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).^{[citation needed]} 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 500 g. The Chinese name for most metric units is based on that of the closest traditional unit; when confusion might arise, the word "market" (市, shì) is used to specify the traditional unit and "common" or "public" (公, 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 3.306 m² 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 604.78982 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.

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.

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 (Chinese: 市用制; pinyin: shìyòngzhì; lit. 'market-use system') to private sales and trade in Article 11, effective on 1 January 1930. These newer "market" units are based on rounded metric numbers.