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How accurate are candle lighting times?

Candle-lighting and Havdalah times are derived from sunset times, which are approximated from a location (latitude, longitude) and day of year. As of August 2020, Hebcal.com uses a sunset algorithm published by the US National Oceanic and Atmospheric Administration. The NOAA claims accuracy within 2 minutes except at extreme northern or southern latitudes.

Differences of 1-2 minutes between Hebcal and other sources publishing candle lighting times or sunset times are expected. Remember that candle lighting times can only be approximated based on location. Here are a few common reasons why you may see differences in candle lighting times:

  1. Different minhag on when to light candles. Hebcal defaults to 18 minutes before sundown for most locations (40 minutes before sundown for Jerusalem). Other sources may use 20 minutes before sundown. Hebcal gives an option to specify a different number of minutes before sunset if you don’t follow the 18-minute minhag.
  2. Slightly different sunset calculators. The sunset calculator we use on Hebcal.com as of August 2020 uses an algorithm published by the US National Oceanic and Atmospheric Administration. Hebcal’s NOAA algorithm is implemented in JavaScript using double-precision floating point arithmetic. Other sources may use a slightly different algorithm, for example one by Jean Meeus. However, even if the other source also uses the NOAA algorithm, the implementation could differ slightly; there are many constants and opportunities to round and truncate which could result in slight differences in the final calculated sunset time for a given day and location.
  3. Slightly different latitude/longitude definitions for a given city. Since 2013, Hebcal.com has been using lat/long definitions from GeoNames.org, which is available under a Creative Commons license. For the USA, we purchase a commercial ZIP code database from zip-codes.com. For very large cities, the sunset at the east side of the city might be a minute earlier than the west side of the city.
  4. Deliberate rounding down (or up). Hebcal rounds candle lighting (Friday) times down to the nearest minute, and rounds Havdalah times up to the nearest minute. To be more precise, we use the floor minute for candle-lighting, and we use the standard mathematical rounding rule for Havdalah. The idea here is that it’s better to display candle-lighting time as much as 59 seconds earlier than strictly necessary, and for Havdalah it’s better to wait an additional 30 seconds to end Shabbat/yontiff.
    • For example, if the exact candle lighting time from the sunset engine (including seconds) was at 20:02:31 or even 20:02:59, Hebcal displays candle-lighting as 20:02.
    • On the other hand, if the Havdalah calculation is 21:17:29, Hebcal will display 21:17. If it were 21:17:30 through 21:17:59, Hebcal displays 21:18.

As of August 2020, options for Havdalah times have also changed. Hebcal now offers an option to use tzeit hakochavim, the point when 3 small stars are observable in the night sky with the naked eye (sun 8.5° below the horizon). This option is an excellent default for most places on the planet. We also offer the option to use a fixed number of minutes past sundown. Typically one would enter 42 min for three medium-sized stars, 50 min for three small stars, 72 min for Rabbeinu Tam, or 0 to suppress Havdalah times.

Lastly, remember that the NOAA algorithm can only approximate the candle-lighting times for your location. If you ever have any doubts about Hebcal’s times, consult your local halachic authority.

Chanukah candle lighting times

Due to popular demand, we’ve added support for Chanukah candle-lighting times.

If you specify a city for Shabbat and Yom Tov candle lighting times, you’ll see Chanukah candle lighting show up as a timed event. If you don’t enable candle-lighting times (and instead choose the generic Diaspora or Israel locations) you’ll see Chanukah events show up as all-day (untimed) events reminding you to light candles that evening.

Candle-lighting times should show up on all iCalendar feeds (Google Calendar, Microsoft Outlook, iPhone, etc) when the application refreshes Hebcal events. This could take up to a week for the refresh, depending on the app.

Screen Shot 2015-12-01 at 11.17.10 PM

How can I look up candle-lighting times for any city in the world?

Hebcal offers a way to specify candle-lighting times location by latitude and longitude for remote or less-populated areas.

Hebcal supports already over 45,000 world cities. Just search for the name of any world city with population 5,000+. However, if you can’t find what you’re looking for in our location database, here’s how you could find candle-lighting times for a specific location.

Example: Ixiamas, Bolivia.

  1. Go to the Getty Thesaurus of Geographic Names at http://www.getty.edu/research/tools/vocabulary/tgn/
  2. Type “Ixiamas” in the Find box and click “Search” button
  3. Click on the link that says “Ixiamas… inhabited place”
  4. Note the latitude/longitude represented in “degrees minutes direction” (in the example of Ixiamas, La Paz, Bolivia it is Lat: 13 45 S and Long: 068 10 W) and write this information down on a sheet of paper
  5. Visit the Hebcal Custom Calendar latitude/longitude page at https://www.hebcal.com/hebcal?c=on;geo=pos
  6. Type the latitude and longitude into the form (13 degrees, 45 minutes South Latitude, 68 degrees 10 minutes West Longitude)
  7. Select the Time zone option specific to your location (see Wikipedia’s List of tz database time zones)
  8. Click “Get Calendar” button at the bottom of the form

Errata: candle-lighting time corrections

We’ve made changes to candle-lighting times for Shabbat and holidays that corrects an error we introduced a few months ago. Please accept our sincere apologies for this error.

Candle-lighting times have been adjusted 1-2 minutes earlier and now correctly reflect the correct time to light candles (40 minutes before sundown in Jerusalem, 18 minutes before sundown anywhere else).

Users who subscribe to Hebcal.com calendars via iPhone/iPad, Google Calendar, or Outlook.com should get the corrected candle-lighting times automatically when these applications perform their next refresh. The typical refresh cycle is approximately once a week.

If you downloaded or printed a calendar in the past, you may wish to return to the Hebcal.com website to download and/or print an updated calendar.

The error was caused when Hebcal.com moved to a new sunset calculation engine in the summer of 2013. The new sunset engine allows support for thousands of global cities and fixed long-standing issues with our handling of Daylight Saving Time outside of the USA. Sunset times are estimated from latitude and longitude, and generally have an accuracy of +/- 2 minutes except at extreme north or south latitudes.

Unfortunately, an arithmetic error in determining sunset for a given latitude/longitude was inadvertently introduced, which added an additional 1-2 minutes of error. This error was recently discovered and corrected.

When does Shabbat begin?

Shabbat begins 18 minutes before sundown on Friday night. In Jerusalem, Shabbat begins 40 minutes before sundown.

According to the United States Naval Observatory,

Sunrise or sunset is defined to occur when the geometric zenith distance of center of the Sun is 90.8333 degrees. That is, the center of the Sun is geometrically 50 arcminutes below a horizontal plane. For an observer at sea level with a level, unobstructed horizon, under average atmospheric conditions, the upper limb of the Sun will then appear to be tangent to the horizon. The 50-arcminute geometric depression of the Sun’s center used for the computations is obtained by adding the average apparent radius of the Sun (16 arcminutes) to the average amount of atmospheric refraction at the horizon (34 arcminutes). [USNO]