THE UNITED STATES ANDTHE METRIC SYSTEM

A Capsule History

The United States is now the only industrializedcountry in the world that does not use the metricsystem as its predominant system of measurement.

Most Americans think that our involvement withmetric measurement is relatively new. In fact, theUnited States has been increasing its use of metricunits for many years, and the pace has acceleratedin the past three decades. In the early 1800's, theU.S. Coast and Geodetic Survey (thegovernment’s surveying and map-making agency)used meter and kilogram standards brought fromFrance. In 1866, Congress authorized the use ofthe metric system in this country and suppliedeach state with a set of standard metric weightsand measures.

In 1875, the United States solidified itscommitment to the development of theinternationally recognized metric system bybecoming one of the original seventeen signatorynations to the Treaty of the Meter. The signingof this international agreement concluded fiveyears of meetings in which the metric system wasreformulated, refining the accuracy of itsstandards. The Treaty of the Meter, also know asthe “Metric Convention,@ established theInternational Bureau of Weights and Measures(BIPM) in Sèvres, France, to provide standards ofmeasurement for worldwide use.

In 1893, metric standards, developed throughinternational cooperation under the auspices ofBIPM, were adopted as the fundamental standardsfor length and mass in the United States. Ourcustomary measurements -- the foot, pound, quart,etc. -- have been defined in relation to the meterand the kilogram ever since.

The General Conference of Weights andMeasures, the governing body that has overallresponsibility for the metric system, and which ismade up of the signatory nations to the Treaty ofthe Meter, approved an updated version of themetric system in 1960. This modern system iscalled Le Système International d'Unités or theInternational System of Units, abbreviated SI.

The United Kingdom, began a transition to themetric system in 1965 to more fully mesh itsbusiness and trade practices with those of theEuropean Common Market. The conversion ofthe United Kingdom and the Commonwealthnations to SI created a new sense of urgencyregarding the use of metric units in the UnitedStates.

In 1968, Congress authorized a three-year studyof systems of measurement in the U.S., withparticular emphasis on the feasibility of adoptingSI. The detailed U.S. Metric Study wasconducted by the Department of Commerce. A45-member advisory panel consulted with andtook testimony from hundreds of consumers,business organizations, labor groups,manufacturers, and state and local officials.

The final report of the study, “A MetricAmerica: A Decision Whose Time Has Come,”concluded that the U.S. would eventually join therest of the world in the use of the metric system ofmeasurement. The study found that measurementin the United States was already based on metricunits in many areas and that it was becomingmore so every day. The majority of studyparticipants believed that conversion to the metricsystem was in the best interests of the Nation,particularly in view of the importance of foreigntrade and the increasing influence of technologyin American life.

The study recommended that the United Statesimplement a carefully planned transition topredominant use of the metric system over a ten-year period. Congress passed the MetricConversion Act of 1975 “to coordinate and planthe increasing use of the metric system in the UnitedStates.” The Act, however, did not require a ten-year conversion period. A process of voluntaryconversion was initiated, and the U.S. Metric Boardwas established. The Board was charged with“devising and carrying out a broad program ofplanning, coordination, and public education,consistent with other national policy and interests,with the aim of implementing the policy set forth inthis Act.” The efforts of the Metric Board werelargely ignored by the American public, and, in1981, the Board reported to Congress that it lackedthe clear Congressional mandate necessary to bringabout national conversion. Due to this apparentineffectiveness, and in an effort to reduce Federalspending, the Metric Board was disestablished inthe fall of 1982.

The Board’s demise increased doubts about theUnited States’ commitment to metrication. Publicand private sector metric transition slowed at thesame time that the very reasons for the UnitedStates to adopt the metric system -- the increasingcompetitiveness of other nations and the demands ofglobal marketplaces -- made completing theconversion even more important.

Congress, recognizing the necessity of the UnitedStates’ conformance with international standards fortrade, included new encouragement for U.S.industrial metrication in the Omnibus Trade andCompetitiveness Act of 1988. This legislationamended the Metric Conversion Act of 1975 anddesignates the metric system as the Apreferredsystem of weights and measures for United Statestrade and commerce.” The legislation states that theFederal Government has a responsibility to assistindustry, especially small business, as it voluntarilyconverts to the metric system of measurement.

Federal agencies were required by this legislation,with certain exceptions, to use the metric system intheir procurement, grants and other business-relatedactivities by the end of 1992. While not mandatingmetric use in the private sector, the FederalGovernment has sought to serve as a catalyst in themetric conversion of the country’s trade, industry,and commerce.

The current effort toward national metrication isbased on the conclusion that industrial andcommercial productivity, mathematics and scienceeducation, and the competitiveness of Americanproducts and services in world markets, will beenhanced by completing the change to the metricsystem of units. Failure to complete the changewill increasingly handicap the Nation’s industryand economy.

Questions and AnswerQ. What is the metric system?

A. The metric system is a decimal-basedsystem of measurement units. Unitsfor a given quantity, such as length ormass, are related by factors of 10. Calculations involve the simpleprocess of moving the decimal point tothe right or to the left. This modernsystem is called Le SystèmeInternational d'Unités or theInternational System of Units,abbreviated SI.

Q. Is the metric system hard to learn anduse?

A. No. In everyday usage, the mostcommon metric units are the meter (m)to measure length, the second (s) tomeasure time, the kilogram (kg) formass (or weight*), the liter (L) forvolume, and the degree Celsius (EC)for temperature. The metric systemavoids confusing dual-use of terms,such as the inch-pound system’s use ofounces to measure both weight andvolume. The metric system alsoavoids the use of multiple units for thesame quantity; for instance, the inch-pound system’s multiple units forvolume include teaspoons,tablespoons, fluid ounces, cups, pints,quarts, and gallons.

*In commercial and everyday use, the term “weight”may be used as a synonym of mass. Weight isactually the force with which a body is attractedtoward the earth because of gravity.

Q. Will “thinking metric” be difficult?

A. Not really. For example, “thinkingmetric” for temperature means relatingzero degrees Celsius (0 ˚C) with thefreezing point of water, 20 degreesCelsius (20 ˚C) with room temperature,37 degrees Celsius (37 ˚C) with bodytemperature, and 100 degrees Celsius(100 ˚C) with the boiling points ofwater. One millimeter (1 mm) is aboutthe thickness of a dime, and a centimeter(1 cm) is about the width of a fingernail. Almost everyone easily recognizes oneliter (1 L) and two liter (2 L) sodabottles. The contents of that unopenedone liter soda bottle “weighs”approximately one kilogram (1 kg).

Q. Who decided the United States shouldconvert to the metric system?

A. No one “decided the United Statesshould go metric.” As stated in theamended Metric Conversion Act,continued use of “traditional systems ofweights and measures” is still permitted“in nonbusiness activities.” However,metric system use has becomewidespread throughout our economy. Consumers may be surprised at thenumber of items in everyday use thathave been manufactured in metric unitsfor some time. These items are acceptedwith little difficulty and include photo-graphic equipment, automobiles,computers, pharmaceutical products,wine and distilled spirits, and softdrinks. Also, our scientific and medicalcommunities use metric units almostexclusively.

Q. Is there a deadline for conversion?

A. No deadline has been established. Conversion in the private sector, whileencouraged, is voluntary. The OmnibusTrade & Competitiveness Act of 1988amended the 1975 law to make the metricsystem the “preferred system of weightsand measures for United States trade andcommerce” and charged federal agencieswith converting their activities to themetric system.

Q. What is voluntary conversion?

A. Individuals, groups, and industriesdecide whether or not to convert anddetermine conversion timetablesaccording to their own needs.

Q. Why should the United States convertto the metric system?

A. Since trade and communication withother nations is critical to the health ofour economy, adopting themeasurement system used by 95percent of the world’s population isnot a matter of choice, but a matter ofnecessity for the United States.

Q. Why didn't we convert before?

A. Support for a decimal-basedmeasuring system has existed in theUnited States since the 1700s. However, there was no compellingreason to switch because of ourgeographical isolation and because ourprincipal trading partner, England, didnot use metric units. In time theUnited States became a dominant forcein world trade and was able to imposeits products, manufactured in theirunconventional units, on other nations. Times have changed. We no longeroverwhelmingly dominate world tradeand must recognize the need to “fit”our goods and services into otherstrong markets, including theEuropean Union, the new markets ofEastern Europe, and the expandingmarket of the Pacific Rim. Thesemarkets continually stress theirpreference for products and servicesbased on the metric system ofmeasurement.

Q. What are the advantages of conversionfor U.S. industry?

A. During conversion to the metric system,U.S. companies are able simultaneously tostreamline their operations, eliminateinefficiencies, and reduce theirinventories. Because products destined forboth foreign and domestic markets can bedesigned and manufactured to the same(metric) specifications, overlappingproduct lines can be eliminated. Thestandardization of fasteners, components,

and sub-assemblies increases the efficiencyand productivity of all manufacturingprocesses. When firms convert fully to themetric system, they are often surprised todiscover how much the conversion hasincreased their profits. “Converted” firmsfrequently report finding new customers fortheir new metric products and services.

Q. What are the educational benefits ofcompleting the U.S. transition to themetric system?

A. A population that is highly skilled inmath and science is essential for nationaleconomic and social progress. Bycompleting the U.S. transition to themetric system, education and training inthese key subjects will become muchmore efficient. Currently, huge blocksof time are spent learning thecumbersome inch-pound measurements,including learning to manipulate inch-pound fractions and learning to maketedious conversions between metric andinch-pound units. Much of this time canbe redirected toward more worthwhileendeavors. Opportunities for numerousadditional curriculum improvements willsurface when textbooks are revised toreflect the simpler metric system ofunits. Training at all levels, fromelementary school through graduate-level engineering programs, will benefitfrom this important step forward. Aworkforce that is truly able to “speak”the metric measurement language will bebetter able to excel in the globalmarketplace.

Q. Will conversion be costly?

A. Costs will vary in different sectors of theeconomy. However, in most areas, longterm benefits will be realized and shouldmore than offset any one-timeconversion costs. Many industries areconverting as they develop new productsand as older equipment wears out. Inthis way, conversion costs can be held toa minimum.

Q. What is government doing about metricconversion?

A. All of the major Federal agencies have

established plans and internal taskforces for managing their change to themetric system as called for by theamended Metric Conversion Act and a1991 Presidential Executive Order. The General Services Administrationhas established metric specifications forproducts that it buys for Federalagencies. The Defense Departmentuses metric specifications inprocurement and in activities involvingour allies around the world. Many newNASA projects are being designed andbuilt to metric specifications. Mostdesign and construction of FederalGovernment buildings and facilities isnow being done in metric units. TheCommerce Department's MetricProgram works with the memberagencies of the Interagency Council onMetric Policy to identify and helpremove barriers that may stand in theway of metric conversion in federal andstate/local rules, standards, codes, andregulations.

The Department of Commerce hasstarted to implement several newoutreach initiatives that seek to creategreater understanding and a morefavorable environment for nationalmetrication by gaining broad-basedsupport from industry and the generalpublic. These initiatives include aseries of information and publicawareness campaign.

Q. When should the U.S. transition becompleted?

A. Sooner is better. American remainsdependent upon two systems ofmeasurement -- a situation that isuneconomical, inefficient, andconfusing. Time is of the essencebecause our transition to the metricsystem is not becoming cheaper oreasier. Costs and inconvenience willincrease dramatically for everyone associety continues to grow larger andmore complex. A short-term, nation-wide investment in metric conversionwill eliminate the costs of using twomeasurement systems and will providethe long-term return of an efficientsingle-system metric economy.

mailto:metric_prg@nist.gov

For More Information Contact:Office of Weights andMeasures/Metric ProgramNational Institute of Standards andTechnology100 Bureau Drive, Stop 2000Gaithersburg, MD 20899-2000

Phone:(301) 975-3690FAX: (301-948-1416Email: metric_prg@nist.govURL: http://www.nist.gov/metric

NIST LC1136October 1997Contact info.Revised 5/2002