Hijri year#Formula

The Hijri year ({{langx|ar|سنة هجرية|sanat hijriyya}}) or era ({{langx|ar|التقويم الهجري|at-taqwīm al-hijrī|link=none}}) is the era used in the Islamic lunar calendar. It begins its count from the Islamic New Year in which Muhammad and his followers migrated from Mecca to Yathrib (now Medina) in 622 CE. This event, known as the Hijrah, is commemorated in Islam for its role in the founding of the first Muslim community (ummah). Currently, the Hijri year is {{nowrap|AH 1447}}{{dubious|The "Infobox calendar date today" here-above indicates 1446, not 1447. Which one shall I trust?|date=June 2025}}.{{update after|2025|05|26}} Please note: the lunar Hijri date, calculated according to the lunar Hijri calendar, is different from the solar Hijri date, calculated according to the solar Hijri calendar or Persian calendar, which is only being officially used in Iran ("Persia").

In the West, the lunar Hijri era is most commonly denoted as AH ({{langx|la|Anno Hegirae}}, {{IPAc-en|ˈ|æ|n|oʊ|_|ˈ|h|ɛ|dʒ|ᵻ|r|iː}}, {{lit|in the year of the Hijra}}) in parallel with the Christian/Common (AD/CE) and Jewish eras (AM) and can similarly be placed before (preferably) or after the date. In predominantly Muslim countries, it is also commonly abbreviated H ("Hijra") from its Arabic abbreviation {{Transliteration|ar|hāʾ}} ({{lang|ar|{{linktext|هـ}}}}). Years prior to AH 1 are reckoned in English as BH ("Before the Hijra"), which should follow the date.{{Citation |title=Registration locations |url=http://www.sharjah.ae/registration-locations.aspx?Val=111 |archive-url=https://web.archive.org/web/20170202005514/http://www.sharjah.ae/registration-locations.aspx?Val=111 |publisher=Government of Sharjah |access-date=21 January 2017 |archive-date=2 February 2017 |url-status=dead}}.

A year in the Islamic lunar calendar consists of twelve lunar months and has only 354 or 355 days in its year. Consequently, its New Year's Day occurs ten days earlier each year relative to the Gregorian calendar. The year {{CURRENTYEAR}} CE corresponds to the Islamic years AH{{nbsp}}{{#expr: floor( {{CURRENTYEAR}} - 622 + ({{CURRENTYEAR}} - 622) / 32) }} – {{#expr: floor( {{CURRENTYEAR}} - 622 + ({{CURRENTYEAR}} - 622) / 32)+1 }}; AH{{nbsp}}1446 corresponds to 2024{{snd}}2025 in the Common Era.{{efn|See List of Islamic years#Modern.}}{{update after|2025|06|26}}

Definition

The Hijri era is calculated according to the Islamic lunar calendar, whose epoch (first year) is the year of Muhammad's Hijrah, and begins on the first day of the month of Muharram (equivalent to the Julian calendar date of July 16, 622 CE).{{cite web |last1=Thomann |first1=Johannes |title=Islamischer Kalender |url=https://www.aoi.uzh.ch/de/islamwissenschaft/hilfsmittel/tools/kalenderumrechnung/hegira.html |website=Universität Zurich Universität Zürich Asien-Orient-Institut |access-date=11 April 2023 |archive-date=10 June 2023 |archive-url=https://web.archive.org/web/20230610113256/https://www.aoi.uzh.ch/de/islamwissenschaft/hilfsmittel/tools/kalenderumrechnung/hegira.html |url-status=live }}{{efn|This date is based on a reconstruction of the early Islamic calendar and, assuming that intercalation was performed before 10 AH, an earlier date in April is also possible.}}

The date of the Hijrah itself did not form the Islamic New Year. Instead, the system continues the earlier ordering of the months, with the Hijrah occurring around the 8th day of Rabi al-Awwal, 66 days into the first year.

= Shia view =

Unlike Sunnis, Twelver Shias start the Hijri year with the month of the Hijra, Rabi' al-Awwal, rejecting that Muharram is the start of a new year. As a result of this, the dates of some events are described differently by one year. For example, Shias state that the Muharram-transpiring battle of Karbala occurred 60 years after the Hijra, while Sunnis state it to have occurred 61 years after.{{Cite journal |last=Rizvi |first=Sa'eed Akhtar |author-link=Sa'id Akhtar Rizvi |date=1401 |title=Martyrdom of Imam Husayn and the Muslim and Jewish Calendars |url=https://www.al-islam.org/al-serat/vol-6-no-3-4-1401ah/martyrdom-imam-husayn-and-muslim-and-jewish-calendars-sayyid-saeed-0 |journal=Al-Serat (A Journal of Islamic Studies) |volume=6 |issue=3–4 |access-date=13 April 2024 |via=Ahlul Bayt Digital Islamic Library Project}}{{Cite web |last=Al-Hilli |first=Mohammed |date=22 September 2021 |title=Muharram May Not Be The Start Of The Islamic Hijri New Year |url=https://www.al-islam.org/media/muharram-may-not-be-start-islamic-hijri-new-year |access-date=13 April 2024 |website=Ahlul Bayt Digital Islamic Library Project}}

In Shia Islam, the calendar year is entirely determined by solar observation or calculation. Each year begins on the northward equinox.

History

=Predecessors=

By the age of Muhammad, there was already an Arabian lunar calendar, with named months. Likewise, the years of its calendar used conventional names rather than numbers: for example, the year of the birth of Muhammad and of Ammar ibn Yasir (570 CE) was known as the "Year of the Elephant".Hajjah Adil, Amina, "Prophet Muhammad", ISCA, Jun 1, 2002, {{ISBN|1-930409-11-7}} The first year of the Hijra (622–23 CE) was named the "Permission to Travel" in this calendar.

=Establishment=

17 years after the Hijra,{{Cite web |last=Aisha El-Awady |date=2002-06-11 |title=Ramadan and the Lunar Calendar |url=http://www.islamonline.net/English/Science/2002/11/article02.shtml |access-date=2006-12-16 |publisher=Islamonline.net |archive-date=2006-12-14 |archive-url=https://web.archive.org/web/20061214114419/http://www.islamonline.net/English/Science/2002/11/article02.shtml |url-status=live }}{{Cite web |last=Hakim Muhammad Said |year=1981 |title=The History of the Islamic Calendar in the Light of the Hijra |url=http://al-islam.org/al-serat/hijrah.htm |access-date=2006-12-16 |website=Ahlul Bayt Digital Islamic Library Project |archive-date=2011-06-10 |archive-url=https://web.archive.org/web/20110610073112/http://www.al-islam.org/al-serat/hijrah.htm |url-status=live }} a complaint from Abu Musa Ashaari prompted the caliph Umar to abolish the practice of named years and to establish a new calendar era. Umar chose as epoch for the new Muslim calendar the hijrah, the emigration of Muhammad and 70 Muslims from Mecca to Medina.[https://www.soundvision.com/article/the-beginning-of-hijri-calendar The Beginning of Hijri calendar] {{Webarchive|url=https://web.archive.org/web/20190101193832/https://www.soundvision.com/article/the-beginning-of-hijri-calendar |date=2019-01-01 }}{{snd}} Paul Lunde, Saudi Aramco World Magazine (November/December 2005), retrieved 1/1/2019 Tradition credits Othman with the successful proposal, simply continuing the order of the months that had already been established by Muhammad, beginning with Muharram,{{citation needed|date=September 2015}} as there was no set order of months during the pre-Islamic era (Age of Ignorance – Jahiliya). Adoption of this calendar was then enforced by Umar.{{Cite web |last=Umar bin Al-Khattab |year=2002 |title=Islamic Actions and Social Mandates: The Hijri Calendar |url=http://www.witness-pioneer.org/vil/Articles/companion/14_umar_bin_al_khattab.htm#The%20Hijri%20Calendar |access-date=2006-12-16 |publisher=witness-pioneer.org |archive-date=2018-08-19 |archive-url=https://web.archive.org/web/20180819150223/http://www.witness-pioneer.org/vil/Articles/companion/14_umar_bin_al_khattab.htm#The%20Hijri%20Calendar |url-status=live }}

Formula

Different approximate conversion formulas between the Gregorian (AD or CE) and Islamic calendars (AH) are possible:{{Cite web |url=http://www.classicalislam.com/pages/history/dating.htm |title=Islamic and Christian Dating Systems |access-date=2015-10-11 |archive-date=2017-02-03 |archive-url=https://web.archive.org/web/20170203035519/http://www.classicalislam.com/pages/history/dating.htm |url-status=live }}{{Cite book |last=Clark |first=Malcolm |url=https://books.google.com/books?id=zPXu561ZpvgC&pg=PT489 |title=Islam for dummies |date=2013 |publisher=John Wiley & Sons |isbn=978-1118053966 |location=Hoboken, N.J. |page=489}}{{Cite book |last=Hodgson |first=Marshall G. S. |url=https://books.google.com/books?id=18b-K9AMLlwC&pg=PA21 |title=The venture of Islam conscience and history in a world civilization |date=1977 |publisher=University of Chicago Press |isbn=0226346862 |location=Chicago |page=21}}

AH = 1.030684 × (CE − 621.5643)

CE = 0.970229 × AH + 621.5643

AH = (CE − 622) × {{frac|33|32}}

CE = AH × {{frac|32|33}} + 622

Given that the Islamic New Year does not begin January 1 and that a Hijri calendar year is about 11 days shorter than a Gregorian calendar year,{{cite EB1911 |wstitle=Hejira |volume=13 |page=218}}{{efn|As the mean duration of a tropical year is 365.24219 days, while the long-term average duration of a lunar year is 354.36707 days,{{cite book | title=Explanatory Supplement to the Astronomical Almanac |year=1992 | editor=P. Kenneth Seidelmann |page=577 |url=https://archive.org/details/131123ExplanatorySupplementAstronomicalAlmanac/page/n302/mode/1up | quote=For convenience, it is common to speak of a lunar year of twelve synodic months, or 354.36707 days.}} (which gives a mean synodic month as 29.53059 days or 29 days 12 hours 44 minutes and 3 seconds) the average lunar year is (365.24219 − 354.36707 ≈) 10.88149 days shorter than the average solar year, causing months of the Hijri calendar to advance about eleven days earlier relative to dates in the Gregorian calendar every calendar year. The precise number of days varies, depending on accumulated differences and potential for leap-years to happen at different times. }} there is no direct correspondence between years of the two eras. A given Hijri year will usually fall in two successive Gregorian years. A CE year will always overlap two or occasionally three successive Hijri years. For example, the year 2008 CE maps to the last week of AH 1428,{{Cite news |date=January 20, 2007 |title=Islamic New Year Observed Today; President Airs Wish for Peace on Amon Jadid Exhorts Muslims to Assist in Nat'l Resurgence |work=Manila Bulletin |publisher=|url=https://www.questia.com/library/1G1-157963129/islamic-new-year-observed-today-president-airs-wish |access-date=}}{{dead link|date=July 2021}} all of 1429,{{Cite web |date=2008-01-10 |title=Islamic New year to be observed on 11th January |url=http://www.aaj.tv/2008/01/islamic-new-year-to-be-observed-on-11th-january/ |access-date=2013-05-22 |website=AAJ News |publisher=Aaj.tv |archive-date=2018-12-22 |archive-url=https://web.archive.org/web/20181222034225/http://www.aaj.tv/2008/01/islamic-new-year-to-be-observed-on-11th-january/ |url-status=dead }} and the first few days of 1430.{{Cite web |title=Visibility of Muharram Crescent 1430 AH |url=http://www.icoproject.org/icop/muh30.html |website=Islamic Crescents' Observation Project |access-date=2018-12-21 |archive-date=2021-02-23 |archive-url=https://web.archive.org/web/20210223233155/http://www.icoproject.org/icop/muh30.html |url-status=dead }} Similarly, the year 1976 CE corresponded with the last few days of AH 1395, all of 1396, and the first week of 1397.

Months

The Hijri year has twelve months, whose precise lengths vary by sect of Islam. Each month of the Islamic calendar commences on the birth of the new lunar cycle. Traditionally this is based on actual observation of the moon's crescent ({{Transliteration|ar|hilal}}) 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 Bohras Muslims namely Alavis, Dawoodis and Sulaymanis and Shia Ismaili Muslims, use a tabular Islamic calendar in which odd-numbered months have thirty days (and also the twelfth month in a leap year) and even months have twenty nine.

Hijri year#Formula

Definition

= Shia view =

History

=Predecessors=

=Establishment=

Formula

Months

See also

Notes

References

Further reading