Why Eid is marked "expected"

A month that starts with the moon

Each month of the Islamic calendar begins when the new crescent moon is seen in the western sky after sunset on the 29th day. If it is seen, the next day is the 1st of the new month. If it is not seen, because of cloud or because the moon is still too thin and too close to the sun, the month runs to 30 days. So every month is 29 or 30 days, and which one is not known until the evening of the 29th.

Why it cannot be printed in advance

Astronomers can calculate, years ahead, when the moon will be new and roughly when the crescent should become visible. Calendars such as Umm al-Qura, used in Saudi Arabia for civil purposes, are built from such calculations, and this site uses it to work out its expected dates. But in Afghanistan the start of Ramadan and the Eids is announced after a sighting of the moon is reported and accepted, and that can fall a day either side of the calculation. In some years, different parts of the country have begun fasting or celebrated Eid on different days.

What "expected" means here

• The date shown is the calculated one, usually right and sometimes a day out.
• The official date is settled on the evening before, often late, after the sighting is confirmed.
• Every holiday counted from a lunar month, such as Ashura on the 10th of Muharram, moves with that month's start.
• Holidays set in the solar or Gregorian calendar never move, and are shown without the word.

Why the dates walk through the seasons

A lunar year is about eleven days shorter than a solar one. So each year Ramadan and the Eids come about eleven days earlier by the solar calendar, and over some 33 years they pass through every season. A summer Ramadan with long hot days slowly becomes a winter one.

Plan for the expected date, and keep the day after free. When the sighting is announced, the announcement is the authority.