The traditional Chinese calendar (also known as the Agricultural Calendar [農曆; 农历; Nónglì; 'farming calendar'], Former Calendar [舊曆; 旧历; Jiùlì], Traditional Calendar [老曆; 老历; Lǎolì]), is a lunisolar calendar which identifies years, months, and days according to astronomical phenomena. In China, it 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 May 12, 2017.
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This article is missing information about publications from astronomical
(南京紫金山天文台 in PRC, 國立中央研究院天文研究所 in the ROC); 2033 problem[zh] due to Shíxiàn changes; ROC revisions leading up to 1929 紫金曆 system, on which Taiwanese and Chinese standards are currently based on. (February 2021)
This article is missing information about Improvement across dynasties, especially on ways to mitigate accumulation in error and calculation of leap months placement, and respective situation as adapted across the East Asia outside China, as well as political implication of the various calendar systems, together with history on changes of which month being start of a year. (February 2022)
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 P.R.C. continues to announce the months and dates in both the Gregorian and the traditional lunisolar calendar.
Like Chinese characters, variants of Chinese calendar were used in different parts of the Sinosphere throughout history. Korea, Vietnam, and the Ryukyu Islands adopted the Chinese calendar, and evolved it into Korean, Vietnamese, and Ryukyuan calendars, with the main difference from the Chinese calendar being the use of different meridians due to geography, which leads 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 its official use in Japan was abolished in 1873 due to reforms after the Meiji Restoration. Calendars in Mongolia and Tibet have absorbed elements of the traditional Chinese calendar but are not direct descendants of it.
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 stems (干, gān) and branches (支, zhī), is used as identification alongside each year and month; including intercalary months or leap months. The length of a month is also annotated as either long (大, literally "big" for months with 30 days) or short (小, literally "small" for months with 29 days).