Why Islamic Dates Differ Between Countries

Almost every year, some countries begin Ramadan or celebrate Eid a day before others. This is not a mistake in anyone's calendar: it follows from how the start of a Hijri month is decided. There are three main reasons.

1. Sighting or calculation

Some authorities begin a month only after the new crescent has been seen, following the hadith "start fasting on seeing it" (Sahih al-Bukhari 1909). Others accept astronomical calculation, either to confirm that a sighting was possible or to fix the dates in advance. A calculated calendar such as Umm al-Qura can begin a month on an evening when the crescent is above the horizon but still too faint to see, so it often runs a day ahead of sighting-based calendars.

2. Local or global sighting

Scholars have long discussed whether a sighting in one place applies everywhere. Under local sighting, each country or region follows its own sky; under global sighting, a credible sighting anywhere, or in a reference country such as Saudi Arabia, is followed by everyone. Communities make different choices, so neighbouring mosques in the same city sometimes celebrate Eid on different days.

3. The crescent appears first in the west

The crescent becomes easier to see as it gets older and as the sun sets later. On the 29th evening it may be invisible across Asia but visible in West Africa or the Americas a few hours later. Countries that rely on local sighting in the east will then start the month a day later than those further west.

How large can the difference be?

Usually one day, occasionally two when a country waits for its own sighting in poor weather. A month cannot be longer than 30 days, so the differences never accumulate from month to month.

What should you follow?

For acts of worship, follow your local mosque, scholars or national religious authority. HijriTime shows dates from the Umm al-Qura calendar, which matches the official calendar of Saudi Arabia, and reminds you on every page that the date may be one day later where the month starts with a local sighting. To see how the crescent is observed, read how the new crescent moon is sighted.