Explained: Four methods countries use to determine start dates for Ramadan, Eid 4

Countries across the Muslim world use different systems to determine the start of Hijri months, including Ramadan and Shawwal, which mark the beginning of fasting and Eid Al Fitr. While the Islamic calendar is based on the lunar cycle, there is no single globally unified method for confirming the start of each month.

The appearance of the crescent moon — known as Al Hilal — after sunset on the 29th day of the current Hijri month determines whether the new month begins the next day or after completing 30 days. Variations in geography, weather, and methodology often lead to different start dates between countries.

Here is a breakdown of the four main methods used.

Local physical sighting (Ru’yah)

This traditional method relies on direct human observation of the crescent moon after Maghrib prayer. Designated observers scan the western horizon using the naked eye and sometimes optical aids such as binoculars or telescopes.

Reported sightings are submitted to official religious authorities or moon-sighting committees, which verify the testimonies before making a public announcement. Many countries in the Middle East and beyond continue to follow this approach.

Astronomical calculations (Hisab)

Some countries depend primarily on astronomical data to determine the start of Hijri months. Scientists calculate moon conjunction, altitude, age, and visibility parameters to predict whether the crescent can be seen.

This method is typically used where weather or urban conditions make physical sighting difficult. Singapore, for example, has long adopted calculations due to frequent cloud cover and limited viewing horizons.

Standard reference method

Under this approach, communities follow the official announcement of another country or recognized Islamic authority rather than conducting their own local sighting. This is often the nearest Muslim-majority country or a central reference location such as Makkah.

Muslims in places without formal religious institutions — such as temporary residents in remote regions — may rely on this method for consistency.

Hybrid approach

A number of countries combine scientific calculations with physical sighting. Astronomical forecasts are used to determine whether visibility is possible and to guide observers, but the final decision still depends on confirmed sighting reports approved by authorities.

Calculations support but do not replace the formal declaration process in this model.

Why dates differ between countries

Hijri month start dates can vary because crescent visibility depends on location, weather conditions, and time zones. The moon may be visible in one region but not another on the same evening due to cloud cover, horizon clarity, latitude, and longitude.

Differences in national policy — whether calculation-based, sighting-based, or hybrid — also contribute to variations in Ramadan and Eid start dates.

Months with highest public significance

While moon sighting occurs every Hijri month, several months draw particular attention:

1. Ramadan: Start of the fasting month

2. Shawwal: Begins with Eid Al Fitr

3. Dhul Hijjah: Includes Hajj rites, Day of Arafat, and Eid Al Adha

4. Muharram: First month of the Hijri year, includes Ashoura

5. Rabi Al Awwal: Month in which the Prophet Muhammad’s (PBUH) birthday is observed by many Muslims

Special case: Hajj timing

For Hajj, pilgrims worldwide follow the Dhul Hijjah moon sighting announced in Saudi Arabia, since the rituals are tied to specific dates in Makkah, including the standing at Arafat on the 9th day.

UAE moon-sighting infrastructure

In the UAE, crescent sightings are supported by multiple observatories and official committees. Recent years have also seen the use of advanced tools such as drones and AI-assisted imaging to help confirm sightings.