The imperial system of units, imperial system or imperial units 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.
Metrication or metrification is the act or process of converting to the metric system of measurement. All over the world, countries have transitioned from local and traditional units of measurement to the metric system. This process began in France during the 1790s, and is still continuing more than 200 years later, with the modern International System of Units, as the metric system has not been fully adopted in all countries and areas.
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 was overhauled in 1824 to create the imperial system, 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 significant differences between the systems.
The pint is a unit of volume or capacity in both the imperial and United States customary measurement systems. In both of those systems it is traditionally one eighth of a gallon. The British imperial pint is about 20% larger than the American 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, the volume varies by regional custom.
A unit of length refers to any arbitrarily chosen and accepted reference standard for measurement of length. The most common units in modern use are the metric units, used in every country globally. In the United States the U.S. customary units are also in use. British Imperial units are still used for some purposes in the United Kingdom and some other countries. The metric system is sub-divided into SI and non-SI units.
Metrication is the process of introducing the International System of Units, also known as SI units or the metric system, to replace a jurisdiction's traditional measuring units. U.S. customary units have been defined in terms of metric units since the 19th century, and the SI has been the "preferred system of weights and measures for United States trade and commerce" since 1975 according to United States law. However, conversion was not mandatory and many industries chose not to convert, and U.S. customary units remain in common use in many industries as well as in governmental use. There is government policy and metric (SI) program to implement and assist with metrification, however there is major social resistance for further metrication.
The "Plan for Establishing Uniformity in the Coinage, Weights, and Measures of the United States" was a report submitted to the U.S. House of Representatives on July 13, 1790, by Secretary of State Thomas Jefferson.
A system of units of measurement, also known as a system of units or system of measurement, is a collection of units of measurement and rules relating them to each other. Systems of measurement have historically been important, regulated and defined for the purposes of science and commerce. Instances in use include the International System of Units or SI, the British imperial system, and the United States customary system.
The spread of metrication around the world in the last two centuries has been met with both support and opposition.
Metrication in Canada began in 1970 and ceased in 1985. While Canada has converted to the metric system for many purposes, there is still significant use of non-metric units and standards in many sectors of the Canadian economy and everyday life today. This is mainly due to historical ties with the United Kingdom, the traditional use of the imperial system of measurement in Canada, proximity to the United States, and strong public opposition to metrication during the transition period.
Metrication in Australia effectively began in 1966 with the conversion to decimal currency under the auspices of the Decimal Currency Board. The conversion of measurements—metrication—commenced subsequently in 1971, under the direction of the Metric Conversion Board and actively proceeded until the Board was disbanded in 1981.
Metrication, the process of introducing the metric system of measurement in place of imperial units, has made steady progress in the United Kingdom since the mid-20th century but today remains equivocal and varies by context. Most of government, industry and commerce use metric units. Imperial units are officially used to specify journey distances, vehicle speeds and the sizes of returnable milk containers, beer and cider glasses, fresh milk is often still sold in multiples of pints, with the metric equivalent also marked, and precious metals are sold by the troy ounce. Metric measurements must be used when selling other packaged or loose goods. Imperial measurement can stand alongside the metric measurement but it cannot stand out more than the metric measurement. Imperial units are also often used to describe body measurements and vehicle fuel economy. In schools, metric units, and Imperial units that still remain in common usage in the UK are taught.
The earliest recorded systems of weights and measures originate in the 3rd or 4th millennium BC. Even the very earliest civilizations needed measurement for purposes of agriculture, construction and trade. Early standard units might only have applied to a single community or small region, with every area developing its own standards for lengths, areas, volumes and masses. Often such systems were closely tied to one field of use, so that volume measures used, for example, for dry grains were unrelated to those for liquids, with neither bearing any particular relationship to units of length used for measuring cloth or land. With development of manufacturing technologies, and the growing importance of trade between communities and ultimately across the Earth, standardized weights and measures became critical. Starting in the 18th century, modernized, simplified and uniform systems of weights and measures were developed, with the fundamental units defined by ever more precise methods in the science of metrology. The discovery and application of electricity was one factor motivating the development of standardized internationally applicable units.
Traditional Japanese units of measurement or the shakkanhō (尺貫法) is the traditional system of measurement used by the people of the Japanese archipelago. It is largely based on the Chinese system, which spread to Japan and the rest of the Sinosphere in antiquity. It has remained mostly unaltered since the adoption of the measures of the Tang dynasty in 701. Following the 1868 Meiji Restoration, Imperial Japan adopted the metric system and defined the traditional units in metric terms on the basis of a prototype metre and kilogram. The present values of most Korean and Taiwanese units of measurement derive from these values as well.
Metrication in the Republic of Ireland happened mostly in the 20th century and was officially completed in 2005, with a few exceptions.
New Zealand started metrication in 1969 with the establishment of the Metric Advisory Board (MAB) and completed metrication on 14 December 1976. Until the 1970s, New Zealand traditionally used the imperial system for measurement, which it had inherited from the United Kingdom.
The history of measurement systems in India begins in early Indus Valley civilisation with the earliest surviving samples dated to the 5th millennium BCE. Since early times the adoption of standard weights and measures has reflected in the country's architectural, folk, and metallurgical artifacts. A complex system of weights and measures was adopted by the Maurya empire, which also formulated regulations for the usage of this system. Later, the Mughal empire (1526–1857) used standard measures to determine land holdings and collect land tax as a part of Mughal land reforms. The formal metrication in India is dated to 1 October 1958 when the Indian Government adopted the International System of Units (SI).
Sweden decided to adopt the metric system in 1876. After a ten-year transition period starting 1879, the use of legacy units was outlawed by the beginning of 1889.
The following outline is provided as an overview of and topical guide to the metric system:
The imperial and US customary measurement systems are both derived from an earlier English system of measurement which in turn can be traced back to Ancient Roman units of measurement, and Carolingian and Saxon units of measure.
