah day | The Gra reckoning; this falls earlier than the Magen Avraham time. |
| Plag hamincha | Alos plus ten and three quarter zmanis hours | The Magen Avraham reckoning — a zmanis hour and a quarter before tzeis hakochavim. |
| Plag hamincha (Gra) | Sunrise plus ten and three quarter zmanis hours of the sunrise-to-shkiah day | The Gra reckoning — a zmanis hour and a quarter before shkiah. |
| Shkiah (sunset) | Astronomical sunset for your coordinates | The same zenith as sunrise, at a flat sea-level horizon. |
| Tzeis hakochavim (nightfall) | 72 minutes after shkiah | 72 fixed clock minutes (Rabbeinu Tam), not a degrees-based tzeis. |
Magen Avraham and the Gra
Every zman measured in zmanis hours has two reckonings: the Magen Avraham measures the day from alos until tzeis hakochavim, the Gra from sunrise until shkiah. The Magen Avraham hours are the longer ones, so its morning zmanim fall earlier and its afternoon zmanim later.
In the zmanim list an unmarked zman is always the Magen Avraham. The Gra time is shown under it in smaller type, and appears once you switch on “Full zmanim” in the zmanim box options.
Candle lighting and the end of Shabbos
On the calendar, Friday shows a candle icon with the time 15 minutes before shkiah, and Shabbos shows a sparkle icon with tzeis hakochavim — 72 minutes after shkiah. Hover over the icon to see which zman it is.
Worth knowing
- Wherever it says 72 or 22 minutes, those are ordinary clock minutes, not shaos zmanios.
- The calculation is at sea level with a flat horizon; the elevation of the place is not taken into account.
- In the zmanim box you can switch between a 12- and 24-hour clock and choose whether to show seconds.
- Minhagim and shitos differ on these times. For a halachah lemaaseh follow your rov or your shul’s luach.