Chinese units of measurement

Chinese units of measurement, known in Chinese as the shìzhì ("market system"), are the traditional units of measurement of the Han Chinese. Although Chinese numerals have been decimal (base-10) since the Shang, several Chinese measures use hexadecimal (base-16). Local applications have varied, but the Chinese dynasties usually proclaimed standard measurements and recorded their predecessor's systems in their histories.

In the present day, the People's Republic of China maintains some customary units based upon the market units but standardized to round values in the metric system, for example the common jin or catty of exactly 500g. The Chinese name for most metric units is based on that of the closest traditional unit; when confusion might arise, the word "market" (, shì) is used to specify the traditional unit and "common" or "public" (, gōng) is used for the metric value. Taiwan, like Korea, saw its traditional units standardized to Japanese values and their conversion to a metric basis, such as the Taiwanese ping of about 3.306m2 based on the square ken. The Hong Kong SAR continues to use its traditional units, now legally defined based on a local equation with metric units. For instance, the Hong Kong catty is precisely $604.79 g$.

Note: The names lí (釐 or 厘) and fēn (分) for small units are the same for length, area, and mass; however, they refer to different kinds of measurements.

History


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 (营造尺库平制).

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.

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.

Length
Traditional units of length include the chi (尺), bu (步), and li (里). 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.

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.

Metric length units
The Chinese word for metre is 米 mǐ; this can take the Chinese standard SI prefixes (for "kilo-", "centi-", etc.). A kilometre, however, may also be called 公里 gōnglǐ, i.e. a metric lǐ.

In the engineering field, traditional units are rounded up to metric units. For example, the Chinese word 絲 (T) or 丝 (S) sī is used to express 0.01 mm.

Hong Kong and Macau length units
These correspond to the measures listed simply as "China" in The Measures, Weights, & Moneys of All Nations

Metric and other area units
Metric and other standard length units can be squared by the addition of the prefix 平方 píngfāng. For example, a square kilometre is 平方公里 píngfāng gōnglǐ.

Volume
These units are used to measure cereal grains, among other things. In imperial times, the physical standard for these was the jialiang.

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 立方 lìfāng ("cubic"), as in 立方米 lìfāng mǐ for one cubic metre.

Mass
These units are used to measure the mass of objects. They are also famous for measuring monetary objects such as gold and silver.

Metric mass units
The Chinese word for gram is 克 kè; this can take the Chinese standard SI prefixes (for "milli-", "deca-", and so on). A kilogram, however, is commonly called 公斤 gōngjīn, i.e. a metric jīn.

Hong Kong troy units
These are used for trading precious metals such as gold and silver.

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. Qiu Guangming & Zhang Yanming's 2005 bilingual Concise History of Ancient Chinese Measures and Weights summarizes these findings. 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.