Imperial units are units of measures. They are also referred to as the British Imperial System. The system was first used officially in 1824 in Great Britain. The traditional system of measures was later dropped for the metric system in 1965. The British Imperial System has influenced the United States Customary System. Today, imperial units are legally defined as metric terms. If you are interested in inches to centimeters, you need to read on.


Early Origins

The history of the British Imperial System goes back thousands of years as it has evolved from interactions between the Anglo-Saxon, Celtic, and Romans. It was the customary system for measuring units in the middle ages. Traditional names like gallon, foot, and pound continue to be used. However, their values have changed over time. Moreover, there are differences due to product specifications, trade, place, and time.

Winchester was the initial name established for the early royal standards. It ensured that the standards were enforced. The name was after the ancient capital of Britain. It is where Edgar the Peaceable, the 10th Century Saxon king kept a royal bushel measure and others. A yard was recorded by the 14th century statutes as a stick measuring 3 feet. They mentioned that each foot contained 12 inches and each inch would equal to the length of 3 barleycorns. Thus, the employment of a learning device was made. Similarly, units of weights and capacity were also specified.

The customary Winchester standards for length and capacity were later reaffirmed by King Henry VII during late 15th century. They are distributed as royal standards throughout the realm. Later in the 16th century, Queen Elizabeth I repeated the process during her reign. A rod was defined as measuring 16.5 feet or 5.5 yards.

Statutes were later passed in the 17th century which established the furlong, rod, and acre at their present values of 66o feet, 16.5 feet, and 4,840 square yards. There used to be several trade pounds that were commonly used which were then reduced to only two, namely the pound avoirdupois for other goods and the troy pound for precious metals.


The Establishment of the System

The British Imperial System was established by the Weights and Measures Act of 1824. It further reemerged through the Act of 1978. The Act clearly defined the definitions of the existing units. A single imperial gallon was sanctioned by the 1824 Act to replace corn, ale, and wine gallons.

The new gallon was described as being equal to 10 pounds avoirdupois. The troy pound and the imperial standard yard were the two new basic standard units which were later restricted jewels, precious metals, and drugs. Archaic measures like the cauldron and rod were abolished by the 1963 Act.



As the British reformed their measures and weights in the 19th century, it was the Americans who had only started to adopt units from the discarded act of 1824. Thus, it shows how both countries evolved into adopting their own systems.