Islamic calendar

This article is about the lunar Hijri calendar. For the solar calendar whose first year is fixed to the Hijra, see Solar Hijri calendar.

Islamic Calendar stamp issued at King Khaled airport (10 Rajab 1428)

The Islamic calendar, Muslim calendar or Hijri calendar (AH) is a lunar calendar consisting of 12 months in a year of 354 days.

It is used to date events in many Muslim countries (concurrently with the Gregorian calendar), and used by Muslims everywhere to determine the proper days on which to observe the annual fasting, to attend Hajj, and to celebrate other Islamic holidays and festivals.

The first year was the Islamic year beginning in AD 622 during which the emigration of Muhammad from Mecca to Medina, known as the Hijra, occurred. Each numbered year is designated either "H" for Hijra or "AH" for the Latin Anno Hegirae ("in the year of the Hijra"); hence, Muslims typically call their calendar the Hijri calendar.

The current Islamic year is 1437 AH. In the Gregorian calendar, 1437 AH runs from approximately 14 October 2015 to 2 October 2016.

Months

Four of the twelve Hijri months are considered sacred: Rajab (7), and the three consecutive months of Dhū al-Qaʿdah (11), Dhu al-Ḥijjah (12) and Muḥarram (1). Because the lunar calendar lags behind the solar calendar by about ten days every year, months of the Islamic calendar fall in different parts of the Gregorian calendar each year. The cycle repeats every 33 years.

No.	Name	Arabic	Meaning	Note
1	Muḥarram	مُحَرَّم	forbidden	A sacred month, so called because battle and all kinds of fighting are forbidden (ḥarām) during this month. Muḥarram includes ʿĀshūrāʾ, the tenth day.
2	Ṣafar	صَفَر	void	Supposedly named thus because pre-Islamic Arab houses were empty this time of year while their occupants gathered food. Another account relates that they used to loot the houses of their enemies after defeating them in battle, leaving nothing behind.
3	Rabīʿ al-awwal	رَبيع الأوّل	the first spring	Also means to graze, because they used to graze their cattle during this month.
4	Rabīʿ al-thānī	رَبيع الثاني	the second spring
5	Jumādá al-ūlá	جُمادى الأولى	the first of parched land	Often considered the pre-Islamic summer. Jumādá may also be related to a verb meaning "to freeze" and another account relates that water would freeze during this time of year.
6	Jumādá al-ākhirah	جُمادى الآخرة	the last of parched land
7	Rajab	رَجَب	respect, honor	This is the second sacred month in which fighting is forbidden. Rajab may also be related to a verb meaning "to remove", so called because pre-Islamic Arabs would remove the heads of their spears and refrain from fighting.
8	Shaʿbān	شَعْبان	scattered	Marked the time of year when Arab tribes dispersed to find water. Shaʿbān may also be related to a verb meaning "to be in between two things". Another account relates that it was called thus because the month lies between Rajab and Ramaḍān.
9	Ramaḍān	رَمَضان	burning heat	Supposedly so called because of high temperatures caused by the excessive heat of the sun. Ramaḍān is the most venerated month of the Hijri calendar. During this time, Muslims must fast from pre-dawn till sunset and should give charity to the poor and needy.
10	Shawwāl	شَوّال	raised	She-camels would normally be in calf at this time of year and raise their tails.
11	Dhū al-Qaʿdah	ذوالقعدة	the one of truce/sitting	This is a holy month during which war is banned. People are allowed to defend themselves if attacked.
12	Dhū al-Ḥijjah	ذوالحجة	the one of pilgrimage	The holy month in which the annual Muslim pilgrimage to Mecca (the Ḥajj) occurs and during which war is banned.

Length of months

Each month of the Islamic calendar commences on the birth of the new lunar cycle. Traditionally this is based on actual witnessing of the crescent marking the end of the previous lunar cycle and hence the previous month thereby beginning the new month. Consequently, each month can have 29 or 30 days depending on the visibility of the moon, astronomical positioning of the earth and weather conditions. However, certain sects and groups, most notably Dawoodi Bohra Muslims and Shia Ismaili Muslims use a tabular Islamic calendar (see section below) in which odd-numbered months have thirty days (and also the twelfth month in a leap year) and even months have 29.

Days of the week

In Arabic, the "first day" of the week corresponds with Sunday of the planetary week. The Islamic weekdays, like those in the Hebrew and Baha'i calendars, begin at sunset. The Christian liturgical day, kept in monasteries, begins with vespers (see vesper), which is evening, in line with the other Abrahamic traditions. Christian and planetary weekdays begin at the following midnight. Muslims gather for worship at a mosque at noon on "gathering day" (Yawm al-Jumʿah, yawm يوم meaning "day") which corresponds with Friday. Thus "gathering day" is often regarded as the weekly day of rest. This is frequently made official, with many Muslim countries adopting Friday and Saturday (e.g., Egypt, Saudi Arabia) or Thursday and Friday as official weekends, during which offices are closed; other countries (e.g., Iran) choose to make Friday alone a day of rest. A few others (e.g., Turkey, Pakistan) have adopted the Saturday-Sunday weekend while making Friday a working day with a long midday break to allow time off for worship.

	1	2	3	4	5	6	7
Arabic	(Yawm) al-Aḥad الأحد "First day"	(Yawm) al-Ithnayn الإثنين "Second day"	(Yawm) al-Thulāthāʾ الثلاثاء "Third day"	(Yawm) al-Arbaʿāʾ الأربعاء "Fourth day"	(Yawm) al-Khamīs الخميس "Fifth day"	(Yawm) al-Jumʿah الجمعة "Gathering day"	(Yawm) as-Sabt السبت "Day of Rest"
English	Sunday	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday
Albanian	E dielë	E hënë	E martë	E mërkurë	E enjte	E premte (E xhuma)	E shtunë
Bengali	রবিবার Robibar	সোমবার Shombar	মঙ্গলবার Monggolbar	বুধবার Budhbar	বৃহস্পতিবার Brihôshpotibar	শুক্রবার Shukrobar	শনিবার Shonibar
Bosnian	Nedjelja	Ponedjeljak	Utorak	Srijeda	Četvrtak	Petak / (Džuma)	Subota
Filipino	Linggó	Lunes	Martes	Miyérkules	Huwebes	Biyernes	Sábado
Hausa	Lahadi	Litinin	Talata	Laraba	Alhamis	Juma'a	Asabar
Hebrew	יום ראשון Yom Rishon "First Day"	יום שני Yom Sheni "Second Day"	יום שלישי Yom Shlishi "Third Day"	יום רביעי Yom Revi'i "Fourth Day"	יום חמישי Yom Khamishi "Fifth Day"	יום ששי Yom Shishi "Sixth Day"	יום שבת Yom Shabbat "Day of Rest"
Hindi	रविवार Ravivaar इतवार Itvaar	सोमवार Somvaar	मंगलवार Mangalvaar	बुधवार Budhvaar	गुरुवार Guruvaar बृहस्पतिवार Brahaspativaar	शुक्रवार Shukravaar	शनिवार Shanivaar
Indonesian	Minggu	Senin	Selasa	Rabu	Kamis	Jumat	Sabtu
Kannada	ಭಾನುವಾರ Bhaanuvaara ರವಿವಾರ Ravivaara ಆದಿತ್ಯವಾರ Aadityavaara	ಸೋಮವಾರ Somavaara	ಮಂಗಳವಾರ Mangalavaara	ಬುಧವಾರ Budhavaara	ಗುರುವಾರ Guruvaara	ಶುಕ್ರವಾರ Shukravaara	ಶನಿವಾರ Shanivaara
Kashmiri	A'ath'war	Chender'r'war	Bo'um'war	Bo'dh'war	Bres'war	Jum'mah	Butt'war alah
Kurdish	یەکشەممە Yekşem	دووشەممە Duşem	سێشەممە Sêşem	چوارشەممە Çarşem	پێنجشەممە Pêncşem	ھەینی Heynî	شەممە Şemî
Malay	Ahad	Isnin	Selasa	Rabu	Khamis	Jumaat	Sabtu
Malayalam	ഞായര്‍ ñaayar	തിങ്കള്‍ thiṅkal	ചൊവ്വ chovva	ബുധന്‍ budhan	വ്യാഴം vyazham	വെള്ളി veḷḷi	ശനി shani
Maltese	Il-Ħadd	It-Tnejn	It-Tlieta	L-Erbgħa	Il-Ħamis	Il-Ġimgħa	Is-Sibt
Nepali	आइतबार Aaitabaar	सोमबार Sombaar	मंगलबार Manglabaar	बुधबार Budhabaar	बिहीबार Bihibaar	शुक्रबार Shukrabaar	शनिबार Shanibaar
Pashto	يوه نۍ Yawanay اتوار Itwar	دوه نۍ Dwanay ګل Gul	منځنۍ Manzanay نھہ Nahia	څلنۍ Salanay شورو Shoro	پنځنۍ Panzanay زيارت Ziyarat	ادینه Adina جمعه Juma	سابتو Sabtu خالي Khalee
Persian	یکشنبه Yek-Shanbeh	دوشنبه Do-Shanbeh	سه شنبه Seh-Shanbeh	چهارشنبه Chahar-Shanbeh	پنجشنبه Panj-Shanbeh	جمعه Jom‘e آدينه Adineh	Hafta شنبه Shanbeh
Punjabi	ਐਤਵਾਰ Aitvaar	ਸੋਮਵਾਰ Somvaar	ਮੰਗਲਵਾਰ Mangalvaar	ਬੁੱਧਵਾਰ Buddhavaar	ਵੀਰਵਾਰ Veervaar	ਸ਼ੁੱਕਰਵਾਰ Shukkarvaar	ਛਨਿੱਛਰਵਾਰ Chhanichharvaar
Pushto	اتوار Itwaar	ګل Peer	نهي Nahee	چهارشنبه Chahar-Shanbeh	زيارت Ziyarat	جمعہ Juma‘h	خالي Khalee
Sindhi	آچر Aacher आरितवार āritavāra	سومر Soomar सूमर sūmara	انگارو Angaro मंगल maṅgala	أربع Arbba बु॒धर b̤udhara	خميس Khameesa विस्पति vispati	جمعو Jum'o जुमो jumho	ڇنڇر Chhanchher छंछर chhaṅchhara
Somali	Axad احد	Isniin	Talaado	Arbaco أربعو	Khamiis	Jimco	Sabti
Tamil	ஞாயிற்றுக்கிழமை gyayitrukkilamai	திங்கட்கிழமை thingatkkilamai	செவ்வாய்க்கிழமை sevvaikkilamai	புதன்கிழமை buthankilamai	வியாழக்கிழமை viyalakkilamai	வெள்ளிக்கிழமை vellikkilamai	சனிக்கிழமை sanikkilamai
Telugu	ఆదివారం Aadivaaram	సోమవారం Somavaaram	మంగళవారం Mangalavaaram	బుధవారం Budhavaaram	గురువారం Guruvaaram	శుక్రవారం Shukravaaram	శనివారం Shanivaaram
Turkish	Pazar	Pazartesi	Salı	Çarşamba	Perşembe	Cuma	Cumartesi
Urdu	اتوار Itwār	پير Pīr	منگل Mangal	بدھ Budh	جمعرات Jum‘erāt	جمعہ Jum‘ah	ہفتہ Haftah
Yorùbá	Ọjọ́ Àìkú	Ọjọ́ Ajé	Ọjọ́ Ìṣẹ́gun	Ọjọ́-rírú Ọjọ́rú	Ọjọ́bọ̀ Ọjọ́ Àṣẹ̀ṣẹ̀ Dáyé	Ọjọ́ Ẹtì	Ọjọ́ Àbá Mẹ́ta
Sinhala	ඉරිදා Iridá	සඳුදා Sandudá	අඟහරුවාදා Angaharuwádá	බදාදා Badadá	බ්‍රහස්පතින්දා Brahaspathindá	සිකුරාදා Sikurádá	සෙනසුරාදා Senasurádá
Dhivehi	އާދީއްތަ Aadheeththa	ހޯމަ Hoama	އަންގާރަ Angaara	ބުދަ Budha	ބުރާސްފަތި Buraasfathi	ހުކުރު Hukuru	ހޮނިހިރު Honihiru

History

Pre-Islamic calendar

Main article: Pre-Islamic calendar

Inscriptions of the ancient South Arabian calendars reveal the use of a number of local calendars. At least some of these calendars followed the lunisolar system. For Central Arabia, especially Mecca, there is a lack of epigraphical evidence but details are found in the writings of Muslim authors of the Abbasid era. Both al-Biruni and al-Mas'udi suggest that the Ancient Arabs used the same month names as the Muslims, though they also record other month names used by the pre-Islamic Arabs.

It is well known that Hajj was originally an equinoctial festival and research on the pre-Islamic calendar has been summarized in recent Islamic and secular scholarship which equates the pre-Islamic months from Muharram to Dhu al-Hijjah with the Hebrew religious months of Iyyar to Nisan respectively (Ramadan corresponding to the Fast of Adam in Tevet) rather than Nisan to Adar as might otherwise be presumed. In stark opposition to this opinion however, subsequent Christian then Jewish scholars have both tried to equate the pre-Islamic months from Muharram to Jumādā ath-Thāniya at least with the Hebrew months of Tishrei to Adar I respectively. Nevertheless, the Islamic position equating Nisan with Dhū al-Ḥijja has prevailed. For a comparison between the Islamic and pre-Islamic months, see Islamic and Jahili months.

The Islamic tradition is unanimous in stating that Arabs of Tihamah, Hejaz, and Najd distinguished between two types of months, permitted (ḥalāl) and forbidden (ḥarām) months. The forbidden months were four months during which fighting is forbidden, listed as Rajab and the three months around the pilgrimage season, Dhu al-Qa‘dah, Dhu al-Hijjah, and Muharram. Information about the forbidden months is also found in the writings of Procopius, where he describes an armistice with the Eastern Arabs of the Lakhmid al-Mundhir which happened in the summer of 541 AD. However, Muslim historians do not link these months to a particular season. The Qur'an links the four forbidden months with Nasī’, a word that literally means "postponement". According to Muslim tradition, the decision of postponement was administered by the tribe of Kinanah, by a man known as the al-Qalammas of Kinanah and his descendants (pl. qalāmisa).

Different interpretations of the concept of Nasī’ have been proposed. Some scholars, both Muslim and Western, maintain that the pre-Islamic calendar used in Central Arabia was a purely lunar calendar similar to the modern Islamic calendar. According to this view, Nasī’ is related to the pre-Islamic practices of the Meccan Arabs, where they would alter the distribution of the forbidden months within a given year without implying a calendar manipulation. This interpretation is supported by Arab historians and lexicographers, like Ibn Hisham, Ibn Manzur, and the corpus of Qur'anic exegesis. It is also corroborated by an early Sabaic inscription, where a religious ritual was "postponed" (ns'ʾw) due to war. According to the context of this inscription, the verb ns'ʾ has nothing to do with intercalation, but only with moving religious events within the calendar itself. The similarity between the religious concept of this ancient inscription and the Qur'an suggests that non-calendaring postponement is also the Qur'anic meaning of Nasī’. Thus the Encyclopaedia of Islam concludes that the "The Arabic system of [Nasī’] can only have been intended to move the Hajj and the fairs associated with it in the vicinity of Mecca to a suitable season of the year. It was not intended to establish a fixed calendar to be generally observed."

Others concur that it was originally a lunar calendar, but suggest that about 200 years before the Hijra it was transformed into a lunisolar calendar containing an intercalary month added from time to time to keep the pilgrimage within the season of the year when merchandise was most abundant. This interpretation was first proposed by the medieval Muslim astrologer and astronomer Abu Ma'shar al-Balkhi, and later by al-Biruni, al-Mas'udi, and some Western scholars. This interpretation considers Nasī’ to be a synonym to the Arabic word for "intercalation" (kabīsa). The Arabs, according to one explanation mentioned by Abu Ma'shar, learned of this type of intercalation from the Jews. The Jewish Nasi was the official who decided when to intercalate the Jewish calendar. Scholars have suggested that the Arabic system was to intercalate three months in eight years (nine in 24), seven in nineteen or eleven in thirty. All these values are in agreement with the cycle of the seasons which requires on average an addition of one month every 33 or 34 months.

Some writers have suggested that the first intercalation doubled the first month Muharram, then on the next adjustment the second month Safar was doubled, continuing until the intercalation had passed through all twelve months of the year and returned to Muharram, when it was repeated. This is explained by one scholar as the writer simply explaining the intercalated calendar in terms of the fixed calendar, which his readers were familiar with. The Qu'ran makes it clear that in intercalary years the number of months was expanded from its usual twelve (see next section). It is affirmed that the divinely ordained number of the months is twelve.

What dates we can fix confirm this picture. Traditionally Muhammad was born in the spring of the year of the elephant (AD 570) on Monday, 12 Rabi'I. This would equate to 2 June, making Muharram equal to Nisan. In the year of the Hejira (AD 622) Muhammad traditionally left Mecca on Sunday night, the start of 24 Safar. This equates to Sunday, 9 May and points to Muharram starting on 18 March, again equivalent to Nisan. He entered Medina traditionally on Monday, 8 Rabi'I (24 May). There he found the Jews observing an important holy day. From the reference to Moses and the Exodus this holy day can be identified with the Feast of Weeks, which is observed on the sixth and seventh days of the third Jewish month. Muhammad's son Ibrahim was traditionally born in Dhu al - Hijjah, the twelfth month, which was the month of the pilgrimage, in AD 630. He is believed to have died in AD 632, possibly at the age of one year ten months and six days or one year ten months and eight days. The date of his death coincided with a solar eclipse. This fixes the date, 29 Shawwal AH 10, as 27 January. With no intercalation the following Muharram corresponds to Nisan, and also Muharram in the present calendar, that being the end of intercalation in the Islamic calendar.

Prohibiting Nasī’

Further information: Nasi'

Muhammad prohibiting Nasī’. Found in an illustrated copy of Al-Bīrūnī's The Remaining Signs of Past Centuries (17th-century copy of an early 14th-century Ilkhanid manuscript).

In the tenth year of the Hijra, as documented in the Qur'an (Sura At-Tawba (9):36–37), God revealed the "prohibition of the Nasī’".

The number of the months, with God, is twelve in the Book of God, the day that He created the heavens and the earth; four of them are sacred. That is the right religion. So wrong not each other during them. And fight the unbelievers totally even as they fight you totally and know that God is with the godfearing. Know that intercalation (nasi) is an addition to disbelief. Those who disbelieve are led to error thereby, making it lawful in one year and forbidden in another in order to adjust the number of (the months) made sacred by God and make the sacred ones permissible. The evil of their course appears pleasing to them. But God gives no guidance to those who disbelieve.

— Sura 9 ("At-Tawba"), ayat 36–37

The prohibition of Nasīʾ would presumably have been announced when the intercalated month had returned to its position just before the month of Nasi' began. If Nasīʾ meant intercalation, then the number and the position of the intercalary months between 1 AH and 10 AH are uncertain; Western calendar dates commonly cited for key events in early Islam such as the Hijra, the Battle of Badr, the Battle of Uhud and the Battle of the Trench, should be viewed with caution as they might be in error by one, two or even three lunar months.

This prohibition was mentioned by Muhammad during the farewell sermon which was delivered on 9 Dhu al-Hijjah 10 AH (Julian date Friday 6 March, AD 632) on Mount Arafat during the farewell pilgrimage to Mecca.

Certainly the Nasi’ is an impious addition, which has led the infidels into error. One year they authorise the Nasi’, another year they forbid it. They observe the divine precept with respect to the number of the sacred months, but in fact they profane that which God has declared to be inviolable, and sanctify that which God has declared to be profane. Assuredly time, in its revolution, has returned to such as it was at the creation of the heavens and the earth. In the eyes of God the number of the months is twelve. Among these twelve months four are sacred, namely, Rajab, which stands alone, and three others which are consecutive.

— Translated by Sherrard Beaumont Burnaby

The three successive sacred (forbidden) months mentioned by Prophet Muhammad (months in which battles are forbidden) are Dhu al-Qa‘dah, Dhu al-Hijjah, and Muharram, months 11, 12, and 1. The single forbidden month is Rajab, month 7. These months were considered forbidden both within the new Islamic calendar and within the old pagan Meccan calendar

Year numbering

Main article: Hijri year

In pre-Islamic Arabia, it was customary to identify a year after a major event which took place in it. Thus, according to Islamic tradition, Abraha, governor of Yemen, then a province of the Christian Kingdom of Aksum (Ethiopia), attempted to destroy the Kaaba with an army which included several elephants. The raid was unsuccessful, but that year became known as the Year of the Elephant, during which Muhammad was born (sura al-Fil). Most equate this to the year AD 570, but a minority use AD 571.

The first ten years of the Hijra were not numbered, but were named after events in the life of Muhammad according to Abū Rayḥān al-Bīrūnī:

1. The year of permission.
2. The year of the order of fighting.
3. The year of the trial.
4. The year of congratulation on marriage.
5. The year of the earthquake.
6. The year of enquiring.
7. The year of gaining victory.
8. The year of equality.
9. The year of exemption.
10. The year of farewell.

In AD 638 (17 AH), Abu Musa Ashaari, one of the officials of the Caliph Umar in Basrah, complained about the absence of any years on the correspondence he received from Umar, making it difficult for him to determine which instructions were most recent. This report convinced Umar of the need to introduce an era for Muslims. After debating the issue with his counsellors, he decided that the first year should include the date of Muhammad's arrival at Medina (known as Yathrib, before Muhammad's arrival). Uthman ibn Affan then suggested that the months begin with Muharram, in line with the established custom of the Arabs at that time. The years of the Islamic calendar thus began with the month of Muharram in the year of Muhammad's arrival at the city of Medina, even though the actual emigration took place in Safar and Rabi' I. Because of the Hijra, the calendar was named the Hijra calendar.

The first day of the first month of the Islamic calendar (1 Muharram 1 AH) was set to the first new moon after the day the Prophet moved from Quba' to Medina (originally 26 Rabi' I on the pre-Islamic calendar) i.e., Friday, 16 July AD 622, the equivalent civil tabular date (same daylight period) in the Julian calendar. The Islamic day began at the preceding sunset on the evening of 15 July. This Julian date (16 July) was determined by medieval Muslim astronomers by projecting back in time their own tabular Islamic calendar, which had alternating 30- and 29-day months in each lunar year plus eleven leap days every 30 years. For example, al-Biruni mentioned this Julian date in the year AD 1000. Although not used by either medieval Muslim astronomers or modern scholars to determine the Islamic epoch, the thin crescent moon would have also first become visible (assuming clouds did not obscure it) shortly after the preceding sunset on the evening of 15 July, 1.5 days after the associated dark moon (astronomical new moon) on the morning of 14 July.

Though Cook and Crone in Hagarism: The Making of the Islamic World cite a coin from 17 AH, the first surviving attested use of a Hijri calendar date alongside a date in another calendar (Coptic) is on a papyrus from Egypt in 22 AH, PERF 558.

Astronomical considerations

The Islamic calendar is not to be confused with a lunar calendar that is based on astronomical calculations. The latter is based on a year of 12 months adding up to 354.37 days. Each lunar month begins at the time of the monthly "conjunction", when the Moon is located on a straight line between the Earth and the Sun. The month is defined as the average duration of a revolution of the Moon around the Earth (29.53 days). By convention, months of 30 days and 29 days succeed each other, adding up over two successive months to 59 full days. This leaves only a small monthly variation of 44 minutes to account for, which adds up to a total of 24 hours (i.e., the equivalent of one full day) in 2.73 years. To settle accounts, it is sufficient to add one day every three years to the lunar calendar, in the same way that one adds one day to the Gregorian calendar every four years. The technical details of the adjustment are described in Tabular Islamic calendar.

The Islamic calendar, however, is based on a different set of conventions. Each month has either 29 or 30 days, but usually in no discernible order. Traditionally, the first day of each month is the day (beginning at sunset) of the first sighting of the hilal (crescent moon) shortly after sunset. If the hilal is not observed immediately after the 29th day of a month (either because clouds block its view or because the western sky is still too bright when the moon sets), then the day that begins at that sunset is the 30th. Such a sighting has to be made by one or more trustworthy men testifying before a committee of Muslim leaders. Determining the most likely day that the hilal could be observed was a motivation for Muslim interest in astronomy, which put Islam in the forefront of that science for many centuries.

This traditional practice is still followed in the overwhelming majority of Muslim countries. Each Islamic state proceeds with its own monthly observation of the new moon (or, failing that, awaits the completion of 30 days) before declaring the beginning of a new month on its territory. But, the lunar crescent becomes visible only some 17 hours after the conjunction, and only subject to the existence of a number of favourable conditions relative to weather, time, geographic location, as well as various astronomical parameters. Given the fact that the moon sets progressively later than the sun as one goes west, with a corresponding increase in its "age" since conjunction, Western Muslim countries may, under favorable conditions, observe the new moon one day earlier than eastern Muslim countries. Due to the interplay of all these factors, the beginning of each month differs from one Muslim country to another, during the 48 h period following the conjunction. The information provided by the calendar in any country does not extend beyond the current month.

A number of Muslim countries try to overcome some of these difficulties by applying different astronomy-related rules to determine the beginning of months. Thus, Malaysia, Indonesia, and a few others begin each month at sunset on the first day that the moon sets after the sun (moonset after sunset). In Egypt, the month begins at sunset on the first day that the moon sets at least five minutes after the sun. A detailed analysis of the available data shows, however, that there are major discrepancies between what countries say they do on this subject, and what they actually do. In some instances, what a country says it does is impossible.

Theological considerations

If the Islamic calendar were prepared using astronomical calculations, Muslims throughout the Muslim world could use it to meet all their needs, the way they use the Gregorian calendar today. But, there are divergent views on whether it is licit to do so.

A majority of theologians oppose the use of calculations (beyond the constraint that each month must be not less than 29 nor more than 30 days) on the grounds that the latter would not conform with Muhammad's recommendation to observe the new moon of Ramadan and Shawal in order to determine the beginning of these months.

However, some jurists see no contradiction between Muhammad's teachings and the use of calculations to determine the beginnings of lunar months. They consider that Muhammad's recommendation was adapted to the culture of the times, and should not be confused with the acts of worship.

Thus the jurists Ahmad Muhammad Shakir and Yusuf al-Qaradawi both endorsed the use of calculations to determine the beginning of all months of the Islamic calendar, in 1939 and 2004 respectively. So did the Fiqh Council of North America (FCNA) in 2006 and the European Council for Fatwa and Research (ECFR) in 2007.

The major Muslim associations of France also announced in 2012 that they would henceforth use a calendar based on astronomical calculations, taking into account the criteria of the possibility of crescent sighting in any place on Earth. But, shortly after the official adoption of this rule by the French Council of the Muslim Faith (CFCM) in 2013, the new leadership of the association decided, on the eve of ramadan 2013, to follow the Saudi announcement rather than to apply the rule just adopted. This resulted in a division of the Muslim community of France, with some members following the new rule, and others following the Saudi announcement.

Fatimid Dawoodi Bohra and Qutbi Bohra a sub sect of Dawoodi Bohra follow the tabular Islamic calendar (see section below) prepared on the basis of astronomical calculations from the days of Fatimid imams.

Astronomical 12-moon calendars

Islamic Calendar of Turkey

Turkish Muslims use an Islamic calendar which is calculated several years in advance (currently up to 1444 AH/2022 CE) by the Turkish Presidency of Religious Affairs (Diyanet İşleri Başkanlığı). From 1 Muharrem 1400 AH (21 November 1979) until 29 Zilhicce 1435 (24 October 2014) the computed Turkish lunar calendar was based on the following rule: “The lunar month is assumed to begin on the evening when, within some region of the terrestrial globe, the computed centre of the lunar crescent at local sunset is more than 5° above the local horizon and (geocentrically) more than 8° from the Sun.” In the current rule the (computed) lunar crescent has to be above the local horizon of Ankara at sunset.

Saudi Arabia's Umm al-Qura calendar

Saudi Arabia uses the sighting method to determine the beginning of each month of the Hijri calendar. Since AH 1419 (1998/99) several official hilal sighting committees have been set up by the government to determine the first visual sighting of the lunar crescent at the beginning of each lunar month. Nevertheless, the religious authorities also allow the testimony of less experienced observers and thus often announce the sighting of the lunar crescent on a date when none of the official committees could see it.

The country also uses the Umm al-Qura calendar, based on astronomical calculations, but this is restricted to administrative purposes. The parameters used in the establishment of this calendar underwent significant changes over the past decade.

Before AH 1420 (before 18 April 1999), if the moon's age at sunset in Riyadh was at least 12 hours, then the day ending at that sunset was the first day of the month. This often caused the Saudis to celebrate holy days one or even two days before other predominantly Muslim countries, including the dates for the Hajj, which can only be dated using Saudi dates because it is performed in Mecca.

For AH 1420–22, if moonset occurred after sunset at Mecca, then the day beginning at that sunset was the first day of a Saudi month, essentially the same rule used by Malaysia, Indonesia, and others (except for the location from which the hilal was observed).

Since the beginning of AH 1423 (16 March 2002), the rule has been clarified a little by requiring the geocentric conjunction of the sun and moon to occur before sunset, in addition to requiring moonset to occur after sunset at Mecca. This ensures that the moon has moved past the sun by sunset, even though the sky may still be too bright immediately before moonset to actually see the crescent.

In 2007, the Islamic Society of North America, the Fiqh Council of North America and the European Council for Fatwa and Research announced that they will henceforth use a calendar based on calculations using the same parameters as the Umm al-Qura calendar to determine (well in advance) the beginning of all lunar months (and therefore the days associated with all religious observances). This was intended as a first step on the way to unify, at some future time, Muslims' calendars throughout the world.

Other calendars using the Islamic era

The Solar Hejri is a solar calendar used in Iran and Afghanistan which counts its years from the Hijra or migration of Muhammad from Mecca to Medina in AD 622.

Tabular Islamic calendar

Main article: Tabular Islamic calendar

The Tabular Islamic calendar is a rule-based variation of the Islamic calendar, in which months are worked out by arithmetic rules rather than by observation or astronomical calculation. It has a 30-year cycle with 11 leap years of 355 days and 19 years of 354 days. In the long term, it is accurate to one day in about 2,500 years. It also deviates up to about one or two days in the short term.

Kuwaiti algorithm

Main article: Tabular Islamic calendar § Kuwaiti algorithm

Microsoft uses the "Kuwaiti algorithm", a variant of the tabular Islamic calendar, to convert Gregorian dates to the Islamic ones. Microsoft claimed that the variant is based on a statistical analysis of historical data from Kuwait, however it matches a known tabular calendar.

Notable dates

Main article: Muslim holidays

Important dates in the Islamic (Hijri) year are:

• 1 Muharram (Islamic New Year)
• 10 Muharram (Day of Ashura) For Sunnis, the crossing of the Red Sea by Moses occurred on this day. For both Shias and Sunnis, the martyrdom of Husayn ibn Ali, the grandson of Muhammad, and his followers.
• 12 Rabi al Awal (Birth of Prophet Muhammad)
• 17 Rabi al Awal (Mawlid an Nabi for Twelvers)
• 27 Rajab (Isra and Mi'raj for majority of Muslims)
• 15 Sha'ban (Mid-Sha'ban, or Night of Forgiveness), and for Twelvers the birthday of Muhammad al-Mahdi (The Twelfth Imam)
• 1 Ramadan (First day of fasting)
• 23 Ramadan (Nuzul Al-Qur'an) The most probable day Muhammad received the first verses of the Qur'an. (17 Ramadan in Indonesia and Malaysia)
• Last third of Ramadan which includes Laylat al-Qadr
• 1 Shawwal (Eid ul-Fitr)
• 8–13 Dhu al-Hijjah (the Hajj to Mecca)
• 9 Dhu al-Hijjah (Day of Arafa)
• 10 Dhu al-Hijjah (Eid al-Adha)

Days considered important predominantly for Shia Muslims:

• 13 Rajab Birthday of Amir al Muminin Ali Ibn Abi Talib
• 21 Ramadan Imam Ali ibn Abi Talib's martyrdom.
• 3 Sha'ban (Birthday of Husayn ibn Ali).
• 9 Rabi ul Awal Eid-e-Zahra s.a (Revenge taken by Mukhtar-al-Saqafi)

Days considered important predominantly for Sunni Muslims (especially in India & parts of Asia):

• 6 Rajab Urs of Khwaja Moinuddin Chisti.(Generally 6th Day of Every Month is celebrated and observed as Chatthi)
• 11 Rabi Ul Aakhir Urs of Gaus E Aazam Dastagir (Generally 11th Day of Every Month is celebrated and observed as Gyarvi)

Converting Hijri to Gregorian date or vice versa

Civil and Hijri establishment dates of a library in Old City, Jerusalem

Conversions may be made online (see list below), by using the Tabular Islamic calendar (see Tabular Islamic calendar), or, for greatest accuracy (one day in 15,186 years), via the Jewish calendar. Theoretically, the days of the months correspond in both calendars if the displacements which are a feature of the Jewish system are ignored. The table below gives, for nineteen years, the Muslim month which corresponds to the first Jewish month.

Year AD Year AH Muslim month 2011 1432 5 2012 1433 5 2013 1434 5 2014 1435 6 2015 1436 6 2016 1437 7 2017 1438 7 2018 1439 7 2019 1440 8 2020 1441 8

Year AD Year AH Muslim month 2021 1442 8 2022 1443 9 2023 1444 9 2024 1445 10 2025 1446 10 2026 1447 10 2027 1448 11 2028 1449 11 2029 1450 11

This table may be extended since every nineteen years the Muslim month number increases by seven. When it goes above twelve, subtract twelve and add one to the year AH. From AD412 to AD632 inclusive the month number is 1 and the calculation gives the month correct to a month or so. AD622 corresponds to BH1 and AH1. For earlier years, year BH = (623 or 622) – year AD).

An example calculation: What is the civil date and year AH of the first day of the first month in the year AD 20875?

We first find the Muslim month number corresponding to the first month of the Jewish year which begins in AD20874. Dividing 20874 by 19 gives quotient 1098 and remainder 12. Dividing 2026 by 19 gives quotient 106 and remainder 12. The two years are therefore (1098–106)=992x19 years apart. The Muslim month number corresponding to the first Jewish month is therefore (992x7)=6944 higher than in 2026. To convert into years and months divide by twelve – 6944/12=578 years and 8 months. Adding, we get 1447y 10m + 20874y – 2026y + 578y 8m = 20874y 6m. Therefore, the first month of the Jewish year beginning in AD20874 corresponds to the sixth month of the Muslim year AH20874. The worked example in Conversion between Jewish and civil dates, shows that the civil date of the first day of this month (ignoring the displacements) is Friday, 14 June. The year AH20875 will therefore begin seven months later, on the first day of the eighth Jewish month, which the worked example shows to be 7 January, AD20875 (again ignoring the displacements). The date given by this method, being calculated, may differ by a day from the actual date, which is determined by observation.

A reading of the section which follows will show that the year AH20875 is wholly contained within the year AD20875, also that in the Gregorian calendar this correspondence will occur one year earlier. The reason for the discrepancy is that the Gregorian year (like the Julian) is slightly too long, so the Gregorian date for a given AH date will be earlier and the Muslim calendar catches up sooner.

Current correlations

An Islamic year will be entirely within a Gregorian year of the same number in the year 20874, after which year the number of the Islamic year will always be greater than the number of the concurrent civil year. The Islamic calendar year of 1429 occurred entirely within the civil calendar year of 2008. Such years occur once every 33 or 34 Islamic years (32 or 33 civil years). More are listed here:

Islamic year within civil year
Islamic	Civil	Difference
1060	1650	590
1093	1682	589
1127	1715	588
1161	1748	587
1194	1780	586
1228	1813	585
1261	1845	584
1295	1878	583
1329	1911	582
1362	1943	581
1396	1976	580
1429	2008	579
1463	2041	578
1496	2073	577
1530	2106	576
1564	2139	575

Because a hijri or Islamic lunar year is between 10 and 12 days shorter than a civil year, it begins 10–12 days earlier in the civil year following the civil year in which the previous hijri year began. Once every 33 or 34 hijri years, or once every 32 or 33 civil years, the beginning of a hijri year (1 Muharram) coincides with one of the first ten days of January. Subsequent hijri New Years move backward through the civil year back to the beginning of January again, passing through each civil month from December to January.

Uses

The Islamic calendar is now used primarily for religious purposes, and for official dating of public events and documents in Muslim countries. Because of its nature as a purely lunar calendar, it cannot be used for agricultural purposes and historically Islamic communities have used other calendars for this purpose: the Egyptian calendar was formerly widespread in Islamic countries, and the Iranian calendar and the 1789 Ottoman calendar (a modified Julian calendar) were also used for agriculture in their countries. In the Levant and Iraq the Aramaic names of the Babylonian calendar are still used for all secular matters. In Morocco, the Berber calendar (another Julian calendar) is still used by farmers in the countryside. These local solar calendars have receded in importance with the near-universal adoption of the Gregorian calendar for civil purposes. As noted above, Saudi Arabia uses the Islamic calendar to date religious occasions such as Ramadan, Hajj, etc. and the Umm-al-Qura calendar, based on calculations, for administrative purposes and daily government business. In Indonesia, the Javanese calendar, created by Sultan Agung in 1633, combines elements of the Islamic and pre-Islamic Saka calendars.

British author Nicholas Hagger writes that after seizing control of Libya, Muammar Gaddafi "declared" on 1 December 1978 "that the Muslim calendar should start with the death of the prophet Mohammed in 632 rather than the hijra (Mohammed's 'emigration' from Mecca to Medina) in 622". This put the country ten solar years behind the standard Muslim calendar. However, according to the 2006 Encyclopedia of the Developing World, "More confusing still is Qaddafi's unique Libyan calendar, which counts the years from the Prophet's birth, or sometimes from his death. The months July and August, named after Julius and Augustus Caesar, are now Nasser and Hannibal respectively." Reflecting on a 2001 visit to the country, American reporter Neil MacFarquhar observed, "Life in Libya was so unpredictable that people weren't even sure what year it was. The year of my visit was officially 1369. But just two years earlier Libyans had been living through 1429. No one could quite name for me the day the count changed, especially since both remained in play. ... Event organizers threw up their hands and put the Western year in parentheses somewhere in their announcements."

Computer Support

Since the release of Java 8, the Islamic calendar is supported in the new Date and Time API.

See also

• Islamic and Jahili months

External links

•  
• Helmer Aslaksen The Islamic Calendar
• Khalid Chraibi, The reform of the Islamic calendar: the terms of the debate, Tabsir.net, September 2012

Calendar-date converters

• URDU CALENDAR - Hijri, Islamic Gregorian Calendar
• Calendar Converter (based on the tabular Islamic calendar)
• The Umm Al-Qura (Mecca) Calendar (in Arabic, English explanation here)
• The Umm al-Qura Calendar of Saudi Arabia (with date converter valid from 1937 to 2077)
• The Islamic Calendar/Hijri Calendar for Makkah
• Online Alavi Taiyebi Calendar
• Islamic / Western Calendar Converter (supports all known variants of the tabular Islamic calendar)
• Hijri Date Converter