Chinese Calendar

The traditional Chinese calendar, dating back to the Han dynasty, is a lunisolar calendar that blends solar, lunar, and other cycles for social and agricultural purposes. While modern China primarily uses the Gregorian calendar for official purposes, the traditional calendar remains culturally significant. It determines the timing of Chinese New Year with traditions like the twelve animals of the Chinese Zodiac still widely observed.

The traditional Chinese calendar uses the sexagenary cycle, a repeating system of Heavenly Stems and Earthly Branches, to mark years, months, and days. This system, along with astronomical observations and mathematical calculations, was developed to align solar and lunar cycles, though some approximations are necessary due to the natural differences between these cycles. Over centuries, the calendar was refined through advancements in astronomy and horology, with dynasties introducing variations to improve accuracy and meet cultural or political needs.

While the Gregorian calendar has become now standard for civic daily use in China, the traditional lunisolar calendar continues to influence festivals, cultural practices, and zodiac-based customs. Beyond China, it has shaped other East Asian calendars, including the Korean, Vietnamese, and Japanese lunisolar systems, each adapting the same lunisolar principles while integrating local customs and terminology.

Epochs, or fixed starting points for year counting, have played an essential role in the Chinese calendar's structure. Some epochs are based on historical figures, such as the inauguration of the Yellow Emperor ( Huangdi), while others marked the rise of dynasties or significant political shifts. This system allowed for the numbering of years based on regnal eras, with the start of a ruler's reign often resetting the count.

The Chinese calendar also tracks time in smaller units, including months, days, and double-hour periods called shichen. These timekeeping methods have influenced broader fields of horology, with some principles, such as precise time subdivisions, still evident in modern scientific timekeeping. The continued use of the calendar today highlights its enduring cultural, historical, and scientific significance.

Etymology

The name of calendar is in zh, c=曆, p=lì, and was represented in earlier character forms variants (), and ultimately derived from an ancient form (). The ancient form of the character consists of two stalks of rice plant (), arranged in parallel. This character represents the order in space and also the order in time. As its meaning became complex, the modern dedicated character () was created to represent the meaning of calendar.

Maintaining the correctness of calendars was an important task to maintain the authority of rulers, being perceived as a way to measure the ability of a ruler. For example, someone seen as a competent ruler would foresee the coming of seasons and prepare accordingly. This understanding was also relevant in predicting abnormalities of the Earth and celestial bodies, such as lunar and solar eclipses. The significant relationship between authority and timekeeping helps to explain why there are 102 calendars in Chinese history, trying to predict the correct courses of sun, moon and stars, and marking good time and bad time. Each calendar is named as and recorded in a dedicated calendar section in history books of different eras. The last one in imperial era was . A ruler would issue an almanac before the commencement of each year. There were private almanac issuers, usually illegal, when a ruler lost his control of some territories.

There are various Chinese terms for the calendar including:

* Nongli Calendar ( zh, links=yes, t=農曆, s=农历, p=nónglì, l=agricultural calendar)
* Jiuli Calendar ( zh, links=yes, t=舊曆, s=旧历, p=jiùlì, j=Gau6 Lik6, l=former calendar)
* Laoli Calendar ( zh, links=yes, t=老曆, s=老历, p=lǎolì, l=old calendar)
* Zhongli Calendar ( zh, links=yes, t=中曆, s=中历, p=zhōnglì, j=zung1 lik6, l=Chinese calendar)
* Huali Calendar ( zh, links=yes, t=華曆, s=华历, p=huálì, j=waa4 lik6, l=Chinese calendar)

Various modern Chinese calendar names resulted from the struggle between the introduction of Gregorian calendar by government and the preservation of customs by the public in the era of Republic of China. The government wanted to abolish the Chinese calendar to force everyone to use the Gregorian calendar, and even abolished the Chinese New Year, but faced great opposition. The public needed the astronomical Chinese calendar to do things at a proper time, for example farming and fishing; also, a wide spectrum of festivals and customs observations have been based on the calendar. The government finally compromised and rebranded it as the agricultural calendar in 1947, depreciating the calendar to merely agricultural use.

After the end of the imperial era, there are some almanacs based upon the algorithm of the last Imperial calendar with longitude of Peking. Such almanacs were under the name of "universal book" , or under Cantonese name , transcribed as Tung Shing. Later these almanacs moved to new calculation based on the location of Purple Mountain Observatory, with longitude of 120°E.

Year-numbering systems

Eras

Ancient China numbered years from an emperor's ascension to the throne or his declaration of a new era name. The first recorded reign title was , from 140 BCE; the last reign title was zh, labels=no, s=宣统, t=宣統, l=, c=, p=Xuāntǒng, out=p, from 1908 CE. The era system was abolished in 1912, after which the current or Republican era was used.

Epochs

An epoch is a point in time chosen as the origin of a particular calendar era, thus serving as a reference point from which subsequent time or dates are measured. The use of epochs in Chinese calendar system allow for a chronological starting point from whence to begin point continuously numbering subsequent dates. Various epochs have been used. Similarly, nomenclature similar to that of the Christian era has occasionally been used:

No reference date is universally accepted. The most popular is the Gregorian calendar ( zh, labels=no, p=gōnglì, t=, s=, l=common calendar).

During the 17th century, the Jesuit missionaries tried to determine the epochal year of the Chinese calendar. In his (published in Munich in 1658), Martino Martini (1614–1661) dated the Yellow Emperor's ascension at 2697 BCE and began the Chinese calendar with the reign of Fuxi (which, according to Martini, began in 2952 BCE).
Philippe Couplet's 1686 ''Chronological table of Chinese monarchs'' () gave the same date for the Yellow Emperor. The Jesuits' dates provoked interest in Europe, where they were used for comparison with Biblical chronology. Modern Chinese chronology has generally accepted Martini's dates, except that it usually places the reign of the Yellow Emperor at 2698 BCE and omits his predecessors Fuxi and Shennong as "too legendary to include".

Publications began using the estimated birth date of the Yellow Emperor as the first year of the Han calendar in 1903, with newspapers and magazines proposing different dates. Jiangsu province counted 1905 as the year 4396 (using a year 1 of 2491 BCE, and implying that CE is ), and the newspaper '' Ming Pao'' ( zh, labels=no, t=明報) reckoned 1905 as 4603 (using a year 1 of 2698 BCE, and implying that CE is ). Liu Shipei (, 1884–1919) created the Yellow Emperor Calendar (), with year 1 as the birth of the emperor (which he determined as 2711 BCE, implying that CE is ). There is no evidence that this calendar was used before the 20th century. Liu calculated that the 1900 international expedition sent by the Eight-Nation Alliance to suppress the Boxer Rebellion entered Beijing in the 4611th year of the Yellow Emperor.

Taoists later adopted Yellow Emperor Calendar and named it Tao Calendar ().

On 2 January 1912, Sun Yat-sen announced changes to the official calendar and era. 1 January was 14 4609 year, assuming a year 1 of 2698 BCE, making CE year . Many overseas Chinese communities like San Francisco's Chinatown adopted the change.

The modern Chinese standard calendar uses the epoch of the Gregorian calendar, which is on 1 January of the year 1 CE.

History

The Chinese calendar system has a long history, which has traditionally been associated with specific dynastic periods. Various individual calendar types have been developed with different names. In terms of historical development, some of the calendar variations are associated with dynastic changes along a spectrum beginning with a prehistorical/mythological time to and through well attested historical dynastic periods. Many individuals have been associated with the development of the Chinese calendar, including researchers into underlying astronomy; and, furthermore, the development of instruments of observation are historically important. Influences from India, Islam, and Jesuits also became significant.

Solar calendars

The traditional Chinese lunisolar calendar was developed between 771 BCE and 476 BCE, during the Spring and Autumn period of the Eastern Zhou dynasty. Solar calendars were used before the Zhou dynasty period, along with the basic sexagenary system.

One version of the solar calendar is the five-elements (or phases) calendar (), which derives from the Wu Xing. A 365-day year was divided into five phases of 72 days, with each phase preceded by an intercalary day associated with the claimed beginning of the following 72 day period of domination by the next Wu Xing element; thus, the five phases each begin with a governing-element day (), followed by a 72-day period characterized by the ruling element. Years began on a day and a 72-day wood phase, followed by a day and a 72-day fire phase; a day and a 72-day earth phase; a day and a 72-day metal phase, and a day followed by a water phase. Each phase consisted of two three-week months, making each year ten months long. Other days were tracked using the Yellow River Map (''He Tu'').

Another version is a four-quarters calendar ( zh, labels=no, s=四时八节历, t=四時八節曆, l=four seasons eight solar terms calendar, p=sìshí bājié lì, or zh, labels=no, t=四分曆, s=四分历, p=sìfēn lì, l=quarters calendar). The weeks were ten days long, with one month consisting of three weeks. A year had 12 months, with a ten-day week intercalated in summer as needed to keep up with the tropical year. The 10 Heavenly Stems and 12 Earthly Branches were used to mark days.

A third version is the balanced calendar ( zh, labels=no, t=調曆, s=调历 , p=tiáo lì). A year was 365.25 days, and a month was 29.5 days. After every 16th month, a half-month was intercalated. According to oracle bone records, the Shang dynasty calendar ( BCE) was a balanced calendar with 12 to 14 months in a year; the month after the winter solstice was .

A solar calendar called the Tung Shing, the ''Yellow Calendar'' or ''Imperial Calendar'' (both alluding to Yellow Emperor) continued to see use as an almanac and agricultural guide throughout Chinese history.

Lunisolar calendars by dynasty

Lunisolar calendars involve correlations of the cycles of the sun (solar) and the moon (lunar).

Zhou dynasty

The first lunisolar calendar was the ''Zhou'' calendar ( zh, labels=no, t=周曆, s=周历), introduced under the Zhou dynasty (1046 BCE – 256 BCE). This calendar sets the beginning of the year at the day of the new moon before the winter solstice.

Competing Warring states calendars

Several competing lunisolar calendars were introduced as Zhou devolved into the Warring States, especially by states fighting Zhou control during the Warring States period (perhaps 475 BCE - 221 BCE).
From the Warring States period (ending in 221 BCE), six especially significant calendar systems are known to have begun to be developed. Later on, during their future course in history, the modern names for the ancient six calendars were also developed: ''Huangdi, Yin, Zhou, Xia, Zhuanxu,'' and ''Lu''.

Modern historical knowledge and records are limited for the earlier calendars. These calendars are known as the ''six ancient calendars'' ( zh, labels=no, t=古六曆, s=古六历), or quarter-remainder calendars, ( zh, labels=no, t=四分曆, s=四分历, p=sìfēnlì), since all calculate a year as days long. Months begin on the day of the new moon, and a year has 12 or 13 months. Intercalary months (a 13th month) are added to the end of the year.

The state of Lu issued its own ''Lu calendar'' ( zh, labels=no, t=魯曆, s=鲁历).

The state of Jin issued the '' Xia calendar'' ( zh, labels=no, t=夏曆, s=夏历) with a year beginning on the day of the new moon nearest the March equinox.

The state of Qin issued the '' Zhuanxu calendar'' ( zh, labels=no, t=顓頊曆, s=颛顼历), with a year beginning on the day of the new moon nearest the winter solstice.

The ''Qiang'' and ''Dai calendars'' are modern versions of the Zhuanxu calendar, used by highland peoples.

The Song state's '' Yin calendar'' ( zh, labels=no, t=殷曆, s=殷历) began its year on the day of the new moon after the winter solstice.

Qin and early Han dynasties

After Qin Shi Huang unified China under the Qin dynasty in 221 BCE, the ''Qin calendar'' ( zh, labels=no, t=秦曆, s=秦历) was introduced.
It followed most of the rules governing the Zhuanxu calendar, but the month order was that of the Xia calendar; the year began with month 10 and ended with month 9, analogous to a Gregorian calendar beginning in October and ending in September. The intercalary month, known as ''the second'' zh, labels=no, t=後九月, s=后九月, p=Jiǔyuè, out=p, was placed at the end of the year. The Qin calendar was used going into the Han dynasty.

Han dynasty Tàichū calendar

Emperor Wu of Han introduced reforms in the seventh of the eleven named eras of his reign, zh, labels=no, t=太初, s=太初, p=Tàichū, l=Grand Beginning, out=p, 104 BCE – 101 BCE. His '' calendar'' ( zh, labels=no, t=太初曆, s=太初历, l=grand beginning calendar) defined a solar year as days (365;06:00:14.035), and the lunisolar month had days (29;12:44:44.444).
Since $\left(365+\frac\right)\times19=\left(29+\frac\right)\times \left(19\times 12 + 7 \right)$ the 19 years cycle used for the 7 additional months was taken as an exact one, and not as an approximation.

This calendar introduced the 24 solar terms, dividing the year into 24 equal parts of 15° each. Solar terms were paired, with the 12 combined periods known as ''climate terms''. The first solar term of the period was known as a pre-climate (), and the second was a mid-climate (). Months were named for the mid-climate to which they were closest, and a month without a mid-climate was an intercalary month.

The Taichu calendar established a framework for traditional calendars, with later calendars adding to the basic formula.

Northern and Southern Dynasties Dàmíng calendar

The ''Dàmíng calendar'' ( zh, labels=no, t=大明曆, s=大明历, l=brightest calendar), created in the Northern and Southern Dynasties by Zu Chongzhi (429 CE – 500 CE), introduced the equinoxes.

Tang dynasty Wùyín Yuán calendar

The use of syzygy to determine the lunisolar month was first described in the Tang dynasty '' calendar'' ( zh, labels=no, t=戊寅元曆, s=戊寅元历, l=earth tiger epoch calendar).

Yuan dynasty Shòushí calendar

The Yuan dynasty ''Shòushí calendar'' ( zh, labels=no, t=授時曆, s=授时历, l=season granting calendar) used spherical trigonometry to find the length of the tropical year.
The calendar had a 365.2425-day year, identical to the Gregorian calendar.

Ming and Qing Shíxiàn calendar

From 1645 to 1913 the ' or ''Chongzhen calendar'' was developed. During the late Ming dynasty, the Chinese Emperor appointed Xu Guangqi in 1629 to be the leader of the Shixian calendar reform. Assisted by Jesuits, he translated Western astronomical works and introduced new concepts, such as those of Nicolaus Copernicus, Johannes Kepler, Galileo Galilei, and Tycho Brahe; however, the new calendar was not released before the end of the dynasty.

In the early Qing dynasty, Johann Adam Schall von Bell submitted the calendar which was edited by the lead of Xu Guangqi to the Shunzhi Emperor.
The Qing government issued it as the '' (seasonal) calendar''. In this calendar, the solar terms are 15° each along the ecliptic and it can be used as a solar calendar. However, the length of the climate term near the perihelion is less than 30 days and there may be two mid-climate terms. The calendar changed the mid-climate-term rule to "decide the month in sequence, except the intercalary month."

The present "traditional calendar" follows the Shíxiàn calendar, except:
# The baseline is Chinese Standard Time, rather than Beijing local time.
# Modern astronomical data, rather than mathematical calculations, is used.

Modern Chinese calendar

The Chinese calendar lost its place as the country's official calendar at the beginning of the 20th century, its use has continued.

The ''Republic of China Calendar'' published by the Beiyang government of the Republic of China still listed the dates of the Chinese calendar in addition to the Gregorian calendar.

In 1929, the Nationalist government tried to ban the traditional Chinese calendar. The '' Calendar'' published by the government no longer listed the dates of the Chinese calendar.
However, Chinese people were used to the traditional calendar and many traditional customs were based on the Chinese calendar. The ban failed and was lifted in 1934.

The latest Chinese calendar was "New Edition of , revised edition", edited by Beijing Purple Mountain Observatory, People's Republic of China.

In China, the modern calendar is defined by the Chinese national standard GB/T 33661–2017, "Calculation and Promulgation of the Chinese Calendar", issued by the Standardization Administration of China on 12 May 2017.

Although modern-day China uses the Gregorian calendar, the traditional Chinese calendar governs holidays, such as the Chinese New Year and Lantern Festival, in both China and overseas Chinese communities. It also provides the traditional Chinese nomenclature of dates within a year which people use to select auspicious days for weddings, funerals, moving or starting a business. The evening state-run news program ''Xinwen Lianbo'' in the People's Republic of China continues to announce the months and dates in both the Gregorian and the traditional lunisolar calendar.

To optimize the Chinese calendar, astronomers have proposed a number of changes. Kao Ping-tse ( zh, labels=no, c=高平子; 1888–1970), a Chinese astronomer who co-founded the Purple Mountain Observatory, proposed that month numbers be calculated before the new moon and solar terms to be rounded to the day. Since the intercalary month is determined by the first month without a mid-climate and the mid-climate time varies by time zone, countries that adopted the calendar but calculate with their own time could vary from the time in China.

Contributions from Chinese astronomy

The Chinese calendar has been a development involving much observation and calculation of the apparent movements of the Sun, Moon, planets, and stars, as observed from Earth.

Many Chinese astronomers have contributed to the development of the Chinese calendar. Many were of the scholarly or ''shi'' class ( zh , t = 士, s =士, p=shì), including writers of history, such as Sima Qian.

Notable Chinese astronomers who have contributed to the development of the calendar include Gan De, Shi Shen, and Zu Chongzhi

Early technological developments aiding in calendar development include the development of the gnomon. Later technological developments useful to the calendar system include naming, numbering and mapping of the sky, the development of analog computational devices such as the armillary sphere and the water clock, and the establishment of observatories.

Phenology

Early calendar systems, including the Chinese calendar, often were closely tied to natural phenomena. Phenology is the study of periodic events in biological life cycles and how these are influenced by seasonal and interannual variations in climate, as well as habitat factors (such as elevation). The plum-rains season (), the rainy season in late spring and early summer, begins on the first day after '' Mangzhong'' () and ends on the first day after Xiaoshu (). The Three Fu ( zh, labels=no, c=, p=sānfú) are three periods of hot weather, counted from the first day after the summer solstice. The first ( zh, labels=no, c=初伏, p=chūfú) is 10 days long. The mid- ( zh, labels=no, c=中伏, p=zhōngfú) is 10 or 20 days long. The last ( zh, labels=no, c=末伏, p=mòfú) is 10 days from the first day after the beginning of autumn. The Shujiu cold days ( zh, labels=no, p=shǔjǐu, c=數九, l=counting to nine) are the 81 days after the winter solstice (divided into nine sets of nine days), and are considered the coldest days of the year. Each nine-day unit is known by its order in the set, followed by "nine" (). In traditional Chinese culture, "nine" represents the infinity, which is also the number of "Yang". According to one belief nine times accumulation of "Yang" gradually reduces the "Yin", and finally the weather becomes warm.

Names of months

Lunisolar months were originally named according to natural phenomena. Current naming conventions use numbers as the month names. Every month is also associated with one of the twelve Earthly Branches.
}. square of Pegasus month
, zh , c= , labels=no , p=yínyuè , l=tiger month
, zh , c= , labels=no , p=zhēngyuè , l=first month
, -
, 2
, between 20 February – 21 March *
, zh , c= , labels=no, l= apricot month , p=xìngyuè
, zh , c= , labels=no, l=rabbit month , p=mǎoyuè
, zh , c= , labels=no, l=second month , p=èryuè
, -
, 3
, between 21 March – 20 April *
, zh , c= , labels=no , p=táoyuè , l=peach month
, zh , c= , labels=no , p=chényuè , l=dragon month
, zh , c= , labels=no, p=sānyuè , l=third month
, -
, 4
, between 20 April – 21 May *
, zh , c= , labels=no , p=méiyuè , l=plum month
, zh , c= , labels=no , p=sìyuè , l=snake month
, zh , c= , labels=no, p=sìyuè , l=fourth month
, -
, 5
, between 21 May – 21 June *
, zh , c= , labels=no , p=liúyuè , l=pomegranate month
, zh , c= , labels=no , p=wǔyuè , l=horse month
, zh , c= , labels=no , p=wǔyuè , l=fifth month
, -
, 6
, between 21 June – 23 July *
, zh , c= , labels=no , l= lotus month , p=héyuè
, zh , c= , labels=no , l=goat month , p=wèiyuè
, zh , c= , labels=no , l=sixth month , p=liùyuè
, -
, 7
, between 23 July – 23 August *
, zh , t= , s= , labels=no , l=orchid month , p=lányuè
, zh , c= , labels=no , l=monkey month , p=shēnyuè
, zh , c= , labels=no , l=seventh month , p=qīyuè
, -
, 8
, between 23 August – 23 September *
, zh , c= , labels=no , l=osmanthus month , p=guìyuè
, zh , c= , labels=no , l=rooster month , p=yǒuyuè
, zh , c= , labels=no , l=eighth month , p=bāyuè
, -
, 9
, between 23 September – 23 October *
, zh , c= , labels=no , p=júyuè , l= chrysanthemum month
, zh , c= , labels=no , l=dog month , p=xūyuè
, zh , c= , labels=no , l=ninth month , p=jiǔyuè
, -
, 10
, between 23 October – 22 November *
, zh , c= , labels=no , p=lùyuè , l= dew month
, zh , c= , labels=no , l=pig month , p=hàiyuè
, zh , c= , labels=no , l=tenth month , p= shíyuè
, -
, 11
, between 22 November – 22 December *
, zh , c= , labels=no , p=dōngyuè , l=winter month; zh , c= , labels=no , p=jiāyuè , l= reed month
, zh , c= , labels=no , l=rat month , p=zǐyuè
, zh , c= , labels=no , l=eleventh month or zh , c= , labels=no , l=eleventh month , p=dōngyuè
, -
, 12
, between 22 December – 21 January *
, zh , c= , labels=no , p=bīngyuè , l=ice month
, zh , c= , labels=no , l=ox month , p=chǒuyuè
, zh , c= , labels=no , l=twelfth month or zh , s= , t= , labels=no , p=làyuè , l=end-of-year month

*Gregorian dates are approximate and should be used with caution. Many years have intercalary months.

Though the numbered month names are often used for the corresponding month number in the Gregorian calendar, it is important to realize that the numbered month names are not interchangeable with the Gregorian months when talking about Chinese calendar dates.

*''Incorrect'': The Dragon Boat Festival falls on 5 May in the traditional Chinese calendar, whereas the Double Ninth Festival, Lantern Festival, and Qixi Festival fall on 9 September, 15 January, and 7 July in the traditional Chinese calendar, respectively.
*''Correct'': The Dragon Boat Festival falls on 5th in the traditional Chinese calendar, whereas the Double Ninth Festival, Lantern Festival and Qixi Festival fall on 9th, 15th and 7th in the traditional Chinese calendar, respectively.
*''Alternate Chinese Zodiac correction'': The Dragon Boat Festival falls on Horse Month 5th in the traditional Chinese calendar, whereas the Double Ninth Festival, Lantern Festival and Qixi Festival fall on Dog Month 9th, Tiger Month 15th and Monkey Month 7th in the traditional Chinese calendar, respectively (see Sexagenary system below).

Horology

Horology, or chronometry, refers to the measurement of time. In the context of the Chinese calendar, horology involves the definition and mathematical measurement of terms or elements such observable astronomic movements or events such as are associated with days, months, years, hours, and so on. These measurements are based upon objective, observable phenomena. Calendar accuracy is based upon accuracy and precision of measurements.

The Chinese calendar is lunisolar, similar to the Hindu, Hebrew and ancient Babylonian calendars. In this case the calendar is in part based in objective, observable phenomena and in part by mathematical analysis to correlate the observed phenomena. Lunisolar calendars especially attempt to correlate the solar and lunar cycles, but other considerations can be agricultural and seasonal or phenological, or religious, or even political.

Basic horologic definitions include that days begin and end at midnight, and months begin on the day of the new moon. Years start on the second (or third) new moon after the winter solstice. Solar terms govern the beginning, middle, and end of each month. A sexagenary cycle, comprising the heavenly stems ( zh, c=干, p=gān) and the earthly branches ( zh, c=支, p=zhī), is used as identification alongside each year and month, including intercalary months or leap months. Months are also annotated as either long ( zh, c=大, l=big for months with 30 days) or short ( zh, c=小, l=small for months with 29 days). There are also other elements of the traditional Chinese calendar.

Day

Days are Sun oriented, based upon divisions of the solar year. A day ( zh, labels=no, c=日, p=rì) is considered both traditionally and currently to be the time from one midnight to the next. Traditionally days (including the night-time portion) were divided into 12 double-hours, and in modern times the 24 hour system has become more standard.

Week

As early as the Bronze Age Xia dynasty, days were grouped into nine- or ten-day weeks known as zh, labels=no, c=旬, , p=xún, out=p. Months consisted of three . The first 10 days were the early ( zh, labels=no, c= ), the middle 10 the mid ( zh, labels=no, c= ), and the last nine (or 10) days were the late ( zh, labels=no, c= ). Japan adopted this pattern, with 10-day-weeks known as . In Korea, they were known as ''sun'' (,).

The structure of led to public holidays every five or ten days. Officials of the Han dynasty were legally required to rest every five days (twice a , or 5–6 times a month). The name of these breaks became zh, labels=no, t= , s= , l=wash , p=huàn , out=p.

Grouping days into sets of ten is still used today in referring to specific natural events. "Three Fu" (), a 29–30-day period which is the hottest of the year, reflects its three- length. , script-title=zh:「冷在三九，熱在三伏」 , trans-title=Cold is in the Three Nines, heat is in the Three Fu , website=Educational Resources – Hong Kong Observatory , language=zh , access-date=15 May 2018 , archive-url=https://web.archive.org/web/20180615134946/http://www.hko.gov.hk/prtver/html/docs/education/edu01met/wxobs/folklore/ele_hs_c.shtml , archive-date=15 June 2018 , url-status=dead After the winter solstice, nine sets of nine days were counted to calculate the end of winter.

The seven-day week was adopted from the Hellenistic system by the 4th century CE, although its method of transmission into China is unclear. It was again transmitted to China in the 8th century by Manichaeans via Kangju (a Central Asian kingdom near Samarkand),), an astrologer of the Jin dynasty. and is the most-used system in modern China.

Month

Months are Moon oriented. ''Month'' ( zh, labels=no, c=月, p=yuè), the time from one new moon to the next. These synodic months are about days long. This includes the ''Date'' ( zh, labels=no, c=日期, p=rìqī), when a day occurs in the month. Days are numbered in sequence from 1 to 29 (or 30). And, a ''Calendar month'' ( zh, labels=no, c=日曆月, p=rìlì yuè), is when a month occurs within a year. Some months may be repeated.

Months are defined by the time between new moons, which averages approximately days. There is no specified length of any particular Chinese month, so the first month could have 29 days (short month, ) in some years and 30 days (long month, ) in other years.

Since the beginning of the month is determined by when the new moon occurs, other countries using this calendar use their own time standards to calculate it; this results in deviations. The first new moon in 1968 was at 16:29 UTC on 29 January. Since North Vietnam used UTC+07:00 to calculate their Vietnamese calendar and South Vietnam used UTC+08:00 (Beijing time) to calculate theirs, North Vietnam began the Tết holiday at 29 January at 23:29 while South Vietnam began it on 30 January at 00:15. The time difference allowed asynchronous attacks in the Tet Offensive.

Because astronomical observation determines month length, dates on the calendar correspond to moon phases. The first day of each month is the new moon. On the seventh or eighth day of each month, the first-quarter moon is visible in the afternoon and early evening. On the 15th or 16th day of each month, the full moon is visible all night. On the 22nd or 23rd day of each month, the last-quarter moon is visible late at night and in the morning.

Different eras used different systems to determine the length of each month. The synodic month of the Taichu calendar was days long. The 7th-century, Tang-dynasty Wùyín Yuán Calendar was the first to determine month length by synodic month instead of the cycling method. Since then, month lengths have primarily been determined by observation and prediction.

The days of the month are always written with two characters and numbered beginning with 1. Days one to 10 are written with the day's numeral, preceded by the character ''Chū'' (); ''Chūyī'' () is the first day of the month, and ''Chūshí'' () the 10th. Days 11 to 20 are written as regular Chinese numerals; ''Shíwǔ'' () is the 15th day of the month, and ''Èrshí'' () the 20th. Days 21 to 29 are written with the character ''Niàn'' () before the characters one through nine; ''Niànsān'' (), for example, is the 23rd day of the month. Day 30 (when applicable) is written as the numeral ''Sānshí'' ().

Year

A year ( zh, labels=no, c=年, p=nián) is based upon the time of one revolution of Earth around the Sun, rounded to whole days. Traditionally, the year is measured from the first day of spring (lunisolar year) or the winter solstice (solar year).

A 12-month-year using this system has 354 days, which would drift significantly from the tropical year. To fix this, traditional Chinese years have a 13-month year approximately once every three years. The 13-month version has the same long and short months alternating, but adds a 30-day leap month ( zh, labels=no, c=, p=rùnyuè). Years with 12 months are called common years, and 13-month years are known as long years.

A solar year is astronomically about days. A lunisolar calendar year is either 353–355 or 383–385 days long. The lunisolar calendar ( zh, labels=no, c=日曆, p=rìlì) year usually begins on the new moon closest to Lichun, the first day of spring. This is typically the second and sometimes third new moon after the winter solstice.

The lunisolar year begins with the first spring month, ( zh, labels=no, c=, l=capital month), and ends with the last winter month, ( zh, labels=no, s=, t=, l=sacrificial month). All other months are named for their number in the month order. See below on the timing of the Chinese New Year.

Solar year and solar terms

The solar year ( zh, s=岁, t=歲, p=Suì), the time between winter solstices, is divided into 24 solar terms known as zh, labels=no, out=p, p=jié qì, c=節氣. Each term is a 15° portion of the ecliptic. These solar terms mark both Western and Chinese seasons, as well as equinoxes, solstices, and other Chinese events. Pairs of solar terms are referred to as climate terms. The first solar term in a pair is the "pre-climate" ( zh, labels=no, s=节气, t=節氣, p=Jiéqì), and the second is the "mid-climate" ( zh, labels=no, s=中气, t=中氣, p=Zhōngqì). The are considered "major terms", while the are deemed "minor terms". The solar terms zh, labels=no, out=p, p=qīng míng, c=清明 on 5 April and zh, labels=no, out=p, p=dōng zhì , c=冬至 on 22 December are both celebrated events in China.

The solar year (''suì'', zh, labels=no, t=歲, s=岁) begins on the December solstice and proceeds through the 24 solar terms. Since the speed of the Sun's apparent motion in the elliptical is variable, the time between major terms/mid-climates is not fixed. This variation in time between major terms results in different solar year lengths. There are generally 11 or 12 complete lunisolar months, plus two incomplete lunisolar months around the winter solstice, in a solar year. The complete lunisolar months are numbered from 0 to 10, and the incomplete lunisolar month is considered the 11th month. If there are 12 complete (and one incomplete) lunisolar months within a solar year, it is known as a leap year (a year possessing an intercalary month).

Different versions of the traditional calendar might have different average solar year lengths. For example, one solar year of the 1st century BCE Tàichū calendar is (365.25016) days. A solar year of the 13th-century Shòushí calendar is (365.2425) days, identical to the Gregorian calendar. The additional .00766 day from the Tàichū calendar leads to a one-day shift every 130.5 years.

If there are 12 complete lunisolar months within a solar year, the first lunisolar month that does not contain any mid-climate is designated the leap, or intercalary, month. Leap months are numbered with , the character for "intercalary", plus the name of the month they follow. In 2017, the intercalary month after month six was called , or "intercalary sixth month" () and written as ''6i'' or ''6+''. The next intercalary month (in 2020, after month four) will be called () and written ''4i'' or ''4+''.

Planets

The movements of the Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn (sometimes known as the seven luminaries) are the references for calendar calculations.
* The distance between Mercury and the sun is less than 30° (the sun's height at ''chénshí'':, 8:00 to 10:00 am), so Mercury was sometimes called the "chen star" (); it is more commonly known as the "water star" ().
* Venus appears at dawn and dusk and is known as the "bright star" ( zh, labels=no, s=, t= ) or "long star" ( zh, labels=no, c=, s=, t= ).
* Mars looks like fire and occurs irregularly, and is known as the "fire star" ( zh, labels=no, c=, s=, t= or ). Mars is the punisher in Chinese mythology. When Mars is near Antares (), it is a bad omen and can forecast an emperor's death or a chancellor's removal ().
* Jupiter's revolution period is 11.86 years, so Jupiter is called the "age star" ( zh, labels=no, c=, s=, t= ); 30° of Jupiter's revolution is about a year on earth.
* Saturn's revolution period is about 28 years. Known as the "guard star" (), Saturn guards one of the 28 Mansions every year.

Stars

Big Dipper

The Big Dipper is the celestial compass, and its handle's direction indicates the season and month.

3 Enclosures and 28 Mansions

The stars are divided into Three Enclosures and 28 Mansions according to their location in the sky relative to Ursa Minor, at the center. Each mansion is named with a character describing the shape of its principal asterism. The Three Enclosures are Purple Forbidden, (), Supreme Palace (), and Heavenly Market (). The eastern mansions are . Southern mansions are . Western mansions are . Northern mansions are . The moon moves through about one lunar mansion per day, so the 28 mansions were also used to count days. In the Tang dynasty, Yuan Tiangang () matched the 28 mansions, seven luminaries and yearly animal signs to yield combinations such as "horn-wood-flood dragon" ().

= List of lunar mansions

=

The names and determinative stars of the mansions are:
})
Spring
, 1 , , zh, labels=no, c=角, p=Jiǎo , , Horn , , α Vir
, -
, 2 , , zh, labels=no, c=亢 , p=Kàng , , Neck , , κ Vir
, -
, 3 , , zh, labels=no, c=氐 , p=Dī , , Root , , α Lib
, -
, 4 , , zh, labels=no, c=房 , p=Fáng , , Room , , π Sco
, -
, 5 , , zh, labels=no, c=心 , p=Xīn , , Heart , , α Sco
, -
, 6 , , zh, labels=no, c=尾 , p=Wěi , , Tail , , μ¹ Sco
, -
, 7 , , zh, labels=no, c=箕 , p=Jī , , Winnowing Basket , , γ Sgr
, -
, rowspan="7" , Black Tortoise
of the North
( zh, labels=no, c=北方玄武, p=Běifāng Xuánwǔ)
Winter

, 8 , , zh, labels=no, c=斗 , p=Dǒu , , (Southern) Dipper , , φ Sgr
, -
, 9 , , zh, labels=no, c=牛 , p=Niú , , Ox , , β Cap
, -
, 10 , , zh, labels=no, c=女 , p=Nǚ , , Girl , , ε Aqr
, -
, 11 , , zh, labels=no, c=虛 , p=Xū , , Emptiness , , β Aqr
, -
, 12 , , zh, labels=no, c=危 , p=Wēi , , Rooftop , , α Aqr
, -
, 13 , , zh, labels=no, c=室 , p=Shì , , Encampment , , α Peg
, -
, 14 , , zh, labels=no, c=壁 , p=Bì , , Wall , , γ Peg
, -
, rowspan="7" , White Tiger
of the West
( zh, labels=no, c=西方白虎, p=Xīfāng Báihǔ)
Fall

, 15 , , zh, labels=no, c=奎 , p=Kuí , , Legs , , η And
, -
, 16 , , zh, labels=no, c=婁 , p=Lóu , , Bond , , β Ari
, -
, 17 , , zh, labels=no, c=胃 , p=Wèi , , Stomach , , 35 Ari
, -
, 18 , , zh, labels=no, c=昴 , p=Mǎo , , Hairy Head , , 17 Tau
, -
, 19 , , zh, labels=no, c=畢, p=Bì , , Net , , ε Tau
, -
, 20 , , zh, labels=no, c=觜 , p=Zī , , Turtle Beak , , λ Ori
, -
, 21 , , zh, labels=no, c=参 , p=Shēn , , Three Stars , , ζ Ori
, -
, rowspan="7" , Vermilion Bird
of the South
( zh, labels=no, c=南方朱雀 , p=Nánfāng Zhūquè)
Summer

, 22 , , zh, labels=no, c=井 , p=Jǐng , , Well , , μ Gem
, -
, 23 , , zh, labels=no, c=鬼 , p=Guǐ , , Ghost , , θ Cnc
, -
, 24 , , zh, labels=no, c=柳 , p=Liǔ , , Willow , , δ Hya
, -
, 25 , , zh, labels=no, c=星 , p=Xīng , , Star , , α Hya
, -
, 26 , , zh, labels=no, c=張 , p=Zhāng , , Extended Net , , υ¹ Hya
, -
, 27 , , zh, labels=no, c=翼 , p=Yì , , Wings , , α Crt
, -
, 28 , , zh, labels=no, c=軫 , p=Zhěn , , Chariot , , γ Crv

Sexagenary system

Several coding systems are used to avoid ambiguity. The Heavenly Stems is a decimal system. The Earthly Branches, a duodecimal system, mark dual hours ( zh, labels=no, p=shí, t=, s= or zh, labels=no, p=shíchen, t=, s= ) and climatic terms. The 12 characters progress from the first day with the same branch as the month (first day () of ; first day () of ), and count the days of the month.

Years, months, days of the month and hours could traditionally numbered by the terminology of the Chinese sexagenary cycle.

The stem-branches is a sexagesimal system. The Heavenly Stems and Earthly Branches make up 60 stem-branches. The stem branches mark days and years. The five Wu Xing elements are assigned to each stem, branch, or stem branch.

For example, the year from 12 February 2021 to 31 January 2022 was a year () of 12 months or 354 days. The 60 stem-branches have been used to mark the year since the Shang dynasty (1600 BCE – 1046 BCE). Astrologers knew that the orbital period of Jupiter is about 12×361 = 4332 days, which they divided into 12 years ( zh, labels=no, s=岁, t=歲, p=suì) of 361 days each. The stem-branches system solved the era system's problem of unequal reign lengths.

Current naming conventions use numbers as the month names, although each month is also associated with one of the twelve Earthly Branches. Correspondences with Gregorian dates are approximate and should be used with caution. Many years have intercalary months.

Historically, Chinese had days of the month numbered with the 60 stem-branches:

Fortune-tellers identify the heavenly stem and earthly branch corresponding to a particular day in the month, and those corresponding to its month, and those to its year, to determine the Four Pillars of Destiny associated with it, for which the Tung Shing, also referred to as the Chinese Almanac of the year, or the Huangli, and containing the essential information concerning Chinese astrology, is the most convenient publication to consult. Days rotate through a sexagenary cycle marked by coordination between heavenly stems and earthly branches, hence the referral to the Four Pillars of Destiny as, "Bazi", or " Birth Time Eight Characters", with each pillar consisting of a character for its corresponding heavenly stem, and another for its earthly branch. Since Huangli days are sexagenaric, their order is quite independent of their numeric order in each month, and of their numeric order within a week (referred to as True Animals in relation to the Chinese zodiac). Therefore, it does require painstaking calculation for one to arrive at the Four Pillars of Destiny of a particular given date, which rarely outpaces the convenience of simply consulting the Huangli by looking up its Gregorian date.

The Tang dynasty used the Earthly Branches to mark the months from December 761 to May 762. Over this period, the year began with the winter solstice.

China has used the Western hour-minute-second system to divide the day since the Qing dynasty. Several systems were in use historically; systems using multiples of twelve and ten were popular, since they could be easily counted and aligned with the Heavenly Stems and Earthly Branches.

Age reckoning

In modern China, a person's official age is based on the Gregorian calendar. For traditional use, age is based on the Chinese ''Sui'' calendar. A child is considered one year old at birth. After each Chinese New Year, one year is added to their traditional age. Their age therefore is the number of Chinese calendar years in which they have lived. Due to the potential for confusion, the age of infants is often given in months instead of years.

After the Gregorian calendar was introduced in China, the Chinese traditional-age was referred to as the "nominal age" ( zh, labels=no , t=虛歲 , s=虚岁, p=xūsuì, l=incomplete age) and the Gregorian age was known as the "real age" ( zh, labels=no , t=實歲 , s=实岁 , p=shísùi , l=whole age).

Holidays

Various traditional and religious holidays shared by communities throughout the world use the Chinese (Lunisolar) calendar:

Chinese New Year

The date of the Chinese New Year accords with the patterns of the lunisolar calendar and hence is variable from year to year.

The invariant between years is that the winter solstice, Dongzhi is required to be in the eleventh month of the year This means that Chinese New Year will be on the second new moon after the previous winter solstice, unless there is a leap month 11 or 12 in the previous year.

This rule is accurate, however there are two other mostly (but not completely) accurate rules that are commonly stated:

* The new year is on the new moon closest to Lichun (typically 4 February).
* The new year is on the first new moon after Dahan (typically 20 January)

It has been found that Chinese New Year moves back by either 10, 11, or 12 days in most years. If it falls on or before 31 January, then it moves forward in the next year by either 18, 19, or 20 days.

Holidays with the same day and same month

The Chinese New Year (known as the Spring Festival/ in China) is on the first day of the first month and was traditionally called the Yuan Dan () or Zheng Ri (). In Vietnam it is known as Tết Nguyên Đán (). Traditionally it was the most important holiday of the year. It is an official holiday in China including Hong Kong, Macau, and Taiwan regions,and, Vietnam, Korea, the Philippines, Malaysia, Singapore, Indonesia, and Mauritius. It is also a public holiday in Thailand's Narathiwat, Pattani, Yala and Satun provinces, and is an official public school holiday in New York City.

The Double Third Festival is on the third day of the third month.

The Dragon Boat Festival, or the Duanwu Festival (), is on the fifth day of the fifth month and is an official holiday in China including Hong Kong, Macau, and Taiwan regions.

The Qixi Festival () is celebrated in the evening of the seventh day of the seventh month.

The Double Ninth Festival () is celebrated on the ninth day of the ninth month.

Full moon holidays (holidays on the fifteenth day)

The Lantern Festival is celebrated on the fifteenth day of the first month and was traditionally called the Yuan Xiao () or Shang Yuan Festival ().

The Zhong Yuan Festival is celebrated on the fifteenth day of the seventh month.

The Mid-Autumn Festival is celebrated on the fifteenth day of the eighth month.

The Xia Yuan Festival is celebrated on the fifteenth day of the tenth month.

Celebrations of the twelfth month

The Laba Festival is on the eighth day of the twelfth month. It is the enlightenment day of Sakyamuni Buddha and in Vietnam is known as .

The Kitchen God Festival is celebrated on the twenty-third day of the twelfth month in northern regions of China and on the twenty-fourth day of the twelfth month in southern regions of China.

Chinese New Year's Eve is also known as the Chuxi Festival and is celebrated on the evening of the last day of the traditional Chinese calendar. It is celebrated wherever the traditional Chinese calendar is observed.

Celebrations of solar-term holidays

The Qingming Festival () is celebrated on the fifteenth day after the Spring Equinox.

The Dongzhi Festival () or the Winter Solstice is celebrated.

Religious holidays based on the Chinese calendar

East Asian Mahayana, Daoist, and some Cao Dai holidays and/or vegetarian observances are based on the traditional Chinese calendar.

Celebrations in Japan

Many of the above holidays of the traditional Chinese calendar are also celebrated in Japan, but since the Meiji era on the similarly numbered dates of the Gregorian calendar.

Double celebrations due to intercalary months

In the case when there is a corresponding intercalary month, the holidays may be celebrated twice. For example, in the hypothetical situation in which there is an additional intercalary seventh month, the Zhong Yuan Festival will be celebrated in the seventh month followed by another celebration in the intercalary seventh month. The next such occasion will be 2044 (before: 2033 is 11th month), the first such since the calendar reform of 1645.

Similar calendars

Like Chinese characters, variants of the Chinese calendar have been used in different parts of the Sinosphere throughout history: this includes Vietnam, Korea, Singapore, Japan and Ryukyu, Mongolia, and elsewhere.

Outlying areas of China

Calendars of ethnic groups in mountains and plateaus of southwestern China and grasslands of northern China are based on their phenology and algorithms of traditional calendars of different periods, particularly the Tang and pre-Qin dynasties.

Non-Chinese areas

Korea, Vietnam, and the Ryukyu Islands adopted the Chinese calendar. In the respective regions, the Chinese calendar has been adapted into the Korean, Vietnamese, and Ryukyuan calendars, with the main difference from the Chinese calendar being the use of different meridians due to geography, leading to some astronomical events — and calendar events based on them — falling on different dates. The traditional Japanese calendar was also derived from the Chinese calendar (based on a Japanese meridian), but Japan abolished its official use in 1873 after Meiji Restoration reforms. Calendars in Mongolia and Tibet have absorbed elements of the traditional Chinese calendar but are not direct descendants of it.

See also

* Chinese calendar correspondence table
* Guo Shoujing, an astronomer tasked with calendar reform during the 13th century
* List of festivals in Asia
* Metonic cycle of 19 years is used to reckon leap years with intercalary months in the Hebrew and Babylonian calendars

Notes

References

Sources

*
*
*

Further reading

*

External links

; Calendars

Chinese months


(1901–2100)

Chinese calendar and holidays

Chinese calendar with Auspicious Events

Chinese Calendar Online

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2000-year Chinese-Western calendar converter
From 1 CE to 2100 CE. Useful for historical studies. To use, put the western year 年 month 月day 日in the bottom row and click on 執行.

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