The United States and the Metric System

THE UNITED STATES AND
THE METRIC SYSTEM

A Capsule History

The United States is now the only industrialized The General Conference of Weights and
country in the world that does not use the metric Measures, the governing body that has overall
system as its predominant system of measurement. responsibility for the metric system, and which is
made up of the signatory nations to the Treaty of
Most Americans think that our involvement with the Meter, approved an updated version of the
metric measurement is relatively new. In fact, the metric system in 1960. This modern system is
United States has been increasing its use of metric called Le Système International d'Unités or the
units for many years, and the pace has accelerated International System of Units, abbreviated SI.
in the past three decades. In the early 1800's, the
U.S. Coast and Geodetic Survey (the The United Kingdom, began a transition to the
government’s surveying and map-making agency) metric system in 1965 to more fully mesh its
used meter and kilogram standards brought from business and trade practices with those of the
France. In 1866, Congress authorized the use of European Common Market. The conversion of
the metric system in this country and supplied the United Kingdom and the Commonwealth
each state with a set of standard metric weights nations to SI created a new sense of urgency
and measures. regarding the use of metric units in the United
States.
In 1875, the United States solidified its
commitment to the development of the In 1968, Congress authorized a three-year study
internationally recognized metric system by of systems of measurement in the U.S., with
becoming one of the original seventeen signatory particular emphasis on the feasibility of adopting
nations to the Treaty of the Meter. The signing SI. The detailed U.S. Metric Study was
of this international agreement concluded five conducted by the Department of Commerce. A
years of meetings in which the metric system was 45-member advisory panel consulted with and
reformulated, refining the accuracy of its took testimony from hundreds of consumers,
standards. The Treaty of the Meter, also know as business organizations, labor groups,
the “Metric Convention,@ established the manufacturers, and state and local officials.
International Bureau of Weights and Measures
(BIPM) in Sèvres, France, to provide standards of The final report of the study, “A Metric
measurement for worldwide use. America: A Decision Whose Time Has Come,”
concluded that the U.S. would eventually join the
In 1893, metric standards, developed through rest of the world in the use of the metric system of
international cooperation under the auspices of measurement. The study found that measurement
BIPM, were adopted as the fundamental standards in the United States was already based on metric
for length and mass in the United States. Our units in many areas and that it was becoming
customary measurements -- the foot, pound, quart, more so every day. The majority of study
etc. -- have been defined in relation to the meter participants believed that conversion to the metric
and the kilogram ever since. system was in the best interests of the Nation,
particularly in view of the importance of foreign
trade and the increasing influence of technology
in American life.

The study recommended that the United States The current effort toward national metrication is
implement a carefully planned transition to based on the conclusion that industrial and
predominant use of the metric system over a ten- commercial productivity, mathematics and science
year period. Congress passed the Metric education, and the competitiveness of American
Conversion Act of 1975 “to coordinate and plan products and services in world markets, will be
the increasing use of the metric system in the United enhanced by completing the change to the metric
States.” The Act, however, did not require a ten- system of units. Failure to complete the change
year conversion period. A process of voluntary will increasingly handicap the Nation’s industry
conversion was initiated, and the U.S. Metric Board and economy.
was established. The Board was charged with
“devising and carrying out a broad program of Questions and Answer
planning, coordination, and public education,
consistent with other national policy and interests, Q. What is the metric system?
with the aim of implementing the policy set forth in
this Act.” The efforts of the Metric Board were A. The metric system is a decimal-based
largely ignored by the American public, and, in system of measurement units. Units
1981, the Board reported to Congress that it lacked for a given quantity, such as length or
the clear Congressional mandate necessary to bring mass, are related by factors of 10.
about national conversion. Due to this apparent Calculations involve the simple
ineffectiveness, and in an effort to reduce Federal process of moving the decimal point to
spending, the Metric Board was disestablished in the right or to the left. This modern
the fall of 1982. system is called Le Système
International d'Unités or the
The Board’s demise increased doubts about the International System of Units,
United States’ commitment to metrication. Public abbreviated SI.
and private sector metric transition slowed at the
same time that the very reasons for the United Q. Is the metric system hard to learn and
States to adopt the metric system -- the increasing use?
competitiveness of other nations and the demands of
global marketplaces -- made completing the A. No. In everyday usage, the most
conversion even more important. common metric units are the meter (m)
to measure length, the second (s) to
Congress, recognizing the necessity of the United measure time, the kilogram (kg) for
States’ conformance with international standards for mass (or weight*), the liter (L) for
trade, included new encouragement for U.S. volume, and the degree Celsius (EC)
industrial metrication in the Omnibus Trade and for temperature. The metric system
Competitiveness Act of 1988. This legislation avoids confusing dual-use of terms,
amended the Metric Conversion Act of 1975 and such as the inch-pound system’s use of
designates the metric system as the Apreferred ounces to measure both weight and
system of weights and measures for United States volume. The metric system also
trade and commerce.” The legislation states that the avoids the use of multiple units for the
Federal Government has a responsibility to assist same quantity; for instance, the inch-
industry, especially small business, as it voluntarily pound system’s multiple units for
converts to the metric system of measurement. volume include teaspoons,
tablespoons, fluid ounces, cups, pints,
Federal agencies were required by this legislation, quarts, and gallons.
with certain exceptions, to use the metric system in
their procurement, grants and other business-related *In commercial and everyday use, the term “weight”
activities by the end of 1992. While not mandating may be used as a synonym of mass. Weight is
metric use in the private sector, the Federal actually the force with which a body is attracted
Government has sought to serve as a catalyst in the toward the earth because of gravity.
metric conversion of the country’s trade, industry,
and commerce.

Q. Will “thinking metric” be difficult? A. Individuals, groups, and industries
decide whether or not to convert and
A. Not really. For example, “thinking determine conversion timetables
metric” for temperature means relating according to their own needs.
zero degrees Celsius (0 ˚C) with the
freezing point of water, 20 degrees Q. Why should the United States convert
Celsius (20 ˚C) with room temperature, to the metric system?
37 degrees Celsius (37 ˚C) with body
temperature, and 100 degrees Celsius A. Since trade and communication with
(100 ˚C) with the boiling points of other nations is critical to the health of
water. One millimeter (1 mm) is about our economy, adopting the
the thickness of a dime, and a centimeter measurement system used by 95
(1 cm) is about the width of a fingernail. percent of the world’s population is
Almost everyone easily recognizes one not a matter of choice, but a matter of
liter (1 L) and two liter (2 L) soda necessity for the United States.
bottles. The contents of that unopened
one liter soda bottle “weighs” Q. Why didn't we convert before?
approximately one kilogram (1 kg).
A. Support for a decimal-based
Q. Who decided the United States should measuring system has existed in the
convert to the metric system? United States since the 1700s.
However, there was no compelling
A. No one “decided the United States reason to switch because of our
should go metric.” As stated in the geographical isolation and because our
amended Metric Conversion Act, principal trading partner, England, did
continued use of “traditional systems of not use metric units. In time the
weights and measures” is still permitted United States became a dominant force
“in nonbusiness activities.” However, in world trade and was able to impose
metric system use has become its products, manufactured in their
widespread throughout our economy. unconventional units, on other nations.
Consumers may be surprised at the Times have changed. We no longer
number of items in everyday use that overwhelmingly dominate world trade
have been manufactured in metric units and must recognize the need to “fit”
for some time. These items are accepted our goods and services into other
with little difficulty and include photo- strong markets, including the
graphic equipment, automobiles, European Union, the new markets of
computers, pharmaceutical products, Eastern Europe, and the expanding
wine and distilled spirits, and soft market of the Pacific Rim. These
drinks. Also, our scientific and medical markets continually stress their
communities use metric units almost preference for products and services
exclusively. based on the metric system of
measurement.
Q. Is there a deadline for conversion?
Q. What are the advantages of conversion
A. No deadline has been established. for U.S. industry?
Conversion in the private sector, while
encouraged, is voluntary. The Omnibus A. During conversion to the metric system,
Trade & Competitiveness Act of 1988 U.S. companies are able simultaneously to
amended the 1975 law to make the metric streamline their operations, eliminate
system the “preferred system of weights inefficiencies, and reduce their
and measures for United States trade and inventories. Because products destined for
commerce” and charged federal agencies both foreign and domestic markets can be
with converting their activities to the designed and manufactured to the same
metric system. (metric) specifications, overlapping
product lines can be eliminated. The
Q. What is voluntary conversion? standardization of fasteners, components,

and sub-assemblies increases the efficiency established plans and internal task
and productivity of all manufacturing forces for managing their change to the
processes. When firms convert fully to the metric system as called for by the
metric system, they are often surprised to amended Metric Conversion Act and a
discover how much the conversion has 1991 Presidential Executive Order.
increased their profits. “Converted” firms The General Services Administration
frequently report finding new customers for has established metric specifications for
their new metric products and services. products that it buys for Federal
agencies. The Defense Department
Q. What are the educational benefits of uses metric specifications in
completing the U.S. transition to the procurement and in activities involving
metric system? our allies around the world. Many new
NASA projects are being designed and
A. A population that is highly skilled in built to metric specifications. Most
math and science is essential for national design and construction of Federal
economic and social progress. By Government buildings and facilities is
completing the U.S. transition to the now being done in metric units. The
metric system, education and training in Commerce Department's Metric
these key subjects will become much Program works with the member
more efficient. Currently, huge blocks agencies of the Interagency Council on
of time are spent learning the Metric Policy to identify and help
cumbersome inch-pound measurements, remove barriers that may stand in the
including learning to manipulate inch- way of metric conversion in federal and
pound fractions and learning to make state/local rules, standards, codes, and
tedious conversions between metric and regulations.
inch-pound units. Much of this time can
be redirected toward more worthwhile The Department of Commerce has
endeavors. Opportunities for numerous started to implement several new
additional curriculum improvements will outreach initiatives that seek to create
surface when textbooks are revised to greater understanding and a more
reflect the simpler metric system of favorable environment for national
units. Training at all levels, from metrication by gaining broad-based
elementary school through graduate- support from industry and the general
level engineering programs, will benefit public. These initiatives include a
from this important step forward. A series of information and public
workforce that is truly able to “speak” awareness campaign.
the metric measurement language will be
better able to excel in the global Q. When should the U.S. transition be
marketplace. completed?

Q. Will conversion be costly? A. Sooner is better. American remains
dependent upon two systems of
A. Costs will vary in different sectors of the measurement -- a situation that is
economy. However, in most areas, long uneconomical, inefficient, and
term benefits will be realized and should confusing. Time is of the essence
more than offset any one-time because our transition to the metric
conversion costs. Many industries are system is not becoming cheaper or
converting as they develop new products easier. Costs and inconvenience will
and as older equipment wears out. In increase dramatically for everyone as
this way, conversion costs can be held to society continues to grow larger and
a minimum. more complex. A short-term, nation-
wide investment in metric conversion
Q. What is government doing about metric will eliminate the costs of using two
conversion? measurement systems and will provide
the long-term return of an efficient
A. All of the major Federal agencies have single-system metric economy.











For More Information Contact:

Office of Weights and
Measures/Metric Program
National Institute of Standards and
Technology
100 Bureau Drive, Stop 2000
Gaithersburg, MD 20899-2000

Phone:(301) 975-3690
FAX: (301-948-1416
Email: [email protected]
URL: http://www.nist.gov/metric

NIST LC1136
October 1997

Contact info.
Revised 5/2002