Shabbat begins at sunset on Friday, but the candle-lighting time is about 18 minutes before sunset. Why?
Shabbat begins at sundown, and from that time on it is forbidden to perform certain activities (including lighting Shabbat candles). The Shulchan Aruch states that one should “add from the weekday onto Shabbat (Lehosif me’kodesh al chol)” . Mean, addition to Shabbat. It seems that the custom of 18 minutes arises from the Halachic time measure called a “Hiluch Mil” which means the time it takes to walk a Mil. The word “Mil” is derived from the Roman “Miliarium” which was 1000 paces (approximately 3000 feet). According to the ancient American commercial, this would be the amount one would walk for a Camel. The Halachic Mil and the Roman Miliarium differ only slightly in length. The time it takes to walk a Mil is 18 minutes.
What is the Candle Time in my city?
How to Calculate it?
Here’s the formula for sunset time based on date, latitude, and longitude (click to view the full calculation):