Why candle lighting is 18 minutes before sunset, and how this site calculates
In almost every calendar you will find candle lighting set at 18 minutes before sunset. Why 18? And why 40 in Jerusalem? Here is what stands behind the numbers, and how this site calculates them.
Adding to Shabbat
The basic idea is called "tosefet Shabbat." Our Sages learned from the Torah that there is a mitzvah to add from the weekday to the holy time, meaning we accept Shabbat a little before it arrives. The Talmud discusses this in tractates Rosh Hashanah and Yoma. That is why candle lighting comes before sunset: so that Shabbat begins without anyone desecrating it by mistake.
How much time should be added? Halacha did not fix one number that everyone accepts. Each place adopted an amount that seemed reasonable to it: short enough not to be a burden, long enough to feel the difference between the passing day and the arriving Shabbat.
Where 18 comes from
Eighteen minutes is the most widespread custom in the world. Some connect it to the time it takes to walk a mil, according to certain opinions, and there are other explanations. We do not need to decide between them, because in practice it is a custom that took root in many communities and became the default of calendars, so we use it as our default too.
It is important to understand that the number is a community custom and not a uniform obligation. Someone who lights earlier simply adds to the published time. Do not light later than the published time without asking.
Local customs
In several places the custom is different, and it is worth knowing them:
- Jerusalem: 40 minutes before sunset, an old custom of the city.
- Haifa: 30 minutes, as published in the city calendars.
- Petah Tikva: 22 minutes.
- Modiin: 20 minutes, according to local publications.
- United States: most communities use 18 minutes, and some use 15 or 20.
These numbers are accepted customs, and exactly how far each applies varies between neighborhoods and congregations. If your rabbi published a calendar, it decides.
What this site uses
This site calculates as follows:
- Candle lighting: 18 minutes before sunset by default. In Jerusalem and its immediate surroundings, within 12 kilometers of the city center, the default is 40 minutes.
- You can change the number of minutes in the app to match your community. Your choice is saved on your device.
- End of Shabbat: when the sun is 8.5 degrees below the horizon.
- Rabbeinu Tam: 72 minutes after sunset, shown beside the end of Shabbat for those who follow that opinion.
The calculation itself is done with the hebcal calculation engine, and we compare the results against hebcal.com for many cities across a full year. Sunset is calculated for the coordinates of the place you choose, so it may differ by a minute or two from a calendar based on another large city.
What sunset is
Sunset is the moment the sun disappears below the horizon line, taking into account the bending of light in the atmosphere. It is not the moment of darkness. After sunset there is still light in the sky, called twilight. Halacha distinguishes between several stages: sunset, bein hashmashos and nightfall, and each has a different significance. The guide on when Shabbat ends goes into this.
Why the times change every week
Sunset moves by a few minutes every week. In summer the sun sets late and in winter early. In Israel candle lighting in winter is around 4:30 PM, and in summer close to 7:30 PM. In New York it is around 4:15 PM in winter and after 8:00 PM in summer. Anyone planning Shabbat by the season finds that the day can be very long or very short, which is another good reason to check the calendar each week.
A closing note
All the numbers here are customs and opinions, and not all are binding. When there is a difference between what the site shows and what your community rabbi publishes, follow your rabbi. You can easily match the site to your custom by choosing the number of minutes, and see the right time for you in the live times.
More guides
- How Shabbat candle lighting works: a complete guide
- When Shabbat ends: nightfall, 8.5 degrees and Rabbeinu Tam
- Candle lighting times by location: why exact beats a city list