Historiaa

English units are the historical units of measurement used in England up to 1824, which evolved as a combination of the Anglo-Saxon and Roman systems of units. They were redefined in the UnitedKingdom in 1824 by a Weights and Measures Act, which retained many but not all of the unit names with slightly different values, and again in the 1970s by the International System of Units as a subset ofthe metric system. In modern UK usage, the term is considered ambiguous, as it could refer either to the imperial system used in the UK, or to the US customary system of unit. The common term used inthe UK for the non-metric system is imperial units or imperial measurements, since they were used as a standard throughout the British Empire and the Commonwealth.

Within the United States, thesame term is commonly used to refer to the United States Customary System,[1] which retains some unit names but with different values, as well as to the imperial units.

Various standards have appliedto English units at different times, in different places, and for different applications.

Very little is known of the measurement units of the British Isles prior to Roman colonization in the 1stcentury CE. During the Roman period, Roman Britain relied on Ancient Roman units of measurement. During the Anglo-Saxon period, the North German foot of 335 millimeters (13.2 inches) was the nominalbasis for other units of linear measurement. The foot was divided into 4 palms or 12 thumbs. A cubit was 2 feet, an elne 4 feet. The rod was 15 Anglo-Saxon feet, the furlong 10 rods. An acre was 4 ×40 rods, i.e., 160 square rods or 36,000 square Anglo-Saxon feet. However, Roman units continued to be used in the construction crafts. From the time of Offa King of Mercia (8th c.) until 1526 theSaxon pound, also known as the moneyers' pound (and later known as the Tower pound) was the fundamental unit of mass measurement.

Prior to the enactment of a law known as the Composition of Yards...