Comparison of the imperial and US customary measurement systems in the context of "Imperial system"

The imperial system of units, imperial system or imperial units (also known as British Imperial or Exchequer Standards of 1826) is the system of units first defined in the British Weights and Measures Act 1824 and continued to be developed through a series of Weights and Measures Acts and amendments.

The imperial system developed from earlier English units as did the related but differing system of customary units of the United States. The imperial units replaced the Winchester Standards, which were in effect from 1588 to 1825. The system came into official use across the British Empire in 1826.

United States customary units form a system of measurement units commonly used in the United States and most U.S. territories since being standardized and adopted in 1832. The United States customary system developed from English units that were in use in the British Empire before the U.S. became an independent country. The United Kingdom's system of measures evolved by 1824 to create the imperial system, with imperial units, which was officially adopted in 1826, changing the definitions of some of its units. Consequently, while many U.S. units are essentially similar to their imperial counterparts, there are noticeable differences between the systems.

The majority of U.S. customary units were redefined in terms of the meter and kilogram with the Mendenhall Order of 1893 and, in practice, for many years before. These definitions were refined by the international yard and pound agreement of 1959.

The pint (/ˈpaɪnt/, listen; symbol pt, sometimes abbreviated as p) is a unit of volume or capacity in both the imperial and United States customary measurement systems. In both of those systems, it is one-eighth of a gallon.

The British imperial pint is 20.095% larger than the US pint because the two systems are defined differently. Almost all other countries have standardized on the metric system, so although some of them still also have traditional units called pints (such as for beverages), the volume varies by regional custom.