ward a Met

¢ The Metric Program seeks to accelerate the national transition to the metric
system of measurement, the preferred system of weights and measures for
United States trade and commerce.

¢ Implementing the 1988 amendments to the Metric Conversion Act of 1975,
the Metric Program coordinates the metric transition activities of all Federal
agencies.

¢ The Program provides leadership and assistance on metric use and
conversion to businesses, state and local governments, standards
organizations, trade associations, and the educational community.

¢ Under the banner “Toward a Metric America,” the Metric Program has
sought to build state and regional partnerships to: (1) accelerate adoption of
the metric system in trade and commerce; (2) encourage use of the metric
system in all facets of education, including honing of worker skills; and (3)
develop positive and enjoyable programs of public awareness.

¢ Current Metric Program initiatives focus on education and public awareness
to gain broad-based support for national metrication from industry and the
general public.

¢ The news media have an important role in assisting the American public
through this period of metric transition. Increasingly, workers are being
trained in the metric units required to perform their jobs. Americans will
compete more successfully in the global marketplace when they understand
and “speak” the international language of measurement. The Nation’s metric
transition will benefit from the media’s correct and positive use of metric
language and symbols. The units, symbols, and other notations used in this
guide are in accord with the International System of Units, which is interpreted
or modified for use in the United States by the Secretary of Commerce

(55 FR 52242, December 20, 1990).

NIST Contact:

Director, Metric Program
National Institute of Standards and
Technology
Gaithersburg, MD 20899
(301) 975-3690 FAX: (301) 948-1416
is email: metric_prg@nist.gov
‘October 1997 URL Address: http://www.nist.gov/metric


Table 1: COMMON PREFIXES FOR METRIC UNITS

Factor Prefix Symbol
1 000 000 10° mega M
1.000 10 kilo k
0.01 lO” centi c
0,001 10% milli m
0.000 001 10° micro L
Table 2: METRIC CONVERSION FACTORS (Approximate)
Symbol When you know Multiply by To find Symbol
Number of Number of
LENGTH
in inches 2) centimeters cm
ft feet 0.3 meters m
yd yards. 0.9 meters m
mi miles 1.6 kilometers km
AREA
in? square inches 6.5 square centimeters cm2
ft? square feet 0.09 square meters m2
yd? square yards 0.8 square meters m2
mi? square miles 2.6 square kilometers km2
acres 0.4 hectares ha
WEIGHT
oz ounces 28 grams g
Ib pounds 0.45 kilograms kg
short tons 0.9 metric tons i
(2000 pounds)
VOLUME
tsp teaspoons '5) milliliters mL
Tbsp tablespoons 15 milliliters mL
in? cubic inches 16 milliliters mL
fl oz fluid ounces 30 milliliters mL
iG cups. 0.24 liters II,
pt pints 0.47 liters L
qt quarts 0.95 liters L
gal gallons 3.8 liters IL
cic cubic feet 0.03 cubic meters m3
yd3 cubic yards 0.76 cubic meters m3
PRESSURE
inHg inches of mercury 3.4 kilopascals kPa
psi pounds per square inch 6.9 kilopascals kPa
TEMPERATURE (exact)
oF degrees Fahrenheit 5/9 (after degrees Celsius te

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METRIC

STYLE GUIDE

FOR THE NEWS MEDIA

U.S. DEPARTMENT OF COMMERCE
Technology Administration
National Institute of Standards and
Technology



METRIC STYLE GUIDE

In most cases, familiarity with the following metric units
will be sufficient for everyday transactions:

Name Symbol Approximate Size
length meter m 39 1/2 inches

kilometer km 0.6 mile

centimeter cm width of a paper clip

millimeter mm thickness of a dime
area hectare ha 2 1/2 acres

square meter m? 1.2 square yards
weight gram g weight of a paper clip
(or mass) kilogram kg 2.2 pounds

metric ton t long ton (2240 pounds)
volume liter L one quart and 2 fluid ounces

milliliter mL 1/5 teaspoon,
pressure kilopascal kPa atmospheric pressure is

about 100 kPa

Units of time and electricity are already metric units.

The Celsius temperature scale should be used; familiar points on this scale are:

°C °F
Temperature at which water freezes te) B82)
Temperature at which water boils 100 212
Normal body temperature 37 98.6
Comfortable room temperature 20-25 68-77
Prefixes Spelling

Some of the metric units listed above include
prefixes such as kilo, centi, and milli. Prefixes,
added to a unit name, create larger or smaller
units by factors that are powers of 10. For
example, add the prefix kilo, which means a
thousand, to the unit gram to indicate

1000 grams; thus 1000 grams become

1 kilogram. The more common prefixes are
shown in Table 1.

All units and prefixes should be spelled as
shown in this guide.

Conversions

Conversions should follow a rule of reason: do
not use more significant digits than justified by
the precision of the original data. For example,
36 inches should be converted to 91centimeters,
not 91.44 centimeters (36 inches x 2.54
centimeters per inch = 91.44 centimeters), and
40.1 inches converts to 101.9 centimeters, not
101.854. Table 2 lists many of the more
commonly used conversion factors.


Capitals

UNITS: The names of all units start with a lower
case letter except, of course, at the beginning of
a sentence. There is one exception: in “degree
Celsius” (symbol °C) the unit “degree” is lower
case, but the modifier “Celsius” is capitalized.
Thus, body temperature is written as 37 degrees
Celsius.

SYMBOLS: Unit symbols are written in lower
case letters except for liter and those units
derived from the name of a person (m for meter,
but W for watt, Pa for pascal, etc.).

PREFIXES: Symbols of prefixes that mean a
million or more are capitalized and those less
than a million are lower case (M for mega
(millions), m for milli (thousandths)).

Plurals

UNITS: Names of units are made plural only
when the numerical value that precedes them
is more than one. For example, 0.5 liter, but
250 milliliters. Zero degrees Celsius is an
exception to this rule.

SYMBOLS: Symbols for units are never
pluralized (250 mm = 250 millimeters).

Incorrect Terms

The prefix “kilo” stands for one thousand of the
named unit. It is not a stand-alone term in the
metric system. The most common misuse of this
is the use of “kilo” for a “kilogram” of
something. The word “micron” is an obsolete
term for the quantity “micrometer.” Also
"degree centigrade” is no longer the correct
unit term for temperature in the metric system;
it has been replaced by degree Celsius.

Pronunciation .
The pronunciation of common metric units is
well known, except for pascal, which rhymes.
with rascal, and hectare, which rhymes with
bare.

The first syllable of every prefix is accented,
not the second syllable. Example: KILL-oh-meter,
not kil-LOM-meter.

Spacing

A space is used between the number and the
symbol to which it refers. For example: 7 m,
31.4 kg, 37 °C.

When a metric value is used as a one-
thought modifier before a noun, hyphenating
the quantity is not necessary. However, if a
hyphen is used, write out the name of the
metric quantity with the hyphen between the
numeral and the quantity. For example:

a 2-liter bottle, NOT a 2-L bottle;

a 100-meter relay, NOT a 100-m relay;

35-millimeter film, NOT 35-mm film.

Spaces are not used between prefixes and
unit names nor between prefix symbols and
unit symbols. Examples: milligram, mg;
kilometer, km

Period
DO NOT use a period with metric unit names
and symbols except at the end of a sentence.

Decimal Point

The dot or period is used as the decimal point
within numbers. In numbers less than one, zero
should be written before the decimal point.
Examples: 7.038 g; 0.038 g.

For More Detail

Approximate conversions for many units are
given in Table 2. Some writers will require
detailed information on units peculiar to their
fields.

Detailed metric information and precise
conversions are available in NIST Special
Publication 811 (SP 811), “Guide for the Use of
the International System of Units (SI)." It is
available by calling the NIST General Inquiries
Office at (301) 975-3058, email:
inquiries@nist.gov.

A "Metric Editorial Guide” is available from
the American National Metric Council, 4340 East
West Highway, Suite 401, Bethesda, MD 20814-
4411; (301) 718-6508. A “Guide to the Use of
the Metric System” is available from the U.S.
Metric Association, 10245 Andasol Avenue,
Northridge, CA 91325-1504; (818) 368-7443.