ZmanimBar · Calculation methods
Every formula behind the 28 times.
ZmanimBar computes each halachic time on the device from the observer's own coordinates. This page is the full specification it is built from — the anchors, the temporal hours, the solar-depression angles, and which times appear on which days.
This is the same document the app is written against: when the page and the app disagree, that is a bug in the app.
Notation
The anchors every formula is measured from
Two solar days underpin everything. The GRA's is bounded by astronomical sunrise and sunset; the Magen Avraham's by dawn and dusk at 16.1° — symmetric in degrees rather than a fixed 72 minutes. Every temporal hour below is one twelfth of one of them.
| Symbol | Meaning |
|---|---|
| netz° | Astronomical sunrise — the sun crosses the horizon (0°) on a flat plane, independent of elevation. |
| shkia° | Astronomical sunset — the sun crosses the horizon (0°). |
| netz↑ / shkia↑ | Sunrise and sunset as seen from the observer's elevation (horizon dip). |
| GRA hour | (shkia° − netz°) ÷ 12. Always astronomical, never the visible times. |
| alos 16.1° | The sun 16.1° below the horizon before sunrise — dawn, the “72 minutes in degrees”. |
| tzeis 16.1° | The sun 16.1° below the horizon after sunset. |
| MGA hour | (tzeis 16.1° − alos 16.1°) ÷ 12. Symmetric in degrees. |
- Temporal hours are never measured from the visible sunrise or sunset. The GRA's hour runs between the sea-level times, the Magen Avraham's between the two 16.1° moments.
- Elevation applies only at the horizon. It shifts the visible sunrise and sunset; the sea-level times and every angle-based time are unaffected. There is no setting to get wrong.
The list
28 times, and when each one appears
17 of the 28 are shown every day. The other 11 belong to a particular day — the chametz times to erev Pesach, musaf to Shabbat and Rosh Chodesh, and so on — and the app shows them only then, so an ordinary weekday list stays short.
Before sunrise, and sunrise itself
| # | Time | What it is | Formula | When it appears |
|---|---|---|---|---|
| 1 | Alos HaShachar — stringent | Early dawn, the 90-minute measure expressed in degrees | sun 19.8° below the horizon | Every day |
| 2 | Alos HaShachar — primary | Dawn, the 72-minute measure in degrees; the start of the MGA day | sun 16.1° below the horizon | Every day |
| 3 | Misheyakir — tzitzit & tefillin | “When you can recognise your friend” — about an hour before sunrise | sun 11.5° below the horizon | Every day |
| 4 | Sunrise — sea level (mishor) | Astronomical sunrise on a flat plane | netz° (0°, sea level) | Every day |
| 5 | Sunrise — visible (nireh) | Sunrise as seen from your elevation, therefore earlier | netz↑ (0° + horizon dip) | Every day |
The end of the morning times
| # | Time | What it is | Formula | When it appears |
|---|---|---|---|---|
| 6 | Sof zman kriat shema — MGA | End of the third hour from dawn (72) | alos 16.1° + 3 × MGA hour | Every day |
| 7 | Sof zman kriat shema — GRA | End of the third hour from sunrise | netz° + 3 × GRA hour | Every day |
| 8 | Sof zman tefila — MGA | End of the fourth hour | alos 16.1° + 4 × MGA hour | Every day |
| 9 | Sof zman tefila — GRA | End of the fourth hour | netz° + 4 × GRA hour | Every day |
| 10 | End of eating chametz — MGA | End of the fourth hour — the same moment as sof zman tefila | alos 16.1° + 4 × MGA hour | Erev Pesach |
| 11 | End of eating chametz — GRA | End of the fourth hour | netz° + 4 × GRA hour | Erev Pesach |
| 12 | End of biur chametz — MGA | End of the fifth hour | alos 16.1° + 5 × MGA hour | Erev Pesach |
| 13 | End of biur chametz — GRA | End of the fifth hour | netz° + 5 × GRA hour | Erev Pesach |
Midday and the afternoon
| # | Time | What it is | Formula | When it appears |
|---|---|---|---|---|
| 14 | Chatzos — midday and midnight | The sun at the middle of its arc | midpoint of netz° and shkia° | Every day |
| 15 | Mincha Gedola | Half an hour after midday | netz° + 6.5 × GRA hour | Every day |
| 16 | Sof zman musaf | End of the seventh hour | netz° + 7 × GRA hour | Shabbat · Yom Tov · Rosh Chodesh · Chol HaMoed |
| 17 | End of a bread meal (erev Shabbat) | End of the ninth hour — so as not to spoil the Shabbat meal | netz° + 9 × GRA hour | Erev Shabbat / Yom Tov |
| 18 | Mincha Ketana | Nine and a half hours | netz° + 9.5 × GRA hour | Every day |
| 19 | Plag HaMincha | Ten and three quarter hours | netz° + 10.75 × GRA hour | Every day |
Sunset, nightfall and candle lighting
| # | Time | What it is | Formula | When it appears |
|---|---|---|---|---|
| 20 | Sunset — sea level (mishor) | Astronomical sunset on a flat plane | shkia° (0°, sea level) | Every day |
| 21 | Sunset — visible (nireh) | Sunset as seen from your elevation, therefore later | shkia↑ | Every day |
| 22 | Tzeis HaKochavim — Maariv | Nightfall for a weekday Maariv (three quarters of a mil) | sun 4.61° after sunset | Every day |
| 22+ | End of the fast | The stringent moment for ending a fast | sun 6.45° after sunset | The four minor fasts |
| 23 | Tzeis HaKochavim — Shabbat | The stringent nightfall, the practice in Eretz Yisrael | sun 8.5° after sunset | Shabbat / Yom Tov and its eve |
| 24 | Tzeis HaKochavim — Chazon Ish | The Chazon Ish's measure | sun 9.28° after sunset | Every day |
| 25 | Tzeis Rabbeinu Tam — fixed minutes | 72 clock minutes after the visible sunset | shkia↑ + 72 fixed minutes | Shabbat / Yom Tov |
| 26 | Tzeis Rabbeinu Tam — degrees | 72 minutes expressed in degrees after astronomical sunset | sun 16.1° after sunset | Shabbat / Yom Tov |
| 27 | Candle lighting | Before sunset, by the custom of the city | shkia° − (40 / 30 / 22 min) | Erev Shabbat / Yom Tov |
Candle lighting — minutes by city
| Minutes | Cities |
|---|---|
| 40 | Jerusalem, Beitar Illit |
| 22 | Gush Dan (Tel Aviv, Bnei Brak, Ramat Gan, Holon, Bat Yam, Petach Tikva) and Ashdod |
| 30 | Everywhere else in Israel — the default |
| 18 | Outside Israel |
Decisions
Three choices that are not the library's defaults
- The GRA's hours are always astronomical. They are measured between sea-level sunrise and sea-level sunset, never between the visible ones — so your elevation changes the sunrise you see, but not the hour that divides the day.
- The Magen Avraham's hours are symmetric 16.1°. Dawn and dusk are taken at the same depression angle rather than a fixed 72 minutes, which keeps the measure honest away from Israel and across the seasons.
- Nightfall is stated by explicit angle. 4.61°, 6.45°, 8.5°, 9.28° and 16.1° are each shown for what they are, instead of collapsing them into one default. An angle means the same thing at every latitude; a fixed number of minutes does not.
These times are computed, and they vary with place, elevation and season. For practical halacha follow a reliable printed luach and your own posek.
Contact
Corrections are welcome
If a formula here is wrong, or a time should appear on a day it does not, write — it reaches the developer directly.
support@bdtech.app