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10 11 12 13 14 15 National Bureau of Standards

Washington, D. C. 20234

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Washington, D. C.

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. S. DEPARTMENT OF COMMERCE

ational Bureau of Standards NBS Special Publication 365

ashington. D. C. 20234 Revised May 1976 METRIC CONVERSION CARD

Approximate Conversions to Metric Measures

ymbol When Yuu Know Multiply by To Find Symbo LENGTH

CO:

inn inches 2.5 centimeters cm

lit feet 30 centimeters cm

idrd yards 0.9 meters m

' ni miles 1.6 kilometers km AREA

.<n' square inches 6.5 square centimeters cm

2 k¥ square feet 0.09 square meters m"

,d2 square yards 0.8 square meters m*

«ini" square miles 2.6 square kilometers km1

'

acres 0.4 hectares ha MASS (we Rht)

miz

lib

ounces 28 grams g pounds 0.45 kilograms kg

short tons 0.9 metric ton t (2000 lb) VOLUME

;P teaspoons 5 milliliters ml.

'bsp tablespoons 15 milliliters mL

n' cubic inches 16 milliliters mL

1 oz fluid ounces 30 milliliters mL

cups 0.24 liters L

{•It pints 0.47 liters L

: (t quarts 0.95 liters L

;al gallons 3.8 liters L

Vf cubic feet 0.03 cubic meters m

3

A' cubic yards 0.76 cubic meters m

3

U. S. DEPARTMENT OF COMMERCE

National Bureau of Standards NBS Special Publication 365

Washington, D. C. 20234 Revised May 1976 METRIC CONVERSION CARD

Approximate Conversions to Metric Measures

CO:

When You Kn To Find Symbol

CD:

in:

CO:

CM:

TEMPER ATURE I exact)

1 1 \t.i;i

in inches 2.5 centimeters cm

ft feet 30 centimeters cm

yd yards 0.9 meters m

mi miles 1.6 kilometers km AREA

in2 square inches 6.5 square centimeters cm"

ft

2 square feet 0.09 square meters m

J

yd2 square yards 0.8 square meters m

2 mi2 square miles 2.6 square kilometers km2

acres 0.4 hectares ha MASS (weight)

oz ounces 28 grams

lb pounds 0.45 kilograms kg

short tons 0.9 metric ton t (20001b) VOLUME

tsp teaspoons 5 milliliters mL

Tbsp tablespoons 15 milliliters mL

in" cubic inches 16 milliliters mL

fl oz fluid ounces 30 milliliters mL

c cups 0.24 liters L

pt pints 0.47 liters L

qt quarts 0.95 liters L

gal gallons 3.8 liters L

ft" cubic feet 0.03 cubic meters m

3

yd3 cubic yards 0.76 cubic meters m

3

CO

lO:

CO:

CM

degrees Fahrenheit

5 9 (after subtracting 32)

degrees

Celsius °C

120

i—irL

degrees Fahrenheit

TEMPER VTURE (exact) 5 9 (after subtracting 32)

degrees

Celsius

120
COMPARE METRIC AND CUSTOMARY UNITS

Length Volume Weight

Metric Meter Liter Kilogram

Customary Inch

Foot Yard

Rod

Mile

Teaspoon Grain Tablespoon Ounce Cup Pound

Pint Ton Quart

Gallon

Metric Units are in 1 0'

s

1000 millimeters = 100 centimeters 1000 meters = 1 kilometer

1 meter = " yards

I liter = 1.1 quarts

1 kilogram — 2 2 pounds

( s approximate)

COMPARE METRIC AND CUSTOMARY UNITS

Length Volume Mass

Metric Meter Liter

(Weight) Kilogram

Customary Inch

Foot Yard

Rod

Mile

Teaspoon

Tablespoon

Cup

Pint Quart

Gallon

Grain Ounce Pound

Ton

Metric Units ore in 10 s 1000 millimeters = 100 centimeters 1000 meters = 1 kilometer

— | meter

I meter 5 Hi yards

I liter = 1.1 quarts

I kilogram = 2.2 pounds

( s; approximate)

NOTE: Scales on reverse side

are approximate.

Approximate Conversions llom Meti it MeaMireSymbol When You know Multiply by To Find Symbol LENGTH mm millimeters 0.04 inches in cm centimeters 0.4 inches in m meters 33 feet ft

ni meters 1.1 yards yd km kilometers 0.6 miles mi ARE \ cm2 square centimeters 0.16 square inches in

2 m

2 square meters 1.2 square yards yd2 km2 square kilometers 0.4 square miles mi!

ha hectares 2.5 acres (10 000 m

a

> MASS (weight)

g grams 0.035 ounces oz kg kilograms 2.2 pounds 11)

t metric ton 1.1 short tons

( 1000 kg) VOLUME

mL milliliters 0.03 fluid ounces floz mL milliliters 0.06 cubic inches in' L liters 2.1 pints Pt L liters 1.06 quarts qt L liters 0.26 gallons gal m

3 cubic meters 35 cubic feet ft2 m

s cubic meters 1.3 cubic yards yd'

00

TEMPI- Ti Vn'KK i exm t ) °C degrees 9/5 (then degrees °F

Celsius add 32) Fahrenheit For sale by the Superintendent of Documents, U.S. Govern- ment Printing Office, Washington, D.C. 20402. Price -25

cents domestic post-paid; add l/± additional for foreign

mailing. Stock Number 0303-0168. Catalog No. C13.10: 365/2. GPO : 1976 0 - 207-401

U S. DEPARTMENT OF COMMERCE

Notional Bureau of Standards Washington. D C 20234

NBS Special Publication 376

Issued December 1972

For sale by the Superintendent of Documents, U.S. Government Printing

Office, Washington. D C 20402

(Order by SD Catolog No CI 3 10:376).

Price 25 cents.

U S DEPARTMENT OF COMMERCE

National Bureau ol Standards Washington, D.C. 20234

NBS Special Publication 376

Issued January 1979

For sale by the Superintendent of Documents, U.S. Government Printing

Office, Washington, D.C. 20402

Stock No. 003-003-01080-4

Price 60 cents

$9.90 per 100 copies

Approximate Conversions irom Metric Measures

Symbol When You Know, Multiply by To Find Symbol LENGTH mm millimeters 0.04 inches in cm centimeters 0.4 inches in m meters 3.3 feet ft m meters 1.1 yards yd km kilometers 0.6 miles mi AREA

cm2 square centimeters 0.16 square inches in

2 m

2 square meters 1.2 square yards yd2 km2 square kilometers 0.4 square miles mi2

ha hectares 2.5 acres (10 000 m

2

) MASS (weight) g

grams 0.035 ounces oz kg kilograms 2.2 pounds lb

t metric ton 1.1 short tons (1000 kg) VOLUME

mL milliliters 0.03 fluid ounces fl oz mL milliliters 0.06 cubic inches in

2 L liters 2.1 pints Pt L liters 1.06 quarts qt L liters 0.26 gallons gal m

s cubic meters 35 cubic feel ft" m" cubic meters 1.3 cubic yards jrf

CO

°c degTees

Celsius

TEMPERATURE (exact) 9/5 (then degrees °F add 32) Fahrenheit For sale by the Superintendent of Documents, U.S. Govern- ment Printing Office. Washington, D.C. 20402. Price 25

cents domestic post-paid; add additional for foreign mailing. Stock Number 0303-0168. Catalog No. C13.10t 365/2. GPO : 1976 O - 207-401 y
UNITED STATES DEPARTMENT OF COMMERCE

National Bureau of Standards

Washington, D.C. 20234

. riser .

Fellow American:

This Nation is now embarked on a changeover to the metric system of

measurement. When the President signed the Metric Conversion Act,

on December 23, 1975, the United States adopted a policy of encouraging

a voluntary changeover to the metric system of weights and measures.

The material included in this package is designed to help us make that

changeover as easily and painlessly as possible. As you look over these

brochures and charts, you will see that in our everyday lives we will be

dealing with four basic units of measurement: meter, liter, gram and

degree Celsius. All of these units may be equated or 'translated' to

our customary units of measurement: yard, quart, ounce and degree

Fahrenheit. The important thing to remember is that eventually translation will not be necessary, because metric is simply a new language for

communicating measurement information. Thus, it is my hope that this

package will help you learn to 'speak' metric with ease and fluency.

Since its establishment in 1901, the National Bureau of Standards has

promoted accuracy and uniformity in our Nation's measurement system.

The countless measurements made every day in our homes, offices and

factories can be traced ultimately to precision standards maintained by

It has been increasingly evident over the past 30 years that the metric

system is the measurement language preferred by most nations. Recognizing

this fact, the Congress in 1968 asked the National Bureau of Standards to

undertake a comprehensive study of the metric system and make recommendations for national policy. As a result of this NBS study, the Congress

began the legislative process which culminated in the Metric Conversion

Act of 1975.

I am confident that Americans will adapt quickly and easily to the metric

system. This will bring us into closer harmony with the rest of the world

and make it easier for us to do business with other nations.

Sincerely

,

NBS.

Ernest Ambler

Acting Director

/4MRK2IJOINSA

METRICWORLD

"It is therefore declared that the policy of the United States shall

be to coordinate and plan the increasing use of the metric system

in the United States and to establish a United States Metric Board . . ." (Metric Conversion Act of 1975)

ON December 23, 1975, President

Ford signed into law the Metric

Conversion Act, establishing for the

first time a national policy in support

of metric measurement and ending a dilemma that had continued throughout the entire history of the Republic.

George Washington had raised the

issue of a more uniform system of

weights and measures in his first message to Congress on January 8, 1790.

John Adams and Thomas Jefferson

became strong advocates of that idea,

speaking favorably of the recentlydeveloped French metric system.

Instead, the young Nation followed

the tradition inherited from the British, the "customary" system of measurement. In 1875, the United States committed itself to metric by signing an international agreement, the Treaty

of the Meter. This treaty was followed

more in the breach than the observance. Inches, not meters, continued

to reign supreme at home, although one result was that, ever since 1893, our national measurement standards

have been metric.

Now at last, with the signing of the

new law, the dilemma has been re- solved through a national policy of

coordinating the increasing use of

metric in this country on a voluntary

basis. The impetus for such a policy

has come from our business community, which has been gradually adopting metric over the last decade. Our

schools have also begun to emphasize metric, and it is apparent that the

country would have drifted through

metrication in an uncoordinated way

unless action had been taken at the

national level. The Metric Conversion Act of 1975

created a U.S. Metric Board, appointed by the President with the advice and consent of the Senate. The

Board consists of 17 members representing the various economic sectors affected by the metric changeover.

These include engineering, science,

large and small business, organized

labor, education, manufacturing, consumers, weights and measures officials, State and local governments,

and the construction industry.

The Board's function is to devise

and carry out a broad program of

planning, coordination and public

education consistent with other national policies and interests. This legislative action is, in part, the result of

the comprehensive, 3-year study performed by the National Bureau of

Standards for the Secretary of Commerce and submitted to the Congress

in July 1971. This study recommended

that the United States change to the

metric system deliberately and carefully through a coordinated program.

The purpose of the Metric Conversion Act of 1975 is to accomplish this

goal. It allows the development of a

rational plan for a voluntary changeover. In this way, metric will come as the various sectors of our economy

are ready for it—and not before.

In fact, metric has come to many

sectors of American life over the past

several years at an ever accelerating

but erratic pace. Industry continues

to take the lead in the private sector. At least 37 major corporations have

announced policies to convert their

operations. The total sales of these

companies exceed $130 billion, and

the list contains four of the Nation's

10 largest firms. Some of the first metric-minded corporations included:

Caterpillar Tractor, Chrysler, Ford

Motor Company, General Motors,

IBM, International Harvester, Minnesota Mining and Manufacturing, Travelers Insurance, and Xerox.

Whereas until just recently the

metric changeover was found predominately among manufacturers with overseas interests, some of America's

largest retailers have gotten on the

bandwagon. Sears, Roebuck and

Company, Montgomery Ward and

Company, , and J. C. Penney are notable leaders in this category.

As mentioned, another sector of

American life that has seen growing

use of the metric system is education.

School systems in all 50 states have

turn page

Reprinted from DIMENSIONS/NBS February 1 976
February 7976 7
underway some type of metric activity. These activities include: making

metric workshops available to teachers, providing guidelines for training

of teachers, producing educational

television programs, and specifying

the use of metric as the primary

measurement language in new text- book purchases. In more than 30

states this "trend" is reinforced by

State legislation or by State school

board action. In Maryland, for example, the State School Board adopted

a resolution in August 1973, calling

for schools to be totally metric by

1980. The State Department of Education has a well developed plan and

a timetable to meet this objective.

The Congress recognized the

schools' swing to metric in the Education Amendments of 1974, P.L. 93-

380, which authorized a Metric Education Program to be managed by the

U.S. Office of Education. Appropriated funds support model and demonstration projects aimed at improving the quality and extent of metric

education. The Metric Conversion

Act of 1975 also recognizes the need

to train teachers and introduce metric

into the Nation's classrooms. A representative of the educational community is included on the U.S. Metric

Board.

The States are not limiting themselves just to metric education in schools. At the time of the signing of

the bill a total of 13 states had erected

some metric road signs; Georgia,

Maine, and California had established

State metric conversion commissions;

California's Division of Oil and Gas

had switched to using only metric

units; Pennsylvania and Florida had

cooperated with the Sun Oil Company in a pilot test to sell gasoline by

the liter; North Dakota had adopted

metric signs for its State parks; and

bills to coordinate metric conversion

had been introduced into 18 State

legislatures.

State and local weights and measures officials through their organization, the National Conference on

Weights and Measures, have begun

planning for the effects of metric

changeover on commercial weights

and measures activities. Working with

this group, for which the National

Bureau of Standards maintains the

Secretariat, NBS has already equipped

each State with a set of metric standards and laboratory instruments that are NBS-certified as to accuracy.

On the Federal level, various

metrication efforts have been underway to meet immediate needs. Since

publication of the metric study in 1971, NBS has maintained a Metric

Information Office. The volume of

inquiries and requests have grown

steadily. In one 6-month period in 1975, NBS answered 20,000 letters and 2,000 telephone calls for information. More than 100,000 NBS

Metric Kits have been prepared and

are being sold through the Government Printing Office. A national

speakers bureau was formed to meet

a need for metric information from

civic, homemaker, PTA, and other

groups.

The U.S. Metric Board assumes many of NBS' public information

functions, but the Bureau will continue to provide international metric

coordination through the General

Conference on Weights and Measures created by the Treaty of the

Meter. It is at this Conference that

the components of the modernized

metric system, International System of

Units (SI), are agreed upon by the

participating nations. The Bureau

will also retain responsibility for

maintaining the national measure- ment system, coordinating metrication with State weights and measures

officials, and through its interaction

with consumer, business, and scientific groups, assist the nation in the

changeover to metric.

Activity in other Federal agencies

is underway:

• The Department of Defense issued

a policy statement in June 1975 that

it would use metric when feasible,

practical, and efficient. •The Treasury Department, at the

request of industry, has held hearings on new regulations that would

specify metric-sized bottles for distilled alcoholic beverages. There was

no opposition to these regulations at the hearings. Similar regulations have

already been approved for the wine

industry. • The National Aeronautics and Space

Administration has been using metric

units extensively for several years. •The Interagency Committee on

Standards Policy, chaired by the Department of Commerce, has established a Metrication Subcommittee to help coordinate Federal agency

metric activities. • Other Federal agencies which have

initiated some metric activity—-rang- ing from forming committees to us- ing metric publications and signs

include the Department of Interior,

Federal Highway Administration, Federal Housing Administration, Department of Health, Education and Welfare, National Weather Service, Maritime Administration, Forest Service,

National Park Service, Agriculture

Department, Patent and Trademark

Office, Environmental Protection

Agency, and Federal Communications

Commission.

8 DIMENSIONS I NBS
Just why is the United States going

metric after having lived with the

English system for more than 200

years? The answer is quite simple:

We cannot afford not to.

All of our major trading partners

have either gone metric or are in the

process of doing so. In fact, the only

countries still not committed are Brunei, Burma, Liberia, and Yemen.

Before the 1975 Act, we literally were

an island in a metric sea. The British

Commonwealth countries, with whom

we shared the pounds-quarts-yards

system for so long, have all committed themselves to metric. This in- cludes Canada, our closest neighbor,

which has an unofficial goal of being

all-metric by 1980.

Our industrial community has also seen the necessity for metric conversion as markets for American goods

and services expand overseas. In order

to do effective business abroad, these

large corporations have had to dualdimension their products, create a separate production capability to turn out metric products for export, or abandon customary design altogether

and produce all products in metric

dimensions. More and more corporations are doing the latter. We are also seeing some barriers

being erected to U.S. products in customary dimensions. The Common

Market in 1971 adopted a directive

that requires all exporters to the nine

Common Market nations to indicate

the dimensions of their products in metric units by 1978. Dual dimensioning will be allowed only if determined not to be confusing, with each

nation to judge compliance separately. This action could bar American goods from these markets or could lead to costly relabeling of

products.

Ultimately, it is in our national best

interest to convert to metric. And

there is a decided advantage for

American industries that "go metric."

In addition to opening up new

markets, the benefits of standardization under the metric system will be

realized in reduced inventories. Manufacturers will not have to keep on

hand as many product lines to cor- respond with various size requirements. For example, the Treasury Department's new regulations, scheduled to go into effect in 1979, will reduce the number of "standardized"

wine bottles offered in this country

from 16 to seven. The U.S. fastener

industry will replace 59 customary

sizes with 25 metric sizes for threaded

fasteners.

A question frequently asked is what

effect this changeover will have on

the average citizen. Everyone will be

affected, but the disruption in normal

living will be minimal. Experience in other countries suggests that the

American public will have little trouble in mastering the few metric

units it will need for everyday living.

Most persons will need to know

only three measurement units

meters, liters and grams. A meter is a unit of length slightly longer than

a yard; a liter is a measure of volume

and is a little larger than a quart; a gram is a unit of weight about as heavy as a paper clip. Because gram

is such a small unit, it is easier to think about the kilogram (1000

grams), which amounts to a little more than 2 pounds.

Metric is a decimal system that uses multiples of 10, as does our currency

system. Each basic metric unit can be multiplied or divided by factors

of 10 to get larger and smaller units. These multiples and submultiples are indicated by prefixes such as kilo

(one thousand), centi (one hundredth) and milli (one thousandth).

Thus a kilometer means 1000 meters,

a centimeter is 1/100 of a meter and

a millimeter is 1/1000 of a meter.

Temperatures in metric are measured on the Celsius scale rather than

Fahrenheit scale. (Celsius was formerly called Centigrade.) In the

Celsius scale, water boils at 100 degrees and freezes at 0 degrees. This

is easier to remember than in Fahrenheit, where water boils at 212 degrees

and freezes at 32 degrees.

The changeover will create minimal confusion. Initially most items

such as roadsigns and consumer

goods will be labeled in both cus- tomary and metric dimensions. This

is already happening with some automobile speedometers that are dually

labeled. In the supermarket, canned

goods will be labeled in both ounces and grams for a time (many are al- ready) and eventually in grams alone.

The Metric Conversion Act of 1975

and the U.S. Metric Board which that

Act creates will provide the necessary

focal point for a smooth, coordinated

conversion to the metric system in

this country. No one will be forced

to "go metric." But gradually, as each

of our country's economic sectors see

the desirability of going metric in a

rational way, we will become a predominately metric nation.

February 1976 9
Some References on

metric Information

Including a Chart on

HI! Vou need to Know Rbout metric

NBS LC1070

January 1977

Supersedes NBS Special Publication 389

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards
U.S. METRIC STUDY

•I See Page 5 for Ordering Information

The United States joined the worldwide trend toward adoption of the metric system

of measurement with the enactment of the Metric Conversion Act of 1975. Several

years prior to that action, the Congress asked the National Bureau of Standards to

make a thorough investigation of the metric question. That investigation involved

public hearings and surveys of almost every activity of our society—from education

and the consumer to international trade and national security. The findings are given

in the following summary and 12 detailed reports:

A METRIC AMERICA: A DECISION WHOSE TIME HAS COME (Sum- $2.70

mary Report to the Congress). D. V. DeSimone, NBS SP 345, 190 pages

(July 1971), SD Stock No. SN 003-003-00884-2.

INTERNATIONAL STANDARDS. R. D. Huntoon et al., NBS SP345-1, $1.70

145 pages (Dec. 1970), SD Stock No. SN 003-003-00731-5.

FEDERAL GOVERNMENT: CIVILIAN AGENCIES. R. E. Clark and J. M. $3.20

Tascher, NBS SP 345-2, 324 pages (July 1970), SD Stock No. SN 003-

003-00824-9.

COMMERCIAL WEIGHTS AND MEASURES. S. L. Hatos, NBS SP 345-3, $1.75

109 pages (July 1971), SD Stock No. SN 003-003-00859-1.

THE MANUFACTURING INDUSTRY. L. E. Barbrow, Coordinator, NBS $1.95

SP 345-4, 165 pages (July 1971), SD Stock No. SN 003-003-00825-7.

NONMANUFACTURING BUSINESSES. E. D. Bunten and J. R. Cornog, $2.15

NBS SP 345-5, 192 pages (Aug. 1971), SD Stock No. SN 003-003-00898-2.

EDUCATION. B. D. Robinson, NBS SP 345-6, 209 pages (July 1971), $2.30

SD Stock No. SN 003-003-00858-3.

THE CONSUMER. B. D. Rothrock, NBS SP 345-7, 146 pages (July $1.75

1971), SD Stock No. SN 003-003-00864-8.

INTERNATIONAL TRADE. G. F. Gordon, NBS SP 345-8, 181 pages, $2.10

(Aug. 1971), SD Stock No. SN 003-003-00895-8.

U.S. METRIC STUDY INTERIM REPORT: DEPARTMENT OF DEFENSE. $5.50

D.V. DeSimone, NBS SP 345-9, 132 pages (June 1971), (Order as com (from NTIS

71-50305 from the National Technical Information Service, 5285 Port only)

Royal Rd., Springfield, VA. 22151.)

A HISTORY OF THE METRIC CONTROVERSY IN THE UNITED STATES $3.05

C. F. Treat, NBS SP 345-10, 306 pages (Aug. 1971), SD Stock No. SN

003-003-00879-6.

ENGINEERING STANDARDS. R. D. Stiehler, NBS SP 345-11, 257 pages $2.70

(July 1971), SD Stock No. SN 003-003-00835-4.

TESTIMONY OF NATIONALLY REPRESENTATIVE GROUPS. J. V. $2.00

Odom, Editor, NBS SP 345-12, 174 pages (July 1971), SD Stock No. SN

003-003-00865-6.

2
NBS METRIC PUBLICATIONS

•I See Page 5 for Ordering Information

The National Bureau off Standards has compiled six useful items into a single official

metric information kit which is available for sale. Priced items are also sold individually at the prices listed. Ordering information is on the back of this publication.

COMPLETE NBS METRIC KIT, NBS SP 410, SD Stock No. $2.00 per kit

SN 003-003-01736-1. 25% discount for 100 or more

Metric Conversion Card, NBS SP 365, SD Stock No. $4.70 per 100

SN 003-003-1068-5

For Good Measure (ruler), NBS SP 376, SD Stock No. $4.70 per 100

SN 003-003-1080-4.

Brief History of Measurement Systems with Chart of $5.70 per 100

the Modernized Metric System, NBS SP 304A, SD Stock

No. SN 003-003-1713-2.

What About Metric?, NBS CIS 7, SD Stock No. SN $ .35

003-003-1688-8. $23.50 per 100

America Joins the Metric World, Reprinted from DIMENSIONS/ Not sold

NBS (February 1976) separately

NBS Metric Information (bibliography), NBS LC 1070 Not sold

(includes chart "All You Need to Know About Metric") separately

The following are other metric materials published by the National Bureau of Standards.

FACTORS FOR HIGH-PRECISION CONVERSION—U.S. CUSTOMARY See

AND METRIC UNITS. NBS LC 1071, 8 pages (July 1976). page 5

METRIC STYLE GUIDE (for the News Media). NBS LC 1069, 6 pages See

(September 1976). page 5

UNITS AND SYSTEMS OF WEIGHTS AND MEASURES. NBS LC 1035, See

26 pages (1976). page 5

HOUSEHOLD WEIGHTS AND MEASURES. NBS SP 430, 2 pages (1975), $ .25

SD Stock No. SN 003-003-01542-3.

THE INTERNATIONAL SYSTEM OF UNITS (SI). NBS SP 330, 43 pages $ .80

(1974), SD Stock No. SN 003-003-01326-9.

WALL CHART OF THE MODERNIZED METRIC SYSTEM. NBS SP 304, 1 $ .65

page (1972), SD Stock No. SN 003-003-00079-5.

SUCCESSFUL EXPERIENCES IN TEACHING METRIC. NBS SP 441, $2.30

115 pages (1976), SD Stock No. SN 003-003-01568-7.

INTERNATIONAL BUREAU OF WEIGHTS AND MEASURES. NBS SP $3.00

420, 256 pages (1975), SD Stock No. SN 003-003-01408-7.

3

Nil Vdu Will need to Know Hbout metric

(For Vour Euerydny life)

Metric is based on Decimal system

The metric system is simple to learn. For use in your everyday life you

will need to know only ten units, You will also need to get used to a few new temperatures. Of course, there are other units which most

persons will not need to learn. There are even some metric units with which you are already familiar: those for time and electricity are the same as you use now.

BBSIC UniTS

METER: a liltle longer lhan a yard (about 1.1 yards)

LITER: a little larger than a quart (about 1.06 qui CRAM: a little more than the weight of a paper clip

ts)

(comparative sizes

COMMON PREFIXES

(to be used with basic units)

mill): one-thousandth (0.001)

cent): one-hundredth (0.01) kilo: one-thousand times (1000)

For example:

1000 millimeters = 1 meter

100 centimeters = 1 meter

1000 meters = 1 kilometer

OTHER COMMONLY USED UNITS

millimeter: 0.001 meter diameter of paper clip wire

centimeter: 0.01 meter a little more lhan the width of a paper

clip (about 0.4 inch) kilometer: 1000 meters somewhat further than Vx mile (aboutO.6 mile) kilogram: 1000 grams a little more than 2 pounds (about 2.2 pounds)

milliliter: 0.001 liter five of them make a teaspoon

OTHER USEFUL UNITS

hectare: about 2V> acres metric Ion: about one ton 25 DECREES CELSIUS WEATHER UNITS: FOR TEMPERATURE

degrees Celsius FOR PRESSUREkilopastals are used

100 kilopascals = 29.5 inches of Hg 114.5 psil

water freezes

60 9B.6 body tempera

Some References on

metric Information

Including a Chart on mi Voo need to Know About metric

NBSLC 1070 January 1977

Supersedes NBS Special Publication 389

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards
ADDITIONAL SOURCES OF METRIC INFORMATION

See Page 5 for Ordering Information

American National Metric Council, 1625 Massachusetts Ave., NW., Washington, D.C.

20036. Established originally under the auspices of the American National Standards

Institute to provide guidance to industrial and commercial segments of society.

American National Standards Institute (ANSI), 1430 Broadway, New York, N.Y. 10018.

Publishes national standards and metric practice guides.

American Society for Testing and Materials, 1916 Race St., Philadelphia, PA 19103.

Publishes assorted metric aids.

The Department of Defense has reproduced for free distribution two NBS metric items —the Modernized Metric System (wall chart in color) and the Metric Conversion

Card (wallet card)—which are available upon request from your nearest Army school

representative or Army reserve center.

National Council of Teachers of Mathematics, 1906 Association Drive, Reston, VA

22091. Publishes listings of organizations marketing metric material for educators.

National Science Teachers Association, 1201 Sixteenth St., NW., Washington, D.C.

20036. Publishes metric kit for teachers.

Science Service, 1719 N St., NW., Washington, D.C. 20009. Publishes "Things-ofScience" metric kit for students.

U.S. Metric Association, Sugarloaf Star Route, Boulder, CO 80302. Distributes educational material and publishes a quarterly newsletter, which is available to members.

National metric conversion boards in other countries can supply general information about conversion in their respective countries and can also provide referrals to

other organizations therein. Their addresses are listed below.

Metric Conversion Board

18-24 Chandos Street

St. Leonards, N.S.W. 2065 Australia

Metric Advisory Board

P. O. Box 10-243

The Terrace

Wellington, New Zealand

South African Bureau of Standards

Private Bag X191

Pretoria, South Africa

Metrication Board

22 Kingsway

London WG2B 6LE England

Metrication Board of Zambia

P. O. Box 1968

Lusaka, Zambia

Metric Commission

320 Queen Street

Ottawa K1A OH5 Canada

4

U.S. METRIC STUDY HUM See Page 5 (or Ordering Information

The United Stales joined the worldwide trend toward adoption ol the metric system

ol measurement with the enactment of the Metric Conversion Act ol 1975. Several years prior to that action, the Congress asked the National Bureau of Standards to make a thorough Investigation ol the metric question. That investigation involved

public hearings and surveys of almost every activity ol our society—Irom education and the consumer to international trade and national security. The findings are given

In the following summary and 12 detailed reports:

A METRIC AMERICA: A DECISION WHOSE TIME HAS COME (Sum- $2.70 mary Report to the Congress). D. V. DeSlmone, NBS SP 345, 190 pages

(July 1971), SD Stock No. SN 003-003-00884-2. INTERNATIONAL STANDARDS. R. D. Huntoon et al., NBS SP345-1, $1.70 145 pages (Dec. 1970), SD Stock No. SN 003-003-00731-5. FEDERAL GOVERNMENT: CIVILIAN AGENCIES. R. E. Clark and J. M. $3.20 Tascher, NBS SP 345-2, 324 pages (July 1970), SD Stock No. SN 003- 003-00824-9. COMMERCIAL WEIGHTS AND MEASURES. S. L. Hatos, NBS SP 345-3, $1.75 109 pages (July 1971), SD Stock No. SN 003-003-00859-1. THE MANUFACTURING INDUSTRY. L. E. Barbrow, Coordinator, NBS $1.95 SP 345-4, 165 pages (July 1971), SD Stock No. SN 003-003-00825-7. NONMANUFACTURING BUSINESSES. E. D. Bunten and J. R. Cornog, $2.15 NBS SP 345-5, 192 pages (Aug. 1971 ), SD Stock No. SN 003-003-00898-2. EDUCATION. B. D. Robinson, NBS SP 345-6, 209 pages (July 1971 ), $2.30 SD Stock No. SN 003-003-00858-3. THE CONSUMER. B. D. Rothrock, NBS SP 345-7, 146 pages (July $1.75

1971), SD Stock No. SN 003-003-00864-8. INTERNATIONAL TRADE. G. F. Gordon, NBS SP 345-8, 181 pages, $2.10 (Aug. 1971), SD Stock No. SN 003-003-00895-8.

U.S. METRIC STUDY INTERIM REPORT: DEPARTMENT OF DEFENSE. $5.50

D.V. DeSlmone, NBS SP 345-9, 132 pages (June 1971), (Order as com (from NTIS

71-50305 Irom the Notional Technical Information Service, 5285 Port only) Royal Rd., Springfield, VA. 22151.) A HISTORY OF THE METRIC CONTROVERSY IN THE UNITED STATES $3.05

C. F. Treat, NBS SP 345-10, 306 pages (Aug. 1971), SD Stock No. SN

003-003-00879-6. ENGINEERING STANDARDS. R. D. Stiehler, NBS SP 345-1 1. 257 pages $2.70

(July 1971), SD Stock No. SN 003-003-00835-4. TESTIMONY OF NATIONALLY REPRESENTATIVE GROUPS. J. V. $2 00 Odom, Editor, NBS SP 345-12, 174 pages (July 1971), SD Stock No. SN

003-003-00865-6.

NBS METRIC PUBLICATIONS IIIIIM See Page 5 for Ordering Information

The National Bureau ol Standards has compiled six useful items into a single official metric information kit which is available lor sale. Priced items are also sold individ- ually at the prices listed. Ordering information is on the back of this publication. COMPLETE NBS METRIC KIT, NBS SP 410, SD Stock No. $2.00 per kit SN 003-003-01736-1. 25% discount for 100 or more

Metric Conversion Card, NBS SP 365, SD Stock No. $4.70 per 100 SN 003-003-1068-5

For Good Measure (ruler), NBS SP 376, SD Stock No. $4.70 per 100 SN 003-003-1080-4.

Brief History of Measurement Systems with Chart of $5.70 per 100

the Modernized Metric System, NBS SP 304A, SD Stock

No. SN 003-003-1713-2.

What About Metric?, NBS CIS 7, SD Stock No. SN $ .35 003-003-1688-8. $23.50 per 100

America Joins the Metric World, Reprinted from DIMENSIONS/ Not sold NBS (February 1976) separately NBS Metric Information (bibliography), NBS LC 1070

(includes chart "All You Need to Know About Metric") Not sold separately

The following are other metric materials published by the National Bureau ol Standards. FACTORS FOR HIGH-PRECISION CONVERSION—U.S. CUSTOMARY See AND METRIC UNITS. NBS LC 1071, 8 pages (July 1976). page 5 METRIC STYLE GUIDE (for the News Media). NBS LC 1069, 6 pages See

(September 1976). page 5 UNITS AND SYSTEMS OF WEIGHTS AND MEASURES. NBS LC 1035, See

26 pages (1976). page 5 HOUSEHOLD WEIGHTS AND MEASURES. NBS SP 430, 2 pages (1975), $ .25 SD Stock No. SN 003-003-01542-3. THE INTERNATIONAL SYSTEM OF UNITS (SI). NBS SP 330, 43 pages $ .80 (1974), SD Stock No. SN 003-003-01326-9. WALL CHART OF THE MODERNIZED METRIC SYSTEM. NBS SP 304, 1 $ .65 page (1972), SD Stock No. SN 003-003-00079-5. SUCCESSFUL EXPERIENCES IN TEACHING METRIC. NBS SP 441, $2.30

1 1 5 pages (1 976), SD Stock No. SN 003-003-01 568-7. INTERNATIONAL BUREAU OF WEIGHTS AND MEASURES. NBS SP $3.00

420, 256 pages (1975), SD Stock No. SN 003-003-01408-7.

2 3

ADDITIONAL SOURCES OF METRIC INFORMATION

See Page 5 tor Ordering Information

American National Metric Council, 1625 Massachusetts Ave., NW., Washington, D.C.

20036. Established originally under the auspices of the American National Standards

Institute to provide guidance to industrial and commercial segments of society.

American National Standards Institute (ANSI), 1430 Broadway. New York, N.Y. 10018. Publishes national standards and metric practice guides.

American Society for Testing and Materials. 1916 Race St.. Philadelphia, PA 19103. Publishes assorted metric aids.

The Department of Defense has reproduced for free distribution two NBS metric items —the Modernized Metric System (wall chart in color) and the Metric Conversion Card (wallet card)—which are available upon request Irom your nearest Army school

representative or Army reserve center.

National Council of Teachers of Mathematics, 1906 Association Drive, Reston, VA

22091. Publishes listings of organizations marketing metric material for educators.

National Science Teachers Association. 1201 Sixteenth St., NW., Washington, D.C. 20036. Publishes metric kit for teachers.

Science Service. 1719 N St., NW., Washington, D.C. 20009. Publishes "Things-of- Science" metric kit for students.

U S. Metric Association, Sugarloaf Star Route, Boulder, CO 80302. Distributes educational material and publishes a quarterly newsletter, which is available to members.

National metric conversion boards in other countries can supply general Inlormation about conversion in their respective countries and can also provide referrals to other organizations therein. Their addresses are listed below.

Metric Conversion Board Metrication Board

18-24 Chandos Street 22 Klngsway

St. Leonards, N.S.W. 2065 Australia London WG2B 6LE England

Metric Advisory Board Metrication Board ol Zambia

P. O. Box 10-243 P. O. Box 1968 The Terrace Lusaka. Zambia

Wellington, New Zealand

Metric Commission

South African Bureau of Standards 320 Queen Street

Private Bag Xt9t Oltawa K1A OH5 Canada

Pretoria, South Africa

4

GOOD NEWS

^rou use weights and measures every day of your life.

* Without them, shopping, trade, recreation, and

education would be in a state of hopeless confusion.

You learned the language of measurement so early that

you have probably forgotten the day you first understood

the meaning of "inch, foot, yard, and mile;" of "ounce,

pound, and ton;" of "pint, quart, and gallon;" and that

"100 °F" is uncomfortably hot, while "30 °F" is

uncomfortably cold. These are familiar units of the

"customary" system of measurement.

After many years of debate, our nation recently embarked

on a voluntary coordinated change from the customary

system of measurement (the yard and pound) to the

metric system of measurement (the meter and kilogram).

On December 23, 1975, President Ford signed into law

the Metric Conversion Act of 1975, which established for

the first time a national policy to coordinate America's

changeover to metric. Thus, the United States joined the

worldwide trend toward a comparatively new system called

the "modernized metric system" of measurement.

The names of the units in the metric system may sound

strange to the American ear at first, but fortunately there

are only a few words that have to be learned for everyday

use. These are: the kilometer, meter, centimeter and

millimeter for expressing length and distance; the liter and

milliliter for capacity or volume; the kilogram, gram and

metric ton for weight (mass); the degree Celsius for

temperature; the kilopascal for pressure; and the hectare

for area.

As we convert to the metric system, several units of

measure that we currently use will not change. Time will

continue to be measured in hours, minutes, and seconds;

electric power will still be measured in watts; and our

monetary system will remain the same.

The metric system is already being used in this country

to a greater extent than most people realize. In

international athletic competition, such as swimming and

track and field events, length measurements are given in

meters rather than in yards and feet. Our astronauts, from
the surface of the moon, excitedly told a worldwide

audience how far their rocket had landed from a lunar

hill in meters. You see weights expressed in grams on more

and more packaged items at the grocery store. And the

trend is toward even greater use.

is the metric systembe

INCREASINGIY USED?

he metric system is increasingly in use throughout the

world for two reasons: it is a simple system, and it is

a decimal system.

It is simple because each quantity, such as length (meter)

or weight (gram), has its own unit of measurement, and

no unit is used to express more than one quantity. In the

customary system, however, pound can mean either

force (as in pounds required to break a rope) or weight

(as in a pound of sugar); and ounce can mean either

volume (as the number of ounces in a quart) or weight (as

the number of ounces in a pound).

The metric system is easier than the customary system to

learn to use in solving problems that involve computation.

This is because multiples of metric units are related to each

other by the factor 10. You have probably noticed that

the names of metric units sometimes include prefixes

such as milli, centi, and kilo as in milliliter, centimeter, and

kilogram. These prefixes indicate multiples or submultiples

of the units.

Consider the measurement of length—in the metric

system any measure of length is expressed in meters or

multiples of the meter. A cent/meter is one hundredth of a

meter; a millimeter is one thousandth of a meter; and a k;7ometer is one thousand meters. In the customary

system, an inch is one thirty-sixth of a yard; a foot is one

third of a yard; and a mile is 1760 yards.

The most commonly-used prefixes, and the multiplication

factors they indicate, are given on the following pages.
WEIGHT

1 kilo

1 hecto

1 deka

1

Ideci

1 centi

1 milli

LENGTH

1000 grams

100 grams

10 grams

Igram

0.1 gram

0.01 gram

0.001 gram

1000 meters

100 meters

10 meters

1 meter

0.1 meter

0.01 meter

0.001 meter

units not commonly used
VOLUME

1 hecto

1 ripta I Uuilfl

1

Ideci

1 centi

1 milli —

100 liters

10 liters

lliter

0.1 liter

0.01 liter

0.001 liter

units not commonly used

TEMPERATURE

Prefixes are not commonly used with temperature measurements as they are with those for weight, length, and volume. Temperatures in degrees Celsius, as in the familiar

Fahrenheit system, can only be learned through experience. The following may help to orient you with regard to

temperatures you normally encounter.

0 °C Freezing Point of Water (32 °F)

10 °C A warm winter day (50 °F)

20 °C A mild spring day (68 °F)

30 °C Quite warm—almost hot (86 °F)

37 °C Normal body temperature (98.6 °F)

40 °C Heatwave conditions (104° F)

100 °C Boiling point of water (212 °F)
A visual comparison

of metric and customary units of

measurement

In the examples below, a visual comparison is made of the major

units of the customary and metric systems, by using everyday quantities and sizes for purposes of illustration.

Small

linear dimensions

For expressing small linear

dimensions, such as wrench

sizes, millimeters will replace

inches. For example, a 6-mm

wrench will be a more

commonly-used size than a

1A-inch wrench

Larger

linear dimensions

In expressing larger sizes, the

meter will replace both the

foot and the yard. In the

example shown, a 3 X 4

meter carpet will generally be

sold rather than a 9 X 12 foot

(or 3 X 4 yard) carpet.

Great

Distances

The kilometer will replace the

mile in expressing great

distances, such as distances

between cities. The example

shows the replacement for a sign 25 miles from Centerville:

it would read 40 kilometers.
Small

Weights

When we purchase small

quantities of things, such as candy, we will use grams

instead of ounces. For example,

250 grams will replace 9 ounces.

Larger

Weights

The purchase of large items,

such as meat, will be figured

in kilograms rather than

pounds. In the example

shown, a 2-kilogram roast will

replace a 4.5-pound roast.

Volume

When you order a tankful of

gas, you may note that it will

take 60 liters rather than 16

gallons.

Speed

Our automobile speedometers

will change from miles per

hour to kilometers per hour

as the speed limit signs on our highways are likewise changed.

On the speedometers shown,

an 80 kilometers per hour

speed replaces 50 miles

per hour.
a handy guide for estimating the most common household measurements

WEIGHT

kilogram =2.2 pounds

m

500 grams

= 1.1 pound

30 grams

1.1 ounces

nti

ims = 8.8 ounces

100 grams = 3.5 ounces

1 LENGTH

10 11 12 13

inches

I I I I I I I I I I I

2

1 1 1 1 1 1 1 1 1 1 1 1 1 1

1

3 4

i 1 1 I i I i I i I i I i I i i I I I i I i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1, l lll; i I i

30 centimeters = 1 foot
1 liter =1.06 quarts
Calculations

using metric and customary units

The statement and solution of three everyday problems are given in both customary

and metric units, providing a side by side comparison of the systems.

Problem: What is the area of the floor of a room with the

following dimensions?

Metric Units

475 centimeters

380 centimeters

Customary Units

Length 15 ft 7 in

Width 12 ft 6 in

SOLUTION. The area is determined by multiplying the

length of the room by its width. Note that for room dimensions given in mixed customary units it is necessary to first

reduce them to a common unit expression which, in this

case, may be either feet or inches.

Alternate Solution

Room Dimensions in Feet

tength

15 — feet 12

Width

12V2 feet

15 — X 12V2 square feet 12

187 25

X — =

12 2 4675

24

square feet

19 = 194 — square feet 24 = 22 square yards (approx.)

CUSTOMARY—

Room Dimensions in

Inches

Multiply feet by 12 to convert

to inches

Length (15 X 12) + 7 = 187 in

Width (12 X 12) + 6 = 150 in

187 X 150 = 28 050 square inches

Total square inches divided by

number of square inches in a square foot (144) equals

number of square feet

28 050 + 144 = 195

square feet (approx.)

Total square feet divided by

number of square feet in a square yard (9) equals num

of square yards

iber

195 + 9 = 22 square

yards (approx.)

METRIC—

Room Dimensions in

Centimeters

Length 475 cm

Width 380 cm

475 X 380

180 500 square cm

Total square centimeters

divided by number of square

centimeters in a square meter

(10 000) equals number of

square meters; i.e. move

decimal point 4 places to left

' V

'

180 500 + 10 000 =

18 square meters

(approx.)
Alternate Solutions

lb oz kg

Meat 4 9 2.07 Potatoes 3 4 1.47

Tomatoes 2 15 1.33 Cereal 1 7 0.65 10 35 5.52 Or 12 3 Or 12 1b or 5.5 kg

(approx.) (approx.)

c

Alternate Solutions

gal qt pt liters Milk 1 2 1 6.5 Water 3 1 3.5 Flavoring 1/2 0.25

Totals T T ~2~y7 10.25

2 2 y2 or 2V2 gal or 10 liters (approx.) (approx.)

What is the approximate total weight of the contents of a basket that

contains the following items:

Weight

Customary Units Metric Units

Meat 4lb9oz 2.07 kilograms

Potatoes 3lb4oz 1.47 kilograms

Tomatoes 2lbl5oz 1.33 kilograms

Cereal 1 lb 7 oz 650 grams

Solution of Problem

Customary

Weight in Ounces

Weight in pounds multiplied

by 16 gives weight in ounces

Meat (4 X 16) + 9 = 73 2070

Potatoes (3 X 16) + 4 = 52 1470

Tomatoes (2 X 16) + 15 = 47 1330

Cereal (1 X 16) + 7 = 23 650

195 5520

Metric

Weight in Grams

multiply

kilograms

by 1000 to

convert

to grams

195 divided by 16 = 12 lb (approx.) or 5.5 kilograms (approx.)

Volume

What is the volume of the following two comparable but not equal

mixtures:

Customary Metric

Units Units

Milk 1 gal 2 qt 1 pt 6.5 liters Water 3 qt 1 pt 3.5 liters Flavoring V2 pt 250 milliliters

Solution of Problem

Customary

Volume in Pints

Multiply gallons by 8, and

quarts by 2 to convert to

pints

Milk

(1 X 8) + (2 X 2) + 1 = 13

Water

(3 X 2) + 1 Flavoring 1/2

Metric

Volume in Milliliters

6500

3 500

250

10250

multiply liters by 1000 to

convert to

milliliters

20 1/2

201/2 2 = 10 qt (approx.) or 10 liters (approx.)

10 + 4 = 2V2 gal (approx.) or 10 liters (approx.)
Everyday units of

MEASUREMENT

The few metric units of measurement that we will be using in our everyday lives and their

approximate sizes are given on this page.

Measurement

Metric

Unit

Approximate

Size of Unit

Length millimeter

centimeter

meter

ki lomeier

diameter of a paper clip wire

a little more than the width

of a paper clip (about 0.4 inch)

a little longer than a yard

(about 1.1 yards)

somewhat further than Vi mile

(about 0.6 mile)

Weight (mass) gram

kilogram

metric ton

a little more than the weight

of a paper clip

a little more than 2 pounds

(about 1.1 pounds)

a little more than a short

ton (about 2200 pounds)

Volume

— —

milliliter

liter

five of them make a teaspoon

a little larger than a quart

(about 1.06 quarts)

Area hectare about 2.5 acres

Pressure kilopascal atmospheric pressure is about

100 kilopascals

Temperature degree Celsius see temperature scale below

TEMPERATURE

°C -40 -20 0 20 37 60 80 100

°F

1 r-

-40 0

h i—H '—i

1 h

32 80 98.6 160 212

t t t

water body water

freezes temperature boils
What Will

METRIC MeanTo You?

the MARKETPLACE

yV s metric measures become commonplace, one of the

# m first things you will notice as you shop will be the new

metric expressions for weight, volume, and length on

packaged goods.

Currently, in packaged foods, the number of different

expressions of measurement you encounter in one day's

shopping is bewildering. Weights are expressed in

avoirdupois ounces and pounds; fluid measures are

expressed in gallons, liquid quarts, pints, and fluid ounces;

and dry measures are expressed in bushels, pecks, dry

quarts, and pints. Only our long familiarity with the

customary system has made it usable.

With metric labeling, weight will be expressed only in

grams or kilograms; volume will be expressed only in

liters or milli/Zters; and length will be expressed only in

meters, centimeters or millimeters. Clearly, metric is much

less confusing and will be much easier to use when

shopping.

the HOME

Some of the most frequent measurements made in the

home are those for cooking and baking. The practice

that will be most generally followed in metric recipes

should not differ from our current practice. Metric "cup and

spoon" measures are only slightly larger than, and can
be used interchangeably with, the customary "cup and

spoon" measures in common use in American households.

It is only those few ingredients that are now measured

by weight (pounds and ounces) that will be expressed

differently in metric recipes. To convert a customary recipe

to metric just remember that a pound is about 450 grams

and an ounce is about 28 grams.

Temperatures in metric recipes are given in degrees

Celsius rather than degrees Fahrenheit. If your range

thermometer or thermostat is calibrated in degrees

Fahrenheit, simply multiply the Celsius temperature given

in your recipe by 2 to obtain, quite closely, the corresponding Fahrenheit temperature. This method of conversion is

accurate within 9 °F over the range 240-400 °F.

as aWORKER

Many mechanics, machinists, and assembly plant

workers will use metric tools, such as wrenches, dies,

and taps, that are different in size from those now used.

For a while, because of the need to maintain tools in

metric and customary unit sizes, they will have a larger

number of such tools from which to select. In the long run,

however, use of metric units and tools should reduce

the number of tools required as the number of sizes of

fasteners and other components used in the manufacture

of products is reduced.

Sales personnel in hardware, paint, and fabric stores will

also be affected by the metric changeover. When a

customer wishes to purchase lumber or paint or wallpaper,

the hardware store employee may be required to

calculate for the customer the amount needed to cover

an area with paint or wallpaper, or how much lumber

will be needed to build a deck. With the use of metric,

these calculations will be less complicated. The fabric store

employee may likewise be asked to calculate the amount

of cloth needed to drape a window, cover a chair, or

make a dress.

For most other workers, the knowledge of metric units

that they will learn as consumers will enable them to

carry out their duties as efficiently as in the past.
A Word from the Acting Director

hope you have found this booklet helpful in

understanding the metric system of measurement,

particularly as it pertains to your everyday life. With

passage of the Metric Conversion Act of 1975, we have

entered a new, accelerated phase on the road to

metric—a phase that makes this booklet, newly revised,

even more useful.

It is now national policy to coordinate and plan for

increasing use of the metric system. More and more we will

see the results of this policy as our children are taught

the metric system in school; as road signs on our highways

begin to give distances in kilometers and speed limits

in kilometers per hour; as more consumer goods are made

and labeled to metric specifications; and as the news

media disseminate information in metric units.

The National Bureau of Standards has been proud to

serve as the Nation's principal metric resource during the

period of national policy debate. Although many of the

Bureau's metric information functions will be assumed by

the new U.S. Metric Board, NBS will continue to serve

as the authoritative source of accurate, compatible, and

useful physical measurements. We will also continue to

work with State and Federal agencies, universities,

industry, and other groups as the focal point for assuring

the integrity of measurements used throughout the

United States.

ERNEST AMBLER

For further information contact:

NATIONAL BUREAU OF STANDARDS

WASHINGTON, D.C. 20234
U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Washington, D.C. 20234

OFFICIAL BUSINESS

POSTAGE AND FEES PAID

U.S. DEPARTMENT OF COMMERCE

COM-215

Fourth Class

A Consumer's

GUIDE

FROM THE NATIONAL

BUREAU OF STANDARDS

U.S. DEPARTMENT

OF COMMERCE

by

Louis E. Barbrow

Coordinator of Metric Activities

Institute for Applied Technology

National Bureau of Standards

Washington, D.C. 20234

NBS CONSUMER INFORMATION SERIES 7

Editor: Suellen Halpin

Center for Consumer Product Technology

Institute for Applied Technology

National Bureau of Standards

Issued: October 1973

Revised: October 1976

U.S. DEPARTMENT OF COMMERCE

Elliot L. Richardson, Secretary

Edward O. Vetter, Under Secretary

Dr. Betsy Ancker-Johnson,

Assistant Secretary for Science

and Technology

NATIONAL BUREAU OF STANDARDS

Ernest Ambler, Acting Director

For sale by the Superintendent of

Documents, U.S. Government Printing Office

Washington, D.C. 20402

Price 35 cents

* GPO : 1974 O - 560-335
UNITED STATES DEPARTMENT OF COMMERCE

Elliot L. Richardson, Secretary

NATIONAL BUREAU OF STANDARDS / Ernest Ambler. Acting Director

Special Publication 304A. Revised August 1976

Brief History of

MEASUREMENT SYSTEMS

with a Chart of the Modernized Metric System

"Weights and measures may be ranked among the necessaries of

life to every individual of human society. They enter into the eco- nomical arrangements and daily concerns of every family. They are necessary to every occupation of human industry; to the distribution and security of every species of property; to every transaction

of trade and commerce; to the labors of the husbandman; to the ingenuity of the artificer; to the studies of the philosopher; to the

researches of the antiquarian, to the navigation of the mariner, and

the marches of the soldier; to all the exchanges of peace, and all the

operations of war. The knowledge of them, as in established use, is among the first elements of education, and is often learned by those

who learn nothing else, not even to read and write. This knowledge

is riveted in the memory by the habitual application of it to the employments of men throughout life." JOHN QUINCY ADAMS

Report to the Congress, 1821

Weights and measures were among

the earliest tools invented by man.

Primitive societies needed rudimentary measures for many tasks: constructing

dwellings of an appropriate size and

shape, fashioning clothing, or bartering

food or raw materials.

Man understandably turned first to

parts of his body and his natural sur- roundings for measuring instruments.

Early Babylonian and Egyptian records

and the Bible indicate that length was

first measured with the forearm, hand,

or finger and that time was measured by

the periods of the sun, moon , and other

heavenly bodies. When it was necessary

to compare the capacities of containers

such as gourds or clay or metal vessels,

they were filled with plant seeds which

were then counted to measure the vol- umes. When means for weighing were

invented, seeds and stones served as standards. For instance, the "carat," still used as a unit for gems, was derived

from the carob seed.

As societies evolved, weights and

measures became more complex. The

invention of numbering systems and the

science of mathematics made it possible

to create whole systems of weights and

measures suited to trade and commerce,

land division, taxation, or scientific re- search. For these more sophisticated uses it was necessary not only to weigh

and measure more complex things—it was also necessary to do it accurately

time after time and in different places.

However, with limited international ex- change of goods and communication of

ideas, it is not surprising that different

systems for the same purpose developed

and became established in different parts

of the world—even in different parts of

a single continent.

The English System

The measurement system commonly

used in the United States today is nearly

the same as that brought by the colonists from England. These measures had

their origins in a variety of cultures

Babylonian, Egyptian, Roman, AngloSaxon, and Norman French. The ancient "digit," "palm," "span," and

"cubit" units evolved into the "inch,"

"foot," and "yard" through a complicated transformation not yet fully understood.

Roman contributions include the use

of the number 12 as a base (our foot is divided into 12 inches) and words from

which we derive many of our present

weights and measures names. For example, the 12 divisions of the Roman

"pes," or foot, were called unciae. Our

words "inch" and "ounce" are both derived from that Latin word.

The "yard" as a measure of length can be traced back to the early Saxon

kings. They wore a sash or girdle

around the waist—that could be re- moved and used as a convenient measuring device. Thus the word "yard" comes

from the Saxon word "gird" meaning

the circumference of a person's waist.

Standardization of the various units

and their combinations into a loosely

related system of weights and measures sometimes occurred in fascinating ways.

Tradition holds that King Henry I decreed that the yard should be the dis- tance from the tip of his nose to the

end of his thumb. The length of a fur- long (or furrow-long) was established

by early Tudor rulers as 220 yards. This

led Queen Elizabeth I to declare, in the

16th century, that henceforth the traditional Roman mile of 5 000 feet would

be replaced by one of 5 280 feet, making the mile exactly 8 furlongs and providing a convenient relationship between

two previously ill-related measures. Thus, through royal edicts, England

by the 18th century had achieved a

greater degree of standardization than

the continental countries. The English

units were well suited to commerce and

trade because they had been developed

and refined to meet commercial needs.

Through colonization and dominance of

world commerce during the 17th, 18th,
THE MODERNIZED

metric

system The International System of Units-Si

is a modernized version of the metric system established by international

agreement. It provides a logical and interconnected framework for all measurements in science, industry, and commerce. Officially abbreviated

SI, the system is built upon a foundation of seven base units, plus two

supplementary units, which appear on this chart along with their definitions. All other SI units are derived from these units. Multiples and submultiples are expressed in a decimal system. Use of metric weights and

measures was legalized in the United States in 1866, and since 1893 the

yard and pound have been defined in terms of the meter and the kilogram.

The base units for time, electric current, amount of substance, and lumi- nous intensity are the same in both the customary and metric systems.

COMMON CONVERSIONS

Accurate to Six Significant Figures MULTIPLES AND PREFIXES

These Prelixes May Be Applied To All SI Units

Symbol

ftyd

yd'

yd'

qt

lb °F

L

g

kg °C

When You Know

Number Of inches

feet yards

miles square yards

acres cubic yards

quarts {lq} ounces (avdp) pounds (avdp) degrees

Fahrenheit

millimeters meters

meters

kilometers square meters

°hectares

cubic meters

"liters grams

kilograms degrees

Celsius

Multiply by

'25.4 "0 3048

A 0.9144

1.609 34

0.836 127

0.404 686

0.764 555

0.946 353

28 349 5 0.453 592

*5/9 (after subtracting 32)

0.039 370 1 3.280 84

1 093 61

0.621 371

1.195 99

2.471 05

1.307 95

1.056 69

0.035 274 0

2.204 62

"9/5 (then add 32)

To Find Number Of

B millimeters meters

meters

kilometers square meters

c hectares cubic meters

"liters grams

kilograms

degrees

Celsius

inches

feet yards

miles square yards

acres

cubic yards

quarts (lq) ounces (avdp) pounds (avdp) degrees

Fahrenheit

Symbol mm

L

g

kg °c

ftyd

yd'

yd'

qt

lb °F

B tor example, 1 in = 25.4 mm, so 3 inches would be

(3 in) (25.4 = 76.2 mm

"hectare is a common name for 10 000 square meters

°liter is a common name for fluid volume of 0 001 cubic meterNote: Most symbols are written with lower case letters; exceptions

are units named after persons for which the symbols are capitalized. Periods are not used with any symbols

Multiples and Submultiples

1 000 000 000 000 000 000

1 000 000 000 000 000

1 000 000 000 000

1 000 000 000

1 000 000

1 000

100

10 Base Unit 1

0.1

0.01

0.001

0.000 001

0.000 000 001

0.000 000 000 001

0.000 000 000 000 001

0.000 000 000 000 000 001

^ apply to gram in case of mass

Prefixes Symbols

10 ,B exa (ex' a)

10 s peta (pet a) 10" tera (ter'a)

10 s giga (ji'ga)

10 c mega (meg a)

10 3 kilo (kTl'o)

hecto (hek to)

deka (dek' a)

10

10

10

10

10

10

10

10

"9 nano (nan 6)

10 " 1? pico (pe'ko) c

10 ,s femto (fern' to) f

10 "atto (at' to) a

deci (des i)

centi (sen' tT)

milli (mif"i) m

n

National Bureau of Standards

Special Publication 304A (Revised August 1976) For sale by the Superintendent ol Documents, U.S. Governmant Printing Office. Washington, D C 20402

Price 3S cents-Stock No 003-003-01713-2 REFERENCES

NBS Special Publication 330, Latest Edition, International System

of Units (SI), available by purchase from the Superintendent of Documents, Government Printing Office, Washington. DC.

20402; Price 80 cents-Stock No 003 - 003 - 01326-9

American National Standard for Metric Practice. 22101. available by purchase from the American National Standards Institute. 1430 Broadway. NY. N Y 10018

SI Units and Recommendations tor the Use of Their Multiples and

of Certain Other Units, available by purchase from the American

National Standards Institute. 1430 Broadway. N Y . N Y 10018; order as ISO Standard 1000
SEVEN BASE UNITS

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

V«u of 4

1 650 763.73 wavelengths

-red line of the spectrum

7U71 WAVELENGTHS

WAVELENGTH

[ AAAAAA/

by means or light wave*

The SI unit of area is the square meter (m').

The SI unit of volume is the cubic meter (m3

). The

liter (0.001 cubic meter), although not an SI unit, is commonly used to measure fluid volume.

d for the unit of mass, the kilogram, is a

jlatinum-iridium alloy kept by the Internau of Weights and Measures at Paris. A du3 custody of the National Bureau of Standas the mass standard for the United States,

nly base unit still defined by an artifact.

commonly used term lor "mess."

7 U.S. PROTOTYPE KILOGRAM ^ p

NO 20

The SI unit of force is the newton (N). One newton is the force which, when

applied to a 1-kilogram mass, will give

the kilogram mass an acceleration of

1 (meter per second) per second.

1 N = 1 kgm/s2

ACCELERATION

-»-of Im/s"

The SI unit for pressure is the pascal (Pa).

1 Pa = 1 N/m2 The SI unit for work and energy of any

kind is the joule (J).

1 J = 1 N-m

The SI unit for power of any kind is the watt(W).

1 W = 1 J/s

the duration of 9 1 92 631 770

associated with a specified

-133 atom. It is realized by

he resonance frequency of

iy pass through a system of cavity into a detector.

seam spectrometer of -clock." Only those atom* vrhoee

- m Vw transition region men Via deHctor. When

TRANSITION REGION (CAVITY) OSCILLATING FIELD CESIUM DETECTOR

DEFLECTION MAGNET DEFLECTION MAGNET

The number of periods or cycles per second

is called frequency. The SI unit for frequency

is the hertz (Hz). One hertz equals one cycle

per second. The SI unit for speed is the meter per second

(m/s). The SI unit for acceleration is the (meter per second) per second (m/s2

).

Standard frequencies and correct time are broadcast from WVW, WWVB, and WWVH,

and stations of the U.S. Navy. Many short- wave receivers pick up WVW and WWVH, on

frequencies of 2.5, 5, 10, 15, and 20 megahertz.

ipere is defined as that current which, if maintained in each of two

irallel wires separated by one meter in free space, would produce

between the two wires (due to their magnetic fields) of 2 x 10-7

for each meter of length.

tIm

i

FORCE

I =Jx10"'N M—e-lrn—». -e iA

The SI unit of voltage is the volt (V). 1V= 1 W/A

The SI unit of electric resistance is the ohm (O).

1 a = 1 v/a

TEMPERATURE

he frac- jrmodyle triple >erature

3ro". -40

FAHRENHEIT °f|

>C

Hat,, MEASUREMENT

Bona SYSTEMS

3TBody Temperature

0 Water Freezes- -

Absolute 0 Zero

On the commonly used Celsius temperature scale, water freezes at about 0 °C and boils at about 100 °C. The °C is defined as an interval of 1 K, and the Celsius temperature 0 °C is defined as 273.15 K.

1.8 Fahrenheit degrees are equal to 1.0°C or 1.0 K; the Fahrenheit scale uses 32 °F as a temperature cor- responding to 0 °C.

THERMOMETER

(ELECTRICAL RESISTANCE

TYPE)

WATER VAPOR

REFRIGERATING BATH

The standard temperature at the triple point of water is provided by a special

cell, an evacuated glass cylinder containing pure water. When the cell is cooled

until a mantle of ice forms around the re- entrant well, the temperature at the inter- face of solid, liquid, and vapor is 273.16 K. Thermometers to be calibrated are placed

in the reentrant well.

The mole is the amount of substance of a system that contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12.

When the mole is used, the elementary

entities must be specified and may be

atoms, molecules, ions, electrons, other

particles, or specified groups of such

particles.

The SI unit of concentration (of amount of substance) Is the mole per cubic meter (mol/m3

).

The candela is defined as the luminous

intensity of 1/600 000 of a square meter

of a blackbody at the temperature of

freezing platinum (2045 K).

The SI unit of light flux is the lumen

(Im). A source having an intensity of 1 candela in all directions radiates a light flux of 4 1T lumens. A 100-wtm ligW bulb

emits about 1700 lumens

TWO SUPPLEMENTARY UNITS

angle with its

i circle that is

al in length to SOLID ANGLE

The steradian is the solid angle with

its vertex at the center of a sphere

that is subtended by an area of the spherical surface equal to that of a square with sides equal in length to the radius.

..'iJI'.'ll/. 'lU'V'i'^'ili'^l'V'-b

50 60 70 80 90

Government Printing Office, Washington, D.C. 20402, for 65 cents-Stock No. 003-003-01072-3
and 19th centuries, the English system

of weights and measures was spread to and established in many parts of the

world, including the American colonies.

However, standards still differed to an

extent undesirable for commerce among

the 13 colonies. The need for greater

uniformity led to clauses in the Articles

of Confederation (ratified by the original colonies in 1781) and the Constitution of the United States (ratified in 1790) giving power to the Congress to

fix uniform standards for weights and

measures. Today, standards supplied to

all the States by the National Bureau of

Standards assure uniformity throughout

the country.

The Metric System

The need for a single worldwide coor- dinated measurement system was recognized over 300 years ago. Gabriel Mouton, Vicar of St. Paul in Lyons, proposed

in 1670 a comprehensive decimal meas- urement system based on the length of one minute of arc of a great circle of

the earth. In 1671 Jean Picard, a French

astronomer, proposed the length of a pendulum beating seconds as the unit

of length. (Such a pendulum would

have been fairly easily reproducible,

thus facilitating the widespread distribution of uniform standards.) Other proposals were made, but over a century

elapsed before any action was taken. In 1790, in the midst of the French

Revolution, the National Assembly of

France requested the French Academy

of Sciences to "deduce an invariable

standard for all the measures and all the

weights." The Commission appointed by

the Academy created a system that was,

at once, simple and scientific. The unit

of length was to be a portion of the

earth's circumference. Measures for capacity (volume) and mass (weight) were to be derived from the unit of

length, thus relating the basic units of

the system to each other and to nature. Furthermore, the larger and smaller

versions of each unit were to be created

by multiplying or dividing the basic

units by 10 and its t powers. . This fea- ture provided a great convenience to

users of the system, by eliminating the

need for such calculations as dividing

by 16 (to convert ounces to pounds) or by 12 (to convert inches to feet). Similar calculations in the metric system

could be performed simply by shifting

the decimal point. Thus the metric sys- tem is a "base- 10" or "decimal" system.

The Commission assigned the name

metre — which we spell meter — to the unit of length. This name was derived from the Greek word metron,

meaning "a measure." The physical

standard representing the meter was to be constructed so that it would equal one ten-millionth of the distance from

the north pole to the equator along the

meridian of the earth running near Dunkirk in France and Barcelona in Spain.

The metric unit of mass, called the

"gram," was defined as the mass of one

cubic centimeter (a. cube that is 1/100

of a meter on each side) of water at its temperature of maximum density. The

cubic decimeter .(a cube 1/ 10 of a meter on each side) was chosen as the unit of

fluid capacity. This measure was given

the name "liter." Although the metric system was not

accepted with enthusiasm at first, adoption by other nations occurred steadily

after France made its use compulsory

in 1840. The standardized character and

decimal features of the metric system

made it well suited to scientific and en- gineering work. Consequently, it is not

surprising that the rapid spread of the

system coincided with an age of

rapid technological development. In the

United States, by Act of Congress in

1866, it was made "lawful throughout

the United States of America to employ

the weights and measures of the metric

system in all contracts, dealings or court

proceedings."

By the late 1860's, even better metric

standards were needed to keep pace

with scientific advances. In 1875, an in- ternational treaty, the "Treaty of the

Meter," set up well-defined metric standards for length and mass, and established permanent machinery to recom- mend and adopt further refinements in

the metric system. This treaty, known

as the Metric Convention, was signed by

17 countries, including the United

States. As a result of the Treaty, metric

standards were constructed and distributed to each nation that ratified the

Convention. Since 1893, the internationally agreed-to metric standards have

served as the fundamental weights and

measures standards of the United States. By 1900 a total of 35 nations—in- cluding the major nations of continental

Europe and most of South America

had officially accepted the metric sys- tem. Today, with the exception of the

United States and a few small countries,

the entire world is using predominantly

the metric system or is committed to such use. In 1971 the Secretary of Commerce, in transmitting to Congress the

results of a 3-year study authorized by

the Metric Study Act of 1968, recom- mended that the U.S. change to predominant use of the metric system

through a coordinated national program. The Congress is now considering

this recommendation.

The International Bureau of Weights

and Measures located at Sevres, France,

serves as a permanent secretariat for the

Meter Convention, coordinating the ex- change of information about the use and refinement of the metric system. As

measurement science develops more precise and easily reproducible ways of defining the measurement units, the General Conference on Weights and Measures—the diplomatic organization made

up of adherents to the Convention

meets periodically to ratify improvements in the system and the standards.

In 1960, the General Conference

adopted an extensive revision and simplification of the system. The name Le

Systeme International d' Unites (International System of Units), with the in- ternational abbreviation SI, was adopted

for this modernized metric system. Further improvements in and additions to SI were made by the General Confer- ence in 1964, 1968, 1971, and 1975.

i} U.S. GOVERNMENT PRINTING OFFICE : 1976 0 - 225-562

I