Chinese units of measurement

; Shaanxi History Museum, Xi'an According to the Liji, the legendary Yellow Emperor created the first measurement units. The Xiao Erya and the Kongzi Jiayu state that length units were derived from the human body. According to the Records of the Grand Historian, these human body units caused inconsistency, and Yu the Great, another legendary figure, unified the length measurements. Rulers with decimal units have been unearthed from Shang dynasty tombs. In the Zhou dynasty, the king conferred nobles with powers of the state and the measurement units began to be inconsistent from state to state. After the Warring States period, Qin Shi Huang unified China, and later standardized measurement units. In the Han dynasty, these measurements were still being used, and were documented systematically in the Book of Han. Astronomical instruments show little change of the length of chi in the following centuries, since the calendar needed to be consistent. It was not until the introduction of decimal units in the Ming dynasty that the traditional system was revised. Republican Era On 7 January 1915, the Beiyang government promulgated a measurement law to use not only metric system as the standard but also a set of Chinese-style measurement based directly on the Qing dynasty definitions (). On 16 February 1929, the Nationalist government adopted and promulgated The Weights and Measures Act to adopt the metric system as the official standard and to limit the newer Chinese units of measurement () to private sales and trade in Article 11, effective on 1 January 1930. These newer "market" units are based on rounded metric numbers. These units are still retained for use in the Republic of China-controlled territories of Kinmen and Matsu nowadays. People's Republic of China The Government of the People's Republic of China continued using the market system along with metric system, as decreed by the State Council of the People's Republic of China on 25 June 1959, but 1 catty being 500 grams, would become divided into 10 (new) taels, instead of 16 (old) taels, to be converted from province to province, while exempting Chinese prescription drugs from the conversion to prevent errors. On 27 February 1984, the State Council of the People's Republic of China decreed the market system to remain acceptable until the end of 1990 and ordered the transition to the national legal measures by that time, but farmland measures would be exempt from this mandatory metrication until further investigation and study. Hong Kong In 1976 the Hong Kong Metrication Ordinance allowed a gradual replacement of the system in favor of the International System of Units (SI) metric system. The Weights and Measures Ordinance defines the metric, Imperial, and Chinese units. As of 2012, all three systems are legal for trade and are in widespread use. Macau On 24 August 1992, Macau published Law No. 14/92/M to order that Chinese units of measurement similar to those used in Hong Kong, Imperial units, and United States customary units would be permissible for five years since the effective date of the Law, 1 January 1993, on the condition of indicating the corresponding SI values, then for three more years thereafter, Chinese, Imperial, and US units would be permissible as secondary to the SI. == Ancient Chinese units ==

Length '' = 231 mm. Western Han (206 BCE–8 CE). Hanzhong City Traditional units of length include the chi (), bu (), and li (). The precise length of these units, and the ratios between these units, has varied over time. 1 bu has consisted of either 5 or 6 chi, while 1 li has consisted of 300 or 360 bu. Mass Ancient Chinese weight units are mostly defined around the jin or catty. Blanks in the table means that the derived unit is not used in the era. Time For daytime and nighttime units, the following assume a standardized sundown of yǒu shí central 1 kè (19:12 in 24-hour notation). Volume According to Book of Han, the fundamental unit of volume was the yuè (), the volume of 1200 grains of proso millet. 100 yuè makes a gě (), and 10 gě makes a shēng (, about 0.2 L). For dry measure, the dǒu (, "ladle"), hú (), and shi or dàn (, "[basket for] a stone['s weight]") were used for larger amounts. The amounts of grains were also used as a measure of monthly and annual salary, particularly for official posts in the imperial bureaucracy. The volume units have evolved through the Dynasties. By the Qing Dynasty, the shēng had become very close to the metric liter. == Modern Chinese units ==

All "metric values" given in the tables are exact unless otherwise specified by the approximation sign '~'. Certain units are also listed at List of Chinese classifiers → Measurement units. The units in the following tables can be grouped into a few types: • Traditional-derived units for length, area, volume, and mass. • On the Chinese mainland, these units were defined in three batches. The Republic of China government promulgated in 1915 a metric version of the Qing Dynasty Yingzao Chi Kuping Zhi (). The ROC government then promulgated the "market unit" () system in 1930, redefining traditional units as simple fractions of metric units. Finally, the People's Republic of China modified the "market unit" mass system to divide 1 jin into 10 instead of the traditional 16 liang for ease of calculation. • In Hong Kong and Macau the mass units were defined in terms of the British pound, specifically the 1878 definition of 0.45359 kg. The volume units were inherited from the Qing dynasty units, with a small difference compared to the 1915 definition. The length units were based on the unusually large chi found in the area of Guangdong (see ). The source of the area unit is unknown, as it appears to be based on a different chi of (obtained by taking the square root of the metric value of cek3, the square-chi). • Chinese names for metric units and prefixes. This includes time units. Length Chinese length units promulgated in 1915 Chinese length units effective in 1930 Metric length units The (Mainland) Chinese word for metre is mǐ; this can take the Chinese standard SI prefixes (for "kilo-", "centi-", etc.). There exists, however, a system based on renaming traditional units, rounding them up to the closest metric unit. • For the centimeter and above, the name is constructed as gōng ("public", i.e. metric) followed by the traditional unit name. For example, a kilometre is popularly known as the gōnglǐ "metric lǐ". • For smaller units, a different convention exists in the engineering field. The traditional unit is appropriated without adding the gōng prefix. For example, the Chinese word (T) or (S) sī is used to express 0.01 mm. The Republic of China uses the gōng-prefixed names as the standard, legal names of the corresponding units. Hong Kong and Macau length units These correspond to the measures listed simply as "China" in The Measures, Weights, & Moneys of All Nations. Area Chinese area units promulgated in 1915 Chinese area units effective in 1930 Metric and other area units Metric and other standard length units can be squared by the addition of the prefix píngfāng. For example, a square kilometre is píngfāng gōnglǐ. Macau area units The units cek3 and zoeng6 are also names of traditional length units. This is an ancient practice with Chinese units of measurement, where area units derived by squaring length units simply take on the same name. Modern derivations would add a prefix 方 or 平方 "square". Volume These units are used to measure cereal grains, among other things. In imperial times, the physical standard for these was the jialiang. Chinese volume units promulgated in 1915 Chinese volume units effective in 1930 Metric volume units In the case of volume, the market and metric shēng coincide, being equal to one litre as shown in the table. The Chinese standard SI prefixes (for "milli-", "centi-", etc.) may be added to this word shēng. Units of volume can also be obtained from any standard unit of length using the prefix lìfāng ("cubic"), as in lìfāng mǐ for one cubic metre. Macau volume units Mass These units are used to measure the mass of objects. They are also famous for measuring monetary objects such as gold and silver. Chinese mass units promulgated in 1915 Mass units in the Republic of China since 1930 Mass units in the People's Republic of China since 1959 Metric mass units The Chinese word for gram is kè; this can take the Chinese standard SI prefixes (for "milli-", "deca-", and so on). A kilogram, however, is commonly called gōngjīn, i.e. a metric jīn. The PRC translated the non-SI quintal (100 kg) as gōngdàn ("metric dàn") in 1959, but abandoned the unit in newer publications. Hong Kong and Macau mass units Hong Kong troy units These are used for trading precious metals such as gold and silver. Time Modern Chinese time units largely correspond one-to-one to Western units. In addition to the above units, the ancient shíchén is occasionally used with the value of exactly 2 hours. ==Historiography==

As there were hundreds of unofficial measures in use, the bibliography is quite vast. The editions of Wu Chenglou's 1937 History of Chinese Measurement were the usual standard up to the 1980s or so, but rely mostly on surviving literary accounts. Newer research has put more emphasis on archeological discoveries. A relatively recent and comprehensive bibliography, organized by period studied, has been compiled in 2012 by Cao & al.; for a shorter list, see Wilkinson's year 2000 Chinese History. == See also ==