101-512: 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
202-483: A barleycorn . A system of measurement is a collection of units of measurement and rules relating them to each other. As science progressed, a need arose to relate the measurement systems of different quantities, like length and weight and volume. The effort of attempting to relate different traditional systems between each other exposed many inconsistencies, and brought about the development of new units and systems. Systems of units vary from country to country. Some of
303-602: A bushel is a fixed volume of 2,150.42 cubic inches (35.2391 liters). The mass of grain will therefore vary according to density. Some nominal weight examples are: The most common practical cooking measures for both liquid and dry ingredients in the U.S. are teaspoon , tablespoon , and cup , along with halves, thirds, quarters, and eighths of each. Units used are pounds , ounces , and fluid ounces . Common sizes are also used, such as can (presumed size varies depending on product), jar , square (e.g. of chocolate), stick (e.g. of butter), or portion of fruit or vegetable (e.g.
404-469: A Federal Register Notice (FRN) indicating the deprecation of the U.S. survey foot and U.S. survey mile units from December 31, 2022. In the following tables in this and subsequent sections, the most common measures are shown in italics , and approximate values are shown in parentheses; values not in parentheses are exact. Note that as announced by the National Institute of Standards and Technology ,
505-503: A US gallon. Consequently, a fluid ounce of water weighs about 1.041 ounces avoirdupois. For nutritional labeling and medicine in the US, the teaspoon and tablespoon are defined as a metric teaspoon and tablespoon—precisely 5 mL and 15 mL respectively. The saying, "a pint's a pound the world around", refers to 16 US fluid ounces of water weighing approximately (about 4% more than) one pound avoirdupois. An imperial pint of water weighs
606-467: A circumference divisible as a whole number into ten long feet. The measures of Iron Age Britain are uncertain and proposed reconstructions such as the Megalithic Yard are controversial. Later Welsh legend credited Dyfnwal Moelmud with the establishment of their units , including a foot of 9 inches. The Belgic or North German foot of 335 mm (13.2 in) was introduced to England either by
707-480: A crucial role in human endeavour from early ages up to the present. A multitude of systems of units used to be very common. Now there is a global standard, the International System of Units (SI), the modern form of the metric system . In trade, weights and measures are often a subject of governmental regulation, to ensure fairness and transparency. The International Bureau of Weights and Measures (BIPM)
808-555: A difference of about 1 ⁄ 8 in (3 mm) per mile – but it affects the definition of the State Plane Coordinate Systems (SPCSs), which can stretch over hundreds of miles. The NAD27 was replaced in the 1980s by the North American Datum of 1983 (NAD83), which is defined in meters. The SPCSs were also updated, but the U.S. National Geodetic Survey left the decision of which (if any) definition of
909-521: A half lemon, two medium onions). Degrees Fahrenheit are used in the U.S. to measure temperatures in most non-scientific contexts. The Rankine scale of absolute temperature also saw some use in thermodynamics . Scientists worldwide use the kelvin and degree Celsius . Several U.S. technical standards are expressed in Fahrenheit temperatures, and some American medical practitioners use degrees Fahrenheit for body temperature. The relationship between
1010-429: A length of 1 / 600 of a stadion , one stadion being about 181.2 m (594 ft); therefore a foot was, at the time, about 302 mm (11.9 in). Its exact size varied from city to city and could range between 270 mm (10.6 in) and 350 mm (13.8 in), but lengths used for temple construction appear to have been about 295 mm (11.6 in) to 325 mm (12.8 in);
1111-618: A measurement of the previous Indian standard of the yard. However, it is now obsolete as the current National Topographic Database of the Survey of India is based on the metric WGS-84 datum , which is also used by the Global Positioning System . An ISO 2848 measure of 3 basic modules (30 cm) is called a " metric foot ", but there were earlier distinct definitions of a metric foot during metrication in France and Germany. In 1799
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#17328691255201212-415: A pound and a quarter ( 20 oz ). There are varying standards for barrel for some specific commodities, including 31 gallons for beer, 40 gallons for whiskey or kerosene, and 42 gallons for petroleum. The general standard for liquids is 31.5 gal or half a hogshead. The common 55-gallon size of drum for storing and transporting various products and wastes is sometimes confused with a barrel, though it
1313-424: A quantity may be described as multiples of that of a familiar entity, which can be easier to contextualize than a value in a formal unit system. For instance, a publication may describe an area in a foreign country as a number of multiples of the area of a region local to the readership. The propensity for certain concepts to be used frequently can give rise to loosely defined "systems" of units. For most quantities
1414-496: A result, units of measure could vary not only from location to location but from person to person. Units not based on the human body could be based on agriculture, as is the case with the furlong and the acre , both based on the amount of land able to be worked by a team of oxen . Metric systems of units have evolved since the adoption of the original metric system in France in 1791. The current international standard metric system
1515-464: A small parcel, but becomes significant for mapping, or when the state plane coordinate system (SPCS) is used in the US, because the origin of the system may be hundreds of thousands of feet (hundreds of miles) from the point of interest. Hence the previous definitions continued to be used for surveying in the United States and India for many years, and are denoted survey feet to distinguish them from
1616-400: A small set of units is required. These units are taken as the base units and the other units are derived units . Thus base units are the units of the quantities which are independent of other quantities and they are the units of length, mass, time, electric current, temperature, luminous intensity and the amount of substance. Derived units are the units of the quantities which are derived from
1717-501: A system which had evolved over the millennia before American independence , and which had its roots in both Roman and Anglo-Saxon units. The customary system was championed by the U.S.-based International Institute for Preserving and Perfecting Weights and Measures in the late 19th century. Some advocates of the customary system saw the French Revolutionary, or metric, system as atheistic. The president of an Ohio auxiliary of
1818-433: A unit is necessary to communicate values of that physical quantity. For example, conveying to someone a particular length without using some sort of unit is impossible, because a length cannot be described without a reference used to make sense of the value given. But not all quantities require a unit of their own. Using physical laws, units of quantities can be expressed as combinations of units of other quantities. Thus only
1919-406: Is 1 ⁄ 16 of a US pint, 1 ⁄ 32 of a US quart, and 1 ⁄ 128 of a US gallon. The teaspoon, tablespoon, and cup are defined in terms of a fluid ounce as 1 ⁄ 6 , 1 ⁄ 2 , and 8 fluid ounces respectively. The fluid ounce derives its name originally from being the volume of one ounce avoirdupois of water, but in the US it is defined as 1 ⁄ 128 of
2020-449: Is feet . However, the singular form may be used like a plural when it is preceded by a number, as in "he is six foot tall." Historically, the human body has been used to provide the basis for units of length. The foot of an adult European-American male is typically about 15.3% of his height, giving a person of 175 cm (5 ft 9 in) a foot-length of about 268 mm (10.6 in), on average. Archaeologists believe that, in
2121-415: Is based upon calculations from surveys of Phase 1 elements at Stonehenge . They found that the underlying diameters of the stone circles had been consistently laid out using multiples of a base unit amounting to 30 long feet , which they calculated to be 1.056 of a modern international foot (thus 12.672 inches or 0.3219 m). Furthermore, this unit is identifiable in the dimensions of some stone lintels at
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#17328691255202222-485: Is central to the scientific method . A standard system of units facilitates this. Scientific systems of units are a refinement of the concept of weights and measures historically developed for commercial purposes. Science , medicine , and engineering often use larger and smaller units of measurement than those used in everyday life. The judicious selection of the units of measurement can aid researchers in problem solving (see, for example, dimensional analysis ). In
2323-409: Is expressed as the product of a numerical value { Z } (a pure number) and a unit [ Z ]: For example, let Z {\displaystyle Z} be "2 metres"; then, { Z } = 2 {\displaystyle \{Z\}=2} is the numerical value and [ Z ] = m e t r e {\displaystyle [Z]=\mathrm {metre} } is the unit. Conversely,
2424-400: Is legally defined as a measure of mass , but the name pound is also applied to measures of force . For instance, in many contexts, the pound avoirdupois is used as a unit of mass, but in some contexts, the term "pound" is used to refer to " pound-force ". The slug is another unit of mass derived from pound-force. Troy weight, avoirdupois weight, and apothecaries' weight are all built from
2525-501: Is no traditional customary unit, international units are used, sometimes mixed with customary units: for example, electrical resistance of wire expressed in ohms (SI) per thousand feet. The United States system of units of 1832 is based on the system in use in Britain prior to the introduction to the British imperial system on January 1, 1826. Both systems are derived from English units ,
2626-454: Is not a standard measure. In the U.S., single servings of beverages are usually measured in fluid ounces. Milk is usually sold in half-pints (8 fluid ounces), pints, quarts, half gallons, and gallons. Water volume for sinks, bathtubs, ponds, swimming pools, etc., is usually stated in gallons or cubic feet. Quantities of gases are usually given in cubic feet (at one atmosphere). Minims, drams, gill, and pottle are rarely used currently. The gill
2727-419: Is now defined as exactly 0.0254 m , and the US and imperial avoirdupois pound is now defined as exactly 0.453 592 37 kg . While the above systems of units are based on arbitrary unit values, formalised as standards, natural units in physics are based on physical principle or are selected to make physical equations easier to work with. For example, atomic units (au) were designed to simplify
2828-467: Is of no practical significance given the precision of normal surveying measurements over short distances (usually much less than a mile). Out of 50 states and six other jurisdictions, 40 have legislated that surveying measures should be based on the US survey foot, six have legislated that they be made on the basis of the international foot, and ten have not specified. The Indian survey foot is defined as exactly 0.304 7996 m , presumably derived from
2929-673: Is often referred to as a "half-cup". The pottle is often referred to as a "half-gallon". Dry volume is measured on a separate system, although many of the names remain the same. Small fruits and vegetables are often sold in dry pints and dry quarts. The US dry gallon is less commonly used, and was not included in the handbook that many states recognize as the authority on measurement law. However pecks , or bushels are sometimes used—particularly for grapes , apples and similar fruits in agricultural regions. There have historically been five different English systems of mass: tower , apothecaries' , troy , avoirdupois , and metric . Of these,
3030-400: Is one group of units for measuring volumes of liquids (based on the wine gallon and subdivisions of the fluid ounce ), and one for measuring volumes of dry material , each with their own names and sub-units. Although the units and their names are similar to the units in the imperial system , and many units are shared between the two systems as a whole; with respect to volume, however, this
3131-463: Is quite the contrary. The independence of the U.S. from the British Empire decades prior to the reformation of units in 1824—most notably the gallon , its subdivisions, and (in mass) higher combinations above the pound —is the cause of the differences in values. As a non-participant in that reform, the U.S. retained the separate systems for measuring the volumes of liquids and dry material, whereas
United States customary units - Misplaced Pages Continue
3232-469: Is tasked with ensuring worldwide uniformity of measurements and their traceability to the International System of Units (SI). Metrology is the science of developing nationally and internationally accepted units of measurement. In physics and metrology, units are standards for measurement of physical quantities that need clear definitions to be useful. Reproducibility of experimental results
3333-480: Is the International System of Units (abbreviated to SI). An important feature of modern systems is standardization . Each unit has a universally recognized size. Both the imperial units and US customary units derive from earlier English units . Imperial units were mostly used in the British Commonwealth and the former British Empire . US customary units are still the main system of measurement used in
3434-503: Is the conversion of the unit of measurement in which a quantity is expressed, typically through a multiplicative conversion factor that changes the unit without changing the quantity. This is also often loosely taken to include replacement of a quantity with a corresponding quantity that describes the same physical property. One example of the importance of agreed units is the failure of the NASA Mars Climate Orbiter , which
3535-478: Is the only industrialized country that uses the (international) foot in preference to the meter in its commercial, engineering, and standards activities. The foot is legally recognized in the United Kingdom; road distance signs must use imperial units (however, distances on road signs are always marked in miles or yards, not feet; bridge clearances are given in meters as well as feet and inches), while its usage
3636-574: Is widespread among the British public as a measurement of height. The foot is recognized as an alternative expression of length in Canada. Both the UK and Canada have partially metricated their units of measurement. The measurement of altitude in international aviation (the flight level unit) is one of the few areas where the foot is used outside the English-speaking world. The most common plural of foot
3737-481: The toise and in particular the toise de l'Écritoire , the distance between the fingertips of the outstretched arms of a man. The toise has 6 pieds (feet) each of 326.6 mm (12.9 in). He was unsuccessful in introducing a standard unit of length throughout his realm: an analysis of the measurements of Charlieu Abbey shows that during the 9th century the Roman foot of 296.1 mm (11.66 in)
3838-856: The 4th and 3rd millennia BC among the ancient peoples of Mesopotamia , Egypt and the Indus Valley , and perhaps also Elam in Persia as well. Weights and measures are mentioned in the Bible (Leviticus 19:35–36). It is a commandment to be honest and have fair measures. In the Magna Carta of 1215 (The Great Charter) with the seal of King John , put before him by the Barons of England, King John agreed in Clause 35 "There shall be one measure of wine throughout our whole realm, and one measure of ale and one measure of corn—namely,
3939-782: The Belgic Celts during their invasions prior to the Romans or by the Anglo-Saxons in the 5th and 6th century. Roman units were introduced following their invasion in AD ;43. Following the Roman withdrawal and Saxon invasions , the Roman foot continued to be used in the construction crafts while the Belgic foot was used for land measurement. Both the Welsh and Belgic feet seem to have been based on multiples of
4040-515: The British Standards Institution 's adoption of a scientific standard inch of 25.4 millimeters in 1930. The IEEE standard symbol for a foot is "ft". In some cases, the foot is denoted by a prime , often approximated by an apostrophe , and the inch by a double prime; for example, 2 feet 4 inches is sometimes denoted 2′ 4″. In Imperial units , the foot was defined as 1 / 3 yard, with
4141-663: The Confederation of the Rhine was founded and three different reformed feet were defined, all of which were based on the metric system: Prior to the introduction of the metric system, many European cities and countries used the foot, but it varied considerably in length: the voet in Ypres , Belgium, was 273.8 millimeters (10.78 in) while the piede in Venice was 347.73 millimeters (13.690 in). Lists of conversion factors between
United States customary units - Misplaced Pages Continue
4242-607: The National Institute of Standards and Technology , the National Geodetic Survey , and the United States Department of Commerce deprecated use of the US survey foot and recommended conversion to either the meter or the international foot (0.3048 m). However, the historic relevance of the US survey foot persists, as the Federal Register notes: The date of December 31, 2022, was selected to accompany
4343-548: The Secretary of Commerce "to charter an Interagency Council on Metric Policy ('ICMP'), which will assist the Secretary in coordinating Federal Government-wide implementation of this order." U.S. customary units are widely used on consumer products and in industrial manufacturing. Metric units are standard in science, medicine, as well as many sectors of industry and government, including the military . There are anecdotal objections to
4444-422: The United States outside of science, medicine, many sectors of industry, and some of government and military, and despite Congress having legally authorised metric measure on 28 July 1866. Some steps towards US metrication have been made, particularly the redefinition of basic US and imperial units to derive exactly from SI units. Since the international yard and pound agreement of 1959 the US and imperial inch
4545-506: The barleycorn , but by as early as 950 the English kings seem to have (ineffectually) ordered measures to be based upon an iron yardstick at Winchester and then London . Henry I was said to have ordered a new standard to be based upon the length of his own arm and, by the c. 1300 Act concerning the Composition of Yards and Perches traditionally credited to Edward I or II ,
4646-492: The international yard and pound agreement of 1959. The United States uses customary units in commercial activities, as well as for personal and social use. In science, medicine, many sectors of industry, and some government and military areas, metric units are used. The International System of Units (SI), the modern form of the metric system , is preferred for many uses by the U.S. National Institute of Standards and Technology (NIST). For newer types of measurement where there
4747-401: The metric system , the imperial system , and United States customary units . Historically many of the systems of measurement which had been in use were to some extent based on the dimensions of the human body. Such units, which may be called anthropic units , include the cubit , based on the length of the forearm; the pace , based on the length of a stride; and the foot and hand . As
4848-553: The social sciences , there are no standard units of measurement. A unit of measurement is a standardized quantity of a physical property, used as a factor to express occurring quantities of that property. Units of measurement were among the earliest tools invented by humans. Primitive societies needed rudimentary measures for many tasks: constructing dwellings of an appropriate size and shape, fashioning clothing, or bartering food or raw materials. The earliest known uniform systems of measurement seem to have all been created sometime in
4949-450: The City of London and Westminster , which codified the statute mile as comprising 5,280 feet. The differences among the various physical standard yards around the world, revealed by increasingly powerful microscopes , eventually led to the 1959 adoption of the international foot defined in terms of the meter. The international yard and pound agreement of July 1959 defined the length of
5050-532: The Greeks and the Romans subdivided the foot into 16 digits , but in later years, the Romans also subdivided the foot into 12 unciae (from which both the English words "inch" and " ounce " are derived). After the fall of the Roman Empire, some Roman traditions were continued but others fell into disuse. In AD 790 Charlemagne attempted to reform the units of measure in his domains. His units of length were based on
5151-603: The Institute wrote that the traditional units were "a just weight and a just measure, which alone are acceptable to the Lord". His organization later went so far as to publish music for a song proclaiming "down with every 'metric' scheme". The U.S. government passed the Metric Conversion Act of 1975, which made the metric system "the preferred system of weights and measures for U.S. trade and commerce". The legislation states that
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#17328691255205252-603: The London quart;—and one width of dyed and russet and hauberk cloths—namely, two ells below the selvage..." As of the 21st century, the International System is predominantly used in the world. There exist other unit systems which are used in many places such as the United States Customary System and the Imperial System. The United States is the only industrialized country that has not yet at least mostly converted to
5353-464: The NSRS where it is used now and in the past [emphasis added]. In other words, to minimize disruption in the use of U.S. survey foot for existing NSRS coordinate systems, the change will apply only to the modernized NSRS. State legislation is also important for determining the conversion factor to be used for everyday land surveying and real estate transactions, although the difference (two parts per million )
5454-404: The U.S. Impacts related to the change to international feet will be minimized if a transition occurs concurrently with others [ sic ] changes in the NSRS. ... The difference in timelines will have no effect on users of the existing NSRS (National Spatial Reference System), because NGS ( NOAA 's National Geodetic Survey) will continue to support the U.S. survey foot for components of
5555-402: The U.S. survey foot, the statute mile can be defined using either definition of the foot, as is the case for all other units listed in this table. However, use of definitions based on the U.S. survey foot should be avoided after December 31, 2022 except for historic and legacy applications." The cubic inch , cubic foot and cubic yard are commonly used for measuring volume. In addition, there
5656-473: The US survey foot, and other units defined in terms of it, have been deprecated since 2023, "except for historic and legacy applications". The most widely used area unit with a name unrelated to any length unit is the acre . The National Institute of Standards and Technology formerly contended that customary area units are defined in terms of the square survey foot, not the square international foot, but from 2023 it states that "although historically defined using
5757-421: The United Kingdom and other countries, is based on avoirdupois, with variations from U.S. customary units larger than a pound. The pound avoirdupois, which forms the basis of the U.S. customary system of mass, is defined as exactly 453.59237 grams by agreement between the U.S., the United Kingdom, and other English-speaking countries in 1959. Other units of mass are defined in terms of it. The avoirdupois pound
5858-428: The above basic units. Sizing systems are used for various items in commerce, several of which are U.S.-specific: The United States Code refers to these units as "traditional systems of weights and measures". Units of measurement A unit of measurement , or unit of measure , is a definite magnitude of a quantity , defined and adopted by convention or by law, that is used as a standard for measurement of
5959-457: The avoirdupois weight is the most common system used in the U.S., although Troy weight is still used to weigh precious metals. Apothecaries' weight—once used by pharmacies—has been largely replaced by metric measurements. Tower weight fell out of use in England (due to legal prohibition in 1527) centuries ago, and was never used in the U.S. The imperial system, which is still used for some measures in
6060-414: The base quantities and some of the derived units are the units of speed, work, acceleration, energy, pressure etc. Different systems of units are based on different choices of a set of related units including fundamental and derived units. Following ISO 80000-1 , any value or magnitude of a physical quantity is expressed as a comparison to a unit of that quantity. The value of a physical quantity Z
6161-500: The crew confusing tower instructions (in metres) and altimeter readings (in feet). Three crew and five people on the ground were killed. Thirty-seven were injured. In 1983, a Boeing 767 (which thanks to its pilot's gliding skills landed safely and became known as the Gimli Glider ) ran out of fuel in mid-flight because of two mistakes in figuring the fuel supply of Air Canada 's first aircraft to use metric measurements. This accident
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#17328691255206262-513: The definition of the foot in the Mendenhall Order of 1893, that is 1 ft = 1200 ⁄ 3937 m : this definition was retained for data derived from NAD27, but renamed the US survey foot to distinguish it from the international foot. For most applications, the difference between the two definitions is insignificant – one international foot is exactly 0.999 998 of a US survey foot, for
6363-468: The different systems include the centimetre–gram–second , foot–pound–second , metre–kilogram–second systems, and the International System of Units , SI. Among the different systems of units used in the world, the most widely used and internationally accepted one is SI. The base SI units are the second, metre, kilogram, ampere, kelvin, mole and candela; all other SI units are derived from these base units. Systems of measurement in modern use include
6464-1038: The different temperature scales is linear but the scales have different zero points, so conversion is not simply multiplication by a factor. Pure water freezes at 32 °F = 0 °C and boils at 212 °F = 100 °C at 1 atm . The conversion formula is: { T } ∘ F = 9 5 { T } ∘ C + 32 {\displaystyle \{T\}_{\mathrm {^{\circ }F} }={\tfrac {9}{5}}\{T\}_{\mathrm {^{\circ }C} }+32} or inversely as { T } ∘ C = 5 9 ( { T } ∘ F − 32 ) . {\displaystyle \{T\}_{\mathrm {^{\circ }C} }={\tfrac {5}{9}}{\bigl (}\{T\}_{\mathrm {^{\circ }F} }-32{\bigr )}.} Length Volume Mass Force Energy Power Pressure Torque Insulation Various combination units are in common use; these are straightforwardly defined based on
6565-465: The door of a church on a Sunday and bid 16 men to stop, tall ones and small ones, as they happen to pass out when the service is finished; then make them put their left feet one behind the other, and the length thus obtained shall be a right and lawful rood to measure and survey the land with, and the 16th part of it shall be the right and lawful foot. The Neolithic long foot , first proposed by archeologists Mike Parker Pearson and Andrew Chamberlain,
6666-484: The federal government has a responsibility to assist industry as it voluntarily converts to the metric system, i.e., metrification . This is most evident in U.S. labeling requirements on food products, where SI units are almost always presented alongside customary units. According to the CIA World Factbook , the United States is one of three nations (along with Liberia and Myanmar (Burma) ) that have not adopted
6767-514: The foot is defined as equal to exactly 0.3048 meters. Historically, the "foot" was a part of many local systems of units, including the Greek , Roman , Chinese , French , and English systems. It varied in length from country to country, from city to city, and sometimes from trade to trade. Its length was usually between 250 mm and 335 mm and was generally, but not always, subdivided into 12 inches or 16 digits . The United States
6868-569: The foot to use to the individual states (and other jurisdictions). All SPCS 1983 systems are defined in meters, but forty jurisdictions also use the survey foot, six use the international foot, and ten do not specify which, if any, foot type should be used. In 2019, the NIST, working with the National Geodetic Survey (NGS), National Ocean Service (NOS), National Oceanic and Atmospheric Administration (NOAA) and Department of Commerce (DOC), issued
6969-425: The former was close to the size of the Roman foot. The standard Roman foot ( pes ) was normally about 295.7 mm (11.6 in) (97% of today's measurement), but in some provinces, particularly Germania Inferior , the so-called pes Drusianus (foot of Nero Claudius Drusus ) was sometimes used, with a length of about 334 mm (13.1 in). (In reality, this foot predated Drusus.) Originally both
7070-414: The grain and ounce (apothecaries' has scruple and dram , troy has pennyweight , and avoirdupois has just dram, sometimes spelled drachm ). The dram in avoirdupois weighs just under half of the dram in apothecaries'. The fluid dram unit of volume is based on the weight of 1 dram of water in the apothecaries' system. To alleviate confusion, it is typical when publishing non-avoirdupois weights to mention
7171-481: 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
7272-436: The imperial system had unified the units for both under a new imperial gallon. The U.S. uses the pre-1824 gallon (231 cubic inches, 3,790 cm) and Winchester bushel (2,150.42 cubic inches, 35,239.1 cm), as opposed to British 1824 definition of 1 imperial gallon (4.5 L; 1.2 US gal) = 10 lb (4.5 kg) of water and the bushel as 8 imperial gallons (36 L; 9.6 US gal). One US fluid ounce
7373-474: The imperial system is identical to that in the U.S. customary system. In the U.S., only the ounce, pound and short ton – known in the country simply as the ton – are commonly used, though the hundredweight is still used in agriculture and shipping. The grain is used to describe the mass of propellant and projectiles in small arms ammunition . It was also used to measure medicine and other very small masses. In agricultural practice,
7474-457: The international foot. The United Kingdom was unaffected by this problem, as the retriangulation of Great Britain (1936–62) had been done in meters. In the United States, the foot was defined as 12 inches, with the inch being defined by the Mendenhall Order of 1893 via 39.37 inches = 1 m (making a US foot exactly 1200 / 3937 meters, approximately 0.304 800 61 m ). On December 31, 2022,
7575-501: The international yard for all purposes through the Weights and Measures Act 1963 , effective January 1, 1964. When the international foot was defined in 1959, a great deal of survey data was already available based on the former definitions, especially in the United States and in India . The small difference between the survey foot and the international foot would not be detectable on a survey of
7676-509: The international yard in the United States and countries of the Commonwealth of Nations as exactly 0.9144 meters . Consequently, since a foot is one third of a yard, the international foot is defined to be equal to exactly 0.3048 meters. This was 2 ppm shorter than the previous US definition and 1.7 ppm longer than the previous British definition. The 1959 agreement concluded a series of step-by-step events, set off in particular by
7777-414: The meter became the official unit of length in France . This was not fully enforced, and in 1812 Napoleon introduced the system of mesures usuelles which restored the traditional French measurements in the retail trade, but redefined them in terms of metric units. The foot, or pied métrique , was defined as one third of a meter. This unit continued in use until 1837. In southwestern Germany in 1806,
7878-599: The metric system as their official system of weights and measures. Executive Order 12770 , signed by President George H. W. Bush on July 25, 1991, citing the Metric Conversion Act, directed departments and agencies within the executive branch of the United States Government to "take all appropriate measures within their authority" to use the metric system "as the preferred system of weights and measures for United States trade and commerce" and authorized
7979-559: The metric system. The systematic effort to develop a universally acceptable system of units dates back to 1790 when the French National Assembly charged the French Academy of Sciences to come up such a unit system. This system was the precursor to the metric system which was quickly developed in France but did not take on universal acceptance until 1875 when The Metric Convention Treaty was signed by 17 nations. After this treaty
8080-484: The modernization of the National Spatial Reference System (NSRS) by NOAA 's National Geodetic Survey (NGS). The reason for associating the deprecation of the U.S. survey foot with the modernization of the NSRS is that the biggest impact of the uniform adoption of the international foot will be for users of the NSRS, due to very large coordinate values currently given in U.S. survey feet in many areas of
8181-414: The name of the system along with the unit. Precious metals, for example, are often weighed in "troy ounces", because just "ounce" would be more likely to be assumed to mean an avoirdupois ounce. For the pound and smaller units, the U.S. customary system and the British imperial system are identical. However, they differ when dealing with units larger than the pound. The definition of the pound avoirdupois in
8282-425: The numerical value expressed in an arbitrary unit can be obtained as: Units can only be added or subtracted if they are the same type; however units can always be multiplied or divided, as George Gamow used to explain. Let Z {\displaystyle Z} be "2 metres" and W {\displaystyle W} "3 seconds", then There are certain rules that apply to units: Conversion of units
8383-620: The past, the people of Egypt , India , and Mesopotamia preferred the cubit , while the people of Rome , Greece , and China preferred the foot. Under the Harappan linear measures, Indus cities during the Bronze Age used a foot of 13.2 inches (335 mm) and a cubit of 20.8 inches (528 mm). The Egyptian equivalent of the foot—a measure of four palms or 16 digits—was known as the djeser and has been reconstructed as about 30 cm (11.8 in). The Greek foot ( πούς , pous ) had
8484-497: The same kind of quantity . Any other quantity of that kind can be expressed as a multiple of the unit of measurement. For example, a length is a physical quantity . The metre (symbol m) is a unit of length that represents a definite predetermined length. For instance, when referencing "10 metres" (or 10 m), what is actually meant is 10 times the definite predetermined length called "metre". The definition, agreement, and practical use of units of measurement have played
8585-511: The same basic unit, the grain, which is the same in all three systems. However, while each system has some overlap in the names of their units of measure (all have ounces and pounds), the relationship between the grain and these other units within each system varies. For example, in apothecary and troy weight, the pound and ounce are the same, but are different from the pound and ounce in avoirdupois in terms of their relationships to grains and to each other. The systems also have different units between
8686-434: The same unit for the distance between two cities and the length of a needle. Thus, historically they would develop independently. One way to make large numbers or small fractions easier to read, is to use unit prefixes . At some point in time though, the need to relate the two units might arise, and consequently the need to choose one unit as defining the other or vice versa. For example, an inch could be defined in terms of
8787-511: The site and in the diameter of the "southern circle" at nearby Durrington Walls . Evidence that this unit was in widespread use across southern Britain is available from the Folkton Drums from Yorkshire ( neolithic artifacts, made from chalk, with circumferences that exactly divide as integers into ten long feet) and a similar object, the Lavant drum , excavated at Lavant , Sussex, again with
8888-632: The size of the degree and for the circumference of the Earth was therefore about 25% too small. Historical Legal Metric information Foot (unit) The foot (standard symbol: ft ) is a unit of length in the British imperial and United States customary systems of measurement . The prime symbol , ′ , is commonly used to represent the foot. In both customary and imperial units, one foot comprises 12 inches , and one yard comprises three feet. Since an international agreement in 1959 ,
8989-413: The statute foot was a different measure, exactly 10 / 11 of the old (Belgic) foot. The barleycorn , inch , ell , and yard were likewise shrunk, while rods and furlongs remained the same. The ambiguity over the state of the mile was resolved by the 1593 Act against Converting of Great Houses into Several Tenements and for Restraint of Inmates and Inclosures in and near about
9090-647: The units of length have been defined on the basis of 1 yd = 0.9144 m . The U.S., the United Kingdom and other Commonwealth countries agreed on this definition per the International Yard and Pound Agreement of 1958. At the time of the agreement, the basic geodetic datum in North America was the North American Datum of 1927 (NAD27), which had been constructed by triangulation based on
9191-434: The use of metric units in carpentry and the building trades, on the basis that it is easier to remember an integer number of inches plus a fraction than a measurement in millimeters, or that foot-inch measurements are more suitable when distances are frequently divided into halves, thirds, and quarters, often in parallel. The metric system also lacks a parallel measurement to the foot . The term "United States customary units"
9292-408: The various feet in this list ceased to be used when the countries adopted the metric system. The Netherlands and modern Belgium adopted the metric system in 1817, having used the mesures usuelles under Napoleon and the newly formed German Empire adopted the metric system in 1871. The palm (typically 200–280 mm, ie. 7 7 / 8 to 11 1 / 32 inches)
9393-598: The various units of measure were given in many European reference works including: Many of these standards were peculiar to a particular city, especially in Germany (which, before German unification in 1871, consisted of many kingdoms, principalities, free cities and so on). In many cases the length of the unit was not uniquely fixed: for example, the English foot was stated as 11 pouces 2.6 lignes ( French inches and lines ) by Picard , 11 pouces 3.11 lignes by Maskelyne , and 11 pouces 3 lignes by D'Alembert . Most of
9494-515: The wave equation in atomic physics . Some unusual and non-standard units may be encountered in sciences. These may include the solar mass ( 2 × 10 kg ), the megaton (the energy released by detonating one million tons of trinitrotoluene , TNT) and the electronvolt . To reduce the incidence of retail fraud, many national statutes have standard definitions of weights and measures that may be used (hence " statute measure "), and these are verified by legal officers. In informal settings,
9595-502: The yard being realized as a physical standard (separate from the standard meter). The yard standards of the different Commonwealth countries were periodically compared with one another. The value of the United Kingdom primary standard of the yard was determined in terms of the meter by the National Physical Laboratory in 1964 to be 0.914 3969 m , implying a pre-1959 UK foot of 0.304 7990 m . The UK adopted
9696-453: Was accidentally destroyed on a mission to Mars in September 1999 (instead of entering orbit) due to miscommunications about the value of forces: different computer programs used different units of measurement ( newton versus pound force ). Considerable amounts of effort, time, and money were wasted. On 15 April 1999, Korean Air cargo flight 6316 from Shanghai to Seoul was lost due to
9797-519: Was signed, a General Conference of Weights and Measures (CGPM) was established. The CGPM produced the current SI, which was adopted in 1954 at the 10th Conference of Weights and Measures. Currently, the United States is a dual-system society which uses both the SI and the US Customary system. The use of a single unit of measurement for some quantity has obvious drawbacks. For example, it is impractical to use
9898-549: Was the result of both confusion due to the simultaneous use of metric and Imperial measures and confusion of mass and volume measures. When planning his journey across the Atlantic Ocean in the 1480s, Columbus mistakenly assumed that the mile referred to in the Arabic estimate of 56 + 2 / 3 miles for the size of a degree was the same as the actually much shorter Italian mile of 1,480 metres. His estimate for
9999-436: Was used by the former United States National Bureau of Standards , although "English units" is sometimes used in colloquial speech. For measuring length, the U.S. customary system uses the inch , foot , yard , and mile , which are the only four customary length measurements in everyday use. From 1893, the foot was legally defined as exactly 1200 ⁄ 3937 m (approximately 0.304 8006 m ). Since July 1, 1959,
10100-1381: Was used in many Mediterranean cities instead of the foot. Horace Doursther, whose reference was published in Belgium which had the smallest foot measurements, grouped both units together, while J. F. G. Palaiseau devoted three chapters to units of length: one for linear measures (palms and feet); one for cloth measures (ells); and one for distances traveled (miles and leagues). In Belgium, the words pied (French) and voet (Dutch) would have been used interchangeably. International Standards Organisation (ISO)-defined intermodal containers for efficient global freight/cargo shipping, were defined using feet rather than meters for their leading outside (corner) dimensions. All ISO-standard containers to this day are eight feet wide, and their outer heights and lengths are also primarily defined in, or derived from feet. Quantities of global shipping containers are still primarily counted in Twenty-foot Equivalent Units , or TEUs. Everyday global (civilian) air traffic / aviation continues to be controlled in flight levels (flying altitudes) separated by thousands of feet (although typically read out in hundreds – e.g. flight level 330 actually means 33,000 feet, or about 10 kilometres in altitude). The length of
10201-461: Was used; when it was rebuilt in the 10th century, a foot of about 320 mm (12.6 in) was used. At the same time, monastic buildings used the Carolingian foot of 340 mm (13.4 in). The procedure for verification of the foot as described in the 16th century posthumously published work by Jacob Köbel in his book Geometrei. Von künstlichem Feldmessen und absehen is: Stand at
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