Liang (simplified Chinese: 两; traditional Chinese: 兩; pinyin: liǎng), or leung in Cantonese, also called "Chinese ounce" or "tael"[a], is a traditional Chinese unit for weight measurement. It originated in China before being introduced to neighboring countries in East Asia.
Nowaday, the mass of 1 liang equals 50 grams in mainland China,[2] 37.5 grams in Taiwan, Korea and Thailand,
[3][4]
37.799 grams in Hong Kong, Singapore and Malaysia,[5][6][7] and 100 grams in Vietnam.[8]
Liang is mostly used in the traditional markets, and famous for measuring gold, silver and Chinese medicines.
[2][4]
China Mainland
Chinese mass units promulgated in 1915
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 measures based directly on the Qing dynasty definitions (营造尺库平制).[9]
Table of Chinese mass units promulgated in 1915[9]
where liang is the base unit equal to 37.301 grams.
Mass units in the Republic of China since 1930
On 16 February 1929, the Nationalist government adopted and promulgated The Weights and Measures Act[10] to adopt the metric system as the official standard and to limit the newer Chinese units of measurement to private sales and trade, effective on 1 January 1930. These newer "market" units are based on rounded metric numbers. And jin became the base unit.[11]
Table of mass units in the Republic of China since 1930[11]
where liang is equal to 1/16 of a jin, or 31.25 grams.
Mass units in the People's Republic of China since 1959
On June 25, 1959, the State Council of the People's Republic of China issued the "Order on the Unified Measurement System", retaining the market measure system, with the statement of "The market system originally stated that sixteen liangs are equal to one jin. Due to the trouble of conversion, it should be changed to ten liangs per jin. "[12]
Table of mass units in the People's Republic of China since 1959[2]
Legally, 1 jin equals 500 grams, and 10 liangs equals 1 jin (that is, 1 liang equals 50 grams). The traditional Chinese medicine measurement system remains unchanged.[2]
Taiwan
In 1895, Taiwan was ceded to Japan from China. The Japanese implemented the metric system, but the Taiwanese still followed their own habits and continued to use the old weights and measures of the Qing Dynasty. 1 Taiwan liang is equal to 37.5 grams, or 1/16 Taiwan jin.
[14]
Similarly, Singapore law stipulates that one jin is also equal to sixteen liangs or 0.6048 kilograms, and one liang equals to 37.799 g.[6] Malaysia has the same regulations as it is a former British colony.
Hong Kong troy units
These are used for trading precious metals such as gold and silver.
^ ab"權度法 [Quándù Fǎ]", 政府公報 [Zhèngfǔ Gōngbào, Government Gazette], vol. 957, Beijing: Office of the President, 7 January 1915, pp. 85–94[permanent dead link](in Chinese)