The unit volume or capacity of the sho differs greatly according to the periods and the regions (refer to the article of sho for details), however correlation between the sho and other units has hardly changed from ancient times.
升の大きさは時代や地域によって大きく異なる（詳細は升を参照のこと）が、升と他の単位との関係はほとんど古代から変わっていない。