Kuping 庫平, also called kuping liang 庫平兩 (Kuping tael) or kuping yin 庫平銀 (Kuping silver [ingot]) was a standard weight (see weights and measures) for monetary silver ingots used by the central government institutions in Beijing during the Qing era 清 (1644-1911). It was defined during the Kangxi reign-period 康熙 (1662-1722) and used for measuring and accounting taxes and government expenditure. Like all weights and measures, and also the exchange rate between copper cash and silver ingots, the size of the official weights (guanping 官平) differed from province to province. The largest provincial tael/liang was seen in the province of Guangdong, where it was 0.4736g heavier than the kuping tael, and the lowest one was used in the city of Ningbo 寧波, Zhejiang, where its weight was 0.4463g smaller than that of the official tael. In 1908 the kuping tael was standardized throughout the empire, with an exact weight of 37.301g.
In 1858, the maritime customs tael (guanping 關平) was introduced, as announced in the Treaty of Tiantsin (Zhong-Ying Tianjin tiaoyue 中英天津條約), with a weight of 37.7993g. Yet in practice the weight was not stable and changed somewhat in its exchange rate to other local weights of Shanghai. The customs tael was only abolished in 1930.
In contrast to these official weights, the private markets used the shiping 市平 tael, whose size not only varied from town to town, but also from one transaction to the next. Tianjin and Shanghai, for instance, used the gongfaping tael 公砝平, Hankou 漢口 in Hubei and Guiyang 貴陽 in Guizhou the gongguping tael 公估平, and Guangdong the simaping tael 司馬平. Moneychangers and assayers used the qianping 錢平 tael.