Standardization of Islamic Dates
Research and notes Part 1
by Shah Nawaz Khan, Free Lance Internet Journalist

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1.Origin of Islamic Calendar - Part 1
2. Related Verses of Holy Quran and Hadiths - Appendix
3. Facts about the moon - Appendix
4 Difference of Opinions in Interpreting Hadiths - Part 2
5. Fuqaha Positions on Regional and Global Sighting  - Part 3
 ‘Ikhtilaf vs. Ittihad al-Matali 
6. The Excellence of Friday

Origin of Islamic Calendar
A. When will the Islamic calendar overtake the Gregorian calendar? 
B. Brief History of Major Calendars 

At the dawn of Islam there were no watches or printed calendars and different dating systems were in use. Illiteracy and ignorance were so prevalent that many Ulemas refer to the era before revelation of Holy Quran as an era of ignorance!. To measure time the gnomon (shadow clock), a vertical stick or shaft that casts a shadow were being used. Methods of measuring hours in the absence of sunlight included the notched candle and the Chinese practice of burning a knotted rope. Other ancient devices include the hourglass and the water or sand clock, in which the flow of water or sand indicated passage of time. The mechanical clocks were developed in the 14th century AD.

The Jews in Arabia were using an unscientific Lunisolar calendar taken from the ancient Hebrew calendar. That has been modified and is the official calendar of the modern state of Israel and is used by Jewish people throughout the world as a religious calendar. 

The Islamic year has twelve months that are based on a lunar cycle.  Allah says in the Qur'an:

"The number of months in the sight of Allah is twelve (in a year) - so ordained by Him the day He created the heavens and the earth...." (9:36).

"It is He Who made the sun to be a shining glory, and the moon to be a light of beauty, and measured out stages for it, that you might know the number of years and the count of time.  Allah did not create this except in truth and righteousness.  And He explains His signs in detail, for those who understand" (10:5).

And in his final sermon before his death, the Prophet Muhammad said, among other things, "With Allah the months are twelve; four of them are holy; three of these are successive and one occurs singly between the months of Jumaada and Sha'ban."

Islamic months begin at sunset, on the day when the lunar crescent is visually sighted.  Because of centuries old practice of looking for the lunar crescent to determine if the new month has begun, different months begin and end on different weekdays in different countries/communities and usually a gap of one to three days occurs. 

The lunar year is approximately 354 days long, so the months rotate backward through the seasons and are not fixed to the Gregorian calendar.  The months of the Islamic year are:

1:  Muharram ["Forbidden" - it is one of the four months 
during which time it is forbidden to wage war or fight]

2:  Safar ["Empty" or "Yellow"]

3:  Rabia Awal ["First spring"]

4:  Rabia Thani ["Second spring"]

5:  Jumaada Awal ["First freezing"]

6:  Jumaada Thani ["Second freezing"]

7:  Rajab ["To respect" - this is another holy month when 
fighting is prohibited]

8:  Sha'ban ["To spread and distribute"]

9:  Ramadan ["Parched thirst" - this is the month of 
Islamic daytime fasting]

10: Shawwal ["To be light and vigorous"]

11:  Dhul-Qi'dah ["The month of rest" - another month 
when no warfare or fighting is allowed]

12:  Dhul-Hijjah ["The month of Hajj" - this is the month  of the annual pilgrimage to Mecca, again when no warfare or fighting is allowed]


"They ask thee concerning the New moons. Say: They are but signs to mark fixed periods of time in (the affairs of) men, and for Pilgrimage. .."AlQuran. 2.189



Holy Prophet (sws) laid great emphasis on unity of Ummah. It is simply illogical to believe that he wanted that different months of Islamic calendar begin and end in different cities and countries on different weekdays with a gap of one to three days and/or having a month of 29 days in one country and the same month same year having 30 days in another! 


It is fallacious to believe that just as prayer timings differ from place to place, Ramazan dates and Eid days can also differ. On the contrary just as Juma prayers are offered within 12 to 15 hours around the globe, we should be able to start and end Ramazan and other months and offer eid prayers within the same time constraint  – and not with the gap of one to three days. The day of Juma and beginning and end of Islamic months are global – not regional whereas only prayer timings are regional

Holy Quran does not mandate moon sighting by naked eyes. It was the logically correct interpretation of Muslim scholars of 10th century during the reign of Fatmid caliphs in Egypt that the advise of the Holy Prophet to start and end fasting by looking at the crescent was meant for people of that age as there were no printed calendars. And the use of Islamic Hijri calendar based on astronomical calculation came into advent in 10th century in order to maintain uniformity in the growing Muslim communities in different countries and continents. However, the orthodoxy of Saudi Arabia insisted and still insists that visibility of crescent at Ka’ba in Mecca is the criteria whereas in South Asian and Far Eastern countries the age-old tradition of regional moon sighting is continuing by the majority of Muslims. . 
The number of days in each month is adjusted throughout the year in accordance with each lunar cycle. The beginning of the Muslim year retrogresses through the solar year, completing a full cycle every 32 1/2 years.

A month consists of 29 days or 30 days depending upon appearance of crescent. The old traditional way, which is also mentioned in hadiths,  to determine, if a new month has begun was and still is in many communities,  to look for crescent every 29 days. If the crescent is seen the month ends on 29th day and the new month is begun from the same evening. If the crescent is not seen the month is regarded to have 30 days and the month ends the after sunset in the evening of 30th day.

In many Islamic countries like Saudi Arabia, the calendars are printed for civil or planning purposes. They are based on astronomical calculations for scientific estimates of the visibility of the lunar crescent earliest on earth or for a given location such as Mecca. In Saudi Arabia, Pakistan, India etc. the printed calendars are adjusted based on sighting the crescent on 29th day of the Islamic month for religious occasions. 

Beginning of Hijri Calendar
The Islamic calendar was first standardized in the year 638 C.E. by the Second Caliph, `Umar ibn Al-Khattab (RA) (592-644 AD.) as there were conflicting, dating systems being used. Hazrat Umar consulted  the senior companions of the Holy Prophet (sws) on the starting date of the Islamic chronology. It was agreed that the most appropriate starting point for the Islamic calendar was the Hijrah on Monday the 1st of Rabi Al-Awal, corresponding to 13 September 622 AD. The actual starting date for the Calendar was chosen (on the basis of purely lunar years, counting backwards) to be the first day of the first month (1 Muharram) of the year of the Hijrah. The Islamic (Hijri) calendar (with dates that fall within the Muslim Era) is usually abbreviated A.H. in Western languages from the latin Anno Hegirae, "in the year of the Hegira". Muhrram 1, 1 A.H. corresponds to July 16, 622 A. D. anno Domini of Christian ear..

The Hijrah, i.e.  the migration of the Prophet Muhammad (SWS) from Makkah to Madinah in September 622 C.E was turning point in the Islamic history. The Holy Prophet Muhammad  (SWS) in his preaching also advocated improving the lot of slaves, orphans, women, and the poor and giving up idolatry and embrace Islam. The infidels and idolaters offered him bribe to give up his preaching but he kept on preaching and thus the infidels were angered and became his enemies. They plotted to kill the Holy Prophet and thus he migrated secretly to Medina, a city about 300 km (about 186 mi) to the north.  This journey became known as the Hegira (Hijra) and marks the beginning of the Islamic calendar. 

When will the Islamic calendar overtake the Gregorian calendar? 
The moon moves around the earth. One month of lunar phases is 29 days, 12 hours, 44 minutes, and 2.8 seconds. The measurement of a solar year is based on one revolution of the earth around the sun. A solar or seasonal year contains 365 days, 5 hr, 48 min, and 45.5 sec. a little over 11 days more than the lunar year. 

Islamic calendar does not conform to seasons like the Gregorian calendar. Thus the month of Ramazan as also other months fall in every season as the Islamic year retrogresses through the solar year, completing a full cycle every 32 1/2 years. 

As the year in the Islamic calendar is about 11 days shorter than the year in the Christian calendar, the Islamic years are slowly gaining in on the Christian years. But it will take thousands of years before the two coincide. The 1st May of the year 20874 AD under the Gregorian calendar is estimated to be the 1st day of Jumaada Awal of the year 20874 of the Islamic calendar.  Let us hope the dooms day does not occur before that.

A Global Islamic Calendar based on astronomical calculations for appearance of crescent at Kaaba is the best way to standardize Islamic dating procedures. Visibility of moon on earth by naked eye is becoming more and more unpredictable due to global warming and pollution of atmosphere due to industrialization and space exploration. However, until the Saudi Authorities continue with the existing way of looking for new moon by naked eye, we may follow their calendar for the sake of unity and unification of Islamic calendar. After all we follow that when we go the Holy Land  for Haj or Umra.  

The following extract from the web site answers this question.

Brief History of Major Calendars 
Chinese, Jewish and Hindu calendars are the older than Islamic calendar. Jewish calendar was originated assuming the creation of the world at 3761 B.C. The earliest calendars based on lunar months eventually failed to agree with the seasons. A month occasionally had to be intercalated (added) to reconcile lunar months with the solar year.
A calendar that makes periodic adjustments of this kind is a lunisolar calendar. Such was the one used by the ancient Babylonians. The ancient Egyptians were the first to replace the lunar calendar with a calendar based on the solar year.

Holy Quran in verse 009.037 prohibited transposition or adjustments of months and in verse 055.005 indicates that the sun and the moon follow courses (exactly) computed. In verse 009.036 it is shown that the number of months in the sight of Allah is twelve (in a year)-  four of them are sacred: Click here to read the related verses and hadiths.

Hindu calendar is used by Hindus in India for their festivals and dating in its classic form from the fourth century A.D. The solar year is divided into 12 lunar months in accordance with the successive entrances of the sun into the signs of the zodiac, the months varying in length from 29 to 32 days.

For preparation of calendars the astronomers have been studying and measuring the the movements of moon and earth and the regular appearances of the sun and the moon. A day is reckoned as the average time taken for one rotation of the earth on its axis. The measurement of a year is based on one revolution of the earth around the sun and is called a seasonal, tropical, or solar year. A solar year contains 365 days, 5 hr, 48 min, and 45.5 sec. 

However, ancient peoples calculated a month as the time between two full moons. This measurement, called a synodic, or lunar month, resulted in a lunar year of 354 days, which is 11¼ days shorter than a solar year.

In modern calendars, the length of the months is approximately one twelfth of a year (28 to 31 days) and is adjusted to fit the 12 months into a solar year. The week comes from the Judeo-Christian tradition requiring rest from work and labor every seventh day i.e. Sunday for Christians. Muslims give special significance to Friday. See the hadith at the end of this chapter. 

The ancient Roman calendar was causing much confusion as the  officials responsible for adding days and months abused their authority to prolong their terms of office or to hasten or delay elections. In 45 BC Julius Caesar decided to use a purely solar calendar known as the Julian calendar. It established the order of the months and the days of the week as they exist in present-day calendars. It fixed the normal year at 365 days, and the leap year, every fourth year, at 366 days, with the extra day in February.

In 1582 Pope Gregory XIII modified the Julian Calendar and adopted  the Gregorian calendar, which provided that century years divisible evenly by 400 should be leap years, with 29 days in February. Thus, 1600 was a leap year, but 1700 and 1800 were common years. The Gregorian calendar is used today throughout most of the Western world and in different continents as well as for International trade and other social and political affairs. The Gregorian calendar is also called the Christian calendar because it uses the birth of Jesus Christ as a starting date. Dates of the Christian era are often labeled AD (Latin anno domini,”in the year of our Lord”) and BC (before Christ).

Updated 3rd November, 2006



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