Gregorian calendar

2018 in various calendars
Gregorian calendar2018
Ab urbe condita2771
Armenian calendar1467
Assyrian calendar6768
Bahá'í calendar174–175
Balinese saka calendar1939–1940
Bengali calendar1425
Berber calendar2968
British Regnal year66 Eliz. 2 – 67 Eliz. 2
Buddhist calendar2562
Burmese calendar1380
Byzantine calendar7526–7527
Chinese calendar丁酉(Fire Rooster)
4714 or 4654
    — to —
戊戌年 (Earth Dog)
4715 or 4655
Coptic calendar1734–1735
Discordian calendar3184
Ethiopian calendar2010–2011
Hebrew calendar5778–5779
Hindu calendars
 - Vikram Samvat2074–2075
 - Shaka Samvat1939–1940
 - Kali Yuga5118–5119
Holocene calendar12018
Igbo calendar1018–1019
Iranian calendar1396–1397
Islamic calendar1439–1440
Japanese calendarHeisei 30
Javanese calendar1951–1952
Juche calendar107
Julian calendarGregorian minus 13 days
Korean calendar4351
Minguo calendarROC 107
Nanakshahi calendar550
Thai solar calendar2561
Tibetan calendar阴火鸡年
(female Fire-Rooster)
2144 or 1763 or 991
    — to —
(male Earth-Dog)
2145 or 1764 or 992
Unix time1514764800 – 1546300799

The Gregorian calendar is the most widely used civil calendar in the world.[1][2][Note 1] It is named after Pope Gregory XIII, who introduced it in October 1582. The calendar spaces leap years to make the average year 365.2425 days long, approximating the 365.2422 day tropical year that is determined by the Earth's rotation around the Sun. The rule for leap years is as follows:

Every year that is exactly divisible by four is a leap year, except for years that are exactly divisible by 100, but these centurial years are leap years if they are exactly divisible by 400. For example, the years 1700, 1800, and 1900 are not leap years, but the year 2000 is.[3]

The calendar was developed as a refinement of the Julian calendar,[4] shortening the average year by 0.0075 days to stop the drift of the calendar with respect to the equinoxes. To deal with the 10 days of accumulated drift, the date was advanced so that 4 October 1582 was followed by 15 October 1582. There was no discontinuity in the cycle of weekdays or of the Anno Domini calendar era.[Note 2] The reform also altered the lunar cycle used by the Church to calculate the date for Easter, restoring it to the time of the year as originally celebrated by the early Church.

The reform was adopted initially by the Catholic countries of Europe. Over the next three centuries, the Protestant and Eastern Orthodox countries also moved to what they called the Improved calendar, with Greece being the last European country to adopt the calendar in 1923.[6] To unambiguously specify a date during the transition period, dual dating is sometimes used to specify both Old Style and New Style dates. Due to globalization in the 20th century, the calendar has also been adopted by most non-European countries for civil purposes. The calendar era carries the secular name of the Common Era.[Note 3]


A year is divided into twelve months
No. Name Length in days
1 January 31
2 February 28 (29 in leap years)
3 March 31
4 April 30
5 May 31
6 June 30
7 July 31
8 August 31
9 September 30
10 October 31
11 November 30
12 December 31

The Gregorian calendar is a solar calendar with 12 months of 28–31 days each. A regular Gregorian year consists of 365 days, but in certain years known as leap years, a leap day is added to February. Gregorian years are identified by consecutive year numbers.[7] A calendar date is fully specified by the year (numbered according to a calendar era), the month (identified by name or number), and the day of the month (numbered sequentially starting from 1). Although the calendar year currently runs from 1 January to 31 December, at previous times year numbers were based on a different starting point within the calendar (see the "beginning of the year" section below).

In the Julian calendar, a leap year occurred every 4 years, and the leap day was inserted by doubling 24 February. The Gregorian reform omitted a leap day in three of every 400 years and left the leap day unchanged. However, it has become customary in the modern period to number the days sequentially with no gaps, and 29 February is typically considered as the leap day. Before the 1969 revision of the Roman Calendar, the Roman Catholic Church delayed February feasts after the 23rd by one day in leap years; Masses celebrated according to the previous calendar still reflect this delay.[8]

Calendar cycles repeat completely every 400 years, which equals 146,097 days.[Note 4][Note 5] Of these 400 years, 303 are regular years of 365 days and 97 are leap years of 366 days. A mean calendar year is 365 97/400 days = 365.2425 days, or 365 days, 5 hours, 49 minutes and 12 seconds.[Note 6]

Other Languages
العربية: تقويم ميلادي
azərbaycanca: Qriqori təqvimi
Bahasa Banjar: Almanak Gregorius
Bân-lâm-gú: Gregorius Le̍k-hoat
Basa Banyumasan: Kalendher Gregorian
беларуская (тарашкевіца)‎: Грыгарыянскі каляндар
Chavacano de Zamboanga: Calendario Gregoriano
ދިވެހިބަސް: މީލާދީ ކަލަންޑަރު
dolnoserbski: Gregorjaniska pratyja
emiliàn e rumagnòl: Lunâri Gregoriân
客家語/Hak-kâ-ngî: Gregorius La̍k-fap
한국어: 그레고리력
hornjoserbsce: Gregorianiska protyka
বিষ্ণুপ্রিয়া মণিপুরী: গ্রেগরিয়ান পাঞ্জী
Bahasa Indonesia: Kalender Gregorius
къарачай-малкъар: Григориан орузлама
kernowek: Calans gregorek
Kreyòl ayisyen: Almanak gregoryen
Lëtzebuergesch: Gregorianesche Kalenner
مازِرونی: میلادی تقویم
Bahasa Melayu: Takwim Gregorius
Mìng-dĕ̤ng-ngṳ̄: Gregorius Lĭk-huák
Nedersaksies: Gregoriaanse kalender
oʻzbekcha/ўзбекча: Grigoriy taqvimi
Plattdüütsch: Gregoriaansch Klenner
Gagana Samoa: Kalena Kurekoria
Sesotho sa Leboa: Tšhupamabaka ya Gregorian
Simple English: Gregorian calendar
slovenščina: Gregorijanski koledar
srpskohrvatski / српскохрватски: Gregorijanski kalendar
Basa Sunda: Kalénder Grégori
татарча/tatarça: Милади тәкъвим
Türkçe: Miladi takvim
Tiếng Việt: Lịch Gregorius
文言: 格里曆
吴语: 公曆
粵語: 公曆
中文: 格里曆