If I use 72 minutes for Havdalah, why are Havdalah times ~90 minutes later than the previous day’s candle-lighting time?

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Shabbat begins 18 minutes before sundown on Friday night. Havdalah is 72 minutes after sundown on Saturday night. So in a given week, Havdalah time is typically 90 minutes after the previous day’s candle-lighting time (18 + 72 = 90). Sometimes there’s an extra minute or two difference, and that’s due to sunset actually differing… Read more »

How accurate are candle lighting times?

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Hebcal computes sunset based on an algorithm provided by the U.S. Naval Observatory (USNO). The USNO claims accuracy within 2 minutes except at extreme northern or southern latitudes. Comparison to local NWS charts for sunrise and sunset (which are cheap and easy to come by) shows that with the double precision calculations, the charts produced by… Read more »

How are candle lighting times determined from my zip code?

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Since candle lighting times are determined from latitude and longitude, a process called geocoding is used to determine the geographic position of a zip code. Our zip code database comes from the 1999 ZIP Code file from the U.S. Census Bureau’s Gazetteer project. The Gazetteer data from 1999 is much more complete than their data from… Read more »

What cities outside of the USA are available?

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Candle-lighting and Havdalah times are available for the following 54 cities: Ashdod (31d48′ N lat, 34d38′ E long, GMT +2:00, israel) Atlanta (33d45′ N lat, 84d23′ W long, GMT -5:00, usa) Austin (30d16′ N lat, 97d45′ W long, GMT -6:00, usa) Baghdad (33d14′ N lat, 44d22′ E long, GMT +3:00, eu) Beer Sheva (31d15′ N… Read more »