Recommended Agency Procedures for 

Implementing Federal Metric Policy 

(NISTIR 4855)

May 1992

U.S. DEPARTMENT OF COMMERCE 

Technology Administration 

National Institute of Standards and Technology 

Metric Program 

Technology Services 

Gaithersburg, MD 20899 

James B. McCracken 

Gary P. Carver 

U.S. DEPARTMENT OF COMMERCE 

Barbara Hackman Franklin, Secretary 

TECHNOLOGY ADMINISTRATION 

Robert M. White, Under Secretary of Technology 

NATIONAL INSTITUTE OF STANDARDS 

AND TECHNOLOGY 

John W. Lyons, Director 

Document Content: 

● Purpose and Scope

● Background

● Reference Documents

● Agency Actions

● Practical and Meaningful Measurement Expressions

● Data Requests, Recordkeeping, and Reports 

❍ Reports and Questionnaires

❍ Records

❍ Recordkeeping—ADP Considerations

● Assistance

● References

I. PURPOSE AND SCOPE 

The primary purpose of these recommended procedures is to assist federal agencies in their 

transition to the use of metric units 1 in regulations, data 

requests, recordkeeping, and reports. Although this document is intended for federal use, it 

may also be useful to state and local government agencies 

and other organizations. The primary purpose of these recommended procedures is to assist 

federal agencies in their transition to the use of metric units 1 in regulations, data requests, 

recordkeeping, and reports. Although this document is intended for federal use, it may also 

be useful to state and local government agencies and other organizations.

II. BACKGROUND 

Recommended Agency Procedures for Implementing Federal Metric Policy (NISTIR 4855)

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The policy of the United States, as stated by Congress,2 is to require that each federal 

agency, by a date certain and to the extent economically feasible 

by the end of fiscal year 1992, use the metric system in contracts, grants and other 

business related activities. The federal Interagency Council on 

Metric Policy (ICMP)3 recommends that, in support of the national metric goals and the 

"Metric Conversion Policy for Federal Agencies" [1], federal 

agencies ensure;

❍ That existing measurement-sensitive4 regulations or requirements are amended as 

necessary to accommodate the transition to use of the metric system; 

and that metric units are the preferred units in new or revised regulations or 

requirements. 

❍ That metric measurement expressions used are both meaningful 5 values. 

III. REFERENCE DOCUMENTS 

There are a number of federal metric-related reference documents. These include the 

Executive Order on metric implementation [l], the interpretation of 

the metric system ill, guidance on using the metric system [2], and metrication in building 

design 131. Metric-related documents published by the 

General Services Administration (GSA) include a federal standard listing preferred metric 

and inch-pound units and conversion values for use with those 

units [4], metric usage requirements in the Federal Acquisition Regulations [5], guidance on 

using metric units in federal product descriptions [6], 

guidance on preparing metric construction designs [7], and guidance on using metric units 

in federal information processing [8]. Documents have also 

been published by the Departments of Defense and Agriculture, as well as other agencies. In 

the private sector there are also many current and 

authoritative documents, including metric guidance for the manager [9], metric editorial 

guidance [10], metric construction guidance [11], and 

information on metric training materials [12]. Many of the above documents list other useful 

reference documents. 

IV. AGENCY ACTIONS 

A. When an agency implements preferred use of metric units, it should clearly define the 

policies, procedures,and conventions involved in its implementation. Common 

understanding of the agency's ground rules is key to successful implementation of 

change. 

B. Agencies should be sensitive to the level of transition of all parties affected by their 

planned actions, because many sectors of the economy will differ in their approach to 

and/or willingness to complete their transition to the use of metric units. Depending on 

the extent of the use of metric units by affected parties, an 

agency might: 

1. Use metric units as the primary units in all measurement-sensitive transactions. 

(For example, this would be done where an industry already uses metric units 

exclusively or has clearly indicated a decision to do so.); or 

2. Use, on an interim basis, both metric and inch-pound units while clearly 

indicating a policy of preferring metric units with timetables and processes to 

achieve metric only usage. (For example, this might be done where an agency's 

measurement-sensitive mission needs cannot be met fully using available metric 

products.) 

In those cases where the sole use of metric units would compromise good 

communication or other units have been specified as a contractual requirement, 

quantifies should be expressed in metric unit followed, in parentheses, by the same 

quantities expressed in the other units. Exceptions may sometimes be necessary for 

commercial devices, technical standards, or quantities having special legal 

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significance; examples include commercial weights and measures devices and the 

related laws and regulations. However, even in such cases, quantities expressed in 

metric units should be used whenever possible with the inch-pound units following in 

parentheses. 

C. Agencies should be aware that the acceptability of particular measurement units to a 

given industry or sector may not be apparent. Therefore, it is important to ensure 

adequate opportunity for comments by any affected industries, as well as the general 

public, on proposed changes in the measurement units to be used. Federal Register 

notices, press releases, or the like should be used for this purpose. 

D. Federal metric policy [1] specifically prescribes that agencies shall: 

1. Establish plans and dates for use of the metric system in procurements, grants 

and other business-related activities; 

2. Coordinate, through the ICMP, metric transition plans with other federal 

agencies, state and local governments, and the private sector, 

3. Require maximum practical use of metric units in areas where federal 

procurement and activity represents a predominant influence on industry 

standards (e.g., weapon systems or space exploration.) Strongly encourage 

metrication in industry standards where federal procurement and activity is not 

the predominant influence, consistent with the legal status of the metric system 

as the preferred system of weights and measures for United States trade and 

commerce;6 

4. Assist in resolving metric-related problems brought to the attention of the 

agency that are associated with agency actions, activities, or programs 

undertaken in compliance with these guidelines or other laws or regulations; 

5. Identify measurement-sensitive agency policies,procedures, regulations, 

standards, specifications, procurements, and legislative proposals and ensure 

that they are updated to remove barriers to transition to the metric system; 

6. Consider cost effects of metric use in setting agency policies, programs, and 

actions and determine criteria for the assessment of their economic feasibility. 

Such criteria should appropriately weigh both agency costs and national 

economic benefits related to changing to the use of metric units; 

7. Provide for full public involvement and timely information about significant 

metrication policies, programs, and actions; 

8. Seek out ways to increase understanding of the metric system of measurement 

through educational information and guidance and in agency publications; 

9. Consider, particularly, the effects of agency metric policies and practices on small 

business; and 

10. Consistent with the Federal Acquisition Regulation System (48 CFR), accept, 

without prejudice, products and services dimensioned in metric units when they 

are offered at competitive prices and meet the needs of the Government, and 

ensure that acquisition planning considers metric requirements. 

V. PRACTICAL AND MEANINGFUL MEASUREMENT EXPRESSIONS 

A. Whenever possible, federal agencies should use the units recommended in Federal 

Standard 376 141. Conversion factors, rounding, and other elements of metric system 

usage not listed in Federal Standard 376, or for units not covered in Federal Standard 

376, should be based on the latest editions of the reference documents listed in 

Federal Standard 376.7

B. Agencies may be able to benefit from the experience of 

counterpart agencies in other countries where the metric system has been recently 

adopted. For instance, many British and Canadian agencies have already resolved 

problems similar to those that may also arise in the U.S. Government's transition. 

C. Common sense, based on the knowledge and experience of the agency, should be the 

most important determinant in choosing practical and meaningful values, more 

precisely called "magnitudes," for the particular purposes involved, Many approaches 

can be used for selecting magnitudes in one measurement system in place of those of 

another. The following "approaches" are offered not as rules or restrictions, but to 

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illustrate factors agencies may need to consider:8

1. Exact Mathematical Conversion: This process is used to obtain an exact change 

in measurement units only -without altering the magnitude. The metric 

equivalent to an inch-pound magnitude is determined by multiplying by the 

appropriate conversion factor. The result is then normally rounded in a manner 

that reflects the precision of the original inch-pound value. In exact 

mathematical conversion, the primary concern is the necessary degree of 

precision. The new values should have the same degree of precision as that of 

the value from which the conversion is made. This approach produces what is 

referred to as "soft" metric conversion. 

2. Adaptive Conversion: This process changes a magnitude in one system to a 

magnitude in another that is reasonably equivalent. Above all, this process 

should result in conversions to magnitudes that are meaningful and practical in 

application.9 Judgments in this process are often subjective and may require 

balancing of competing interests, including magnitudes employed in international 

standards and practices in the same or similar areas of application. This 

approach comes closer to producing what is referred to as "hard" metric 

conversion. 

3. Size Substitution: In this approach an inch-pound standard size is replaced with 

an accepted metric standard size for a particular purpose. Size substitution might 

be used in taxing, selling, or packaging liquids by the liter -instead of by the pint 

or quart (as for milk), or instead of by the gallon (as for gasoline), or the choice 

of square meters instead of square yards (as for textiles). This is usually done to 

conform to international practice, that is, to adopt an internationally recognized 

standard or convention for trade and communication. This approach produces a 

"hard" metric conversion. 

D. Conversion of the values of quantities should be handled with careful regard to the 

implied correspondence between the accuracy of the data and the given number of 

digits. In all conversions, the number of significant digits retained should be such that 

accuracy is neither sacrificed nor exaggerated: Net content values on package labels 

are often shown in both inch-pound and metric units. The converted values, normally 

in parentheses, are often rounded to an appropriate degree of precision. The following 

table illustrates the above three approaches applied to the same inch-pound values:10

Nominal Value: 1lb11 5 lb 10 lb

Exact 

Mathematical 

Conversion:

454 g 2.27 kg 4.54 kg

Adaptive 

Conversion: 450 g 2.25 kg 4.5 kg

Size Substitution: 500 g 2.5 kg 5.0 kg

1. Net content values on package labels are often shown in both inch-pound and 

metric units. The converted values, normally in parentheses, are often rounded 

to an appropriate degree of precision. The following table illustrates the above 

three approaches applied to the same inch-pound values:10 

2. The speed limits on the nation's interstate highway network, 55 or 65 miles per 

hour (mph), is an exact magnitude imposed by law. A "Exact Mathematical 

Conversion' of 55 mph yields 88.514 kilometers per hour (km/h). "Adaptive 

Conversion" would yield 88 km/h (or the even more awkward magnitude of 88.5 

km/h). 'Size Substitution' yields the more practical speed limit of 90 km/h, as 

widely chosen in Canada. Similarly the 65 mph limit might become l00 km/h.

3. Contracts for drilling water wells might require sampling geologic materials at 

specific depth intervals, usually 10 feet Because these drilling depths are not 

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measured precisely (perhaps they vary by ± 1 ft), it would not seem practical to 

convert contract specifications to metric intervals of 3.05 meters. A practical and 

meaningful conversion for this purpose might be 3 meter intervals. 

4. A Federal Communications Commission rule included a requirement that "two 

new classes of stations, classes Cl and C2, with expected service ranges of 72 

kilometers (45 miles) and 52 kilometers (32 miles), respectively, will be allowed 

to operate in Zone II. " Note that instead of an exact mathematical conversion, a 

practical and meaningful "adaptive conversion" was chosen that satisfied the 

agency's purposes. 

5. A recommended regulation on liquid measurement adopted by the National 

Conference on Weight and Measures states: "On a retail device with a designed 

maximum discharge rate of 25 gallons per minute (100 L/min) or greater, the 

maximum and minimum discharge rates shall be marked on an exterior surface 

of the device and shall be visible after installation." A practical and meaningful 

"adaptive conversion" satisfied the agency's purposes, avoiding a more precise 

but less practical magnitude such as 96 L/min. 

6. The maximum truck body width allowed under the Surface Transportation 

Assistance Act of 1982 is 102 inches. A question arose as to whether trucks 

manufactured to the common European truck width of 2.6 meters (102.36 

inches) would be allowed on U.S. highways. Common sense prevailed over 

unnecessary precision in this ruling; the Federal Highway Administration 

determined the 2.6 meter truck width to be acceptable. . 

7. An EPA regulation specifies: "The sampling point for monitoring emissions shall 

be in the duct at the centroid of the cross section of the smoke stack if the cross 

sectional area is less than 50 ft2 (4.645 m 2) or at a point no closer to the wall 

than 3 ft (0.914 m) if the cross sectional area is 50 ft2 (4.645 m2) or more." In 

this case EPA chose "exact mathematical conversion," since comparability 

between new and historical data was desired. 

E. However, a practical and meaningful "adaptive conversion" might have produced: "The 

sampling point for monitoring emissions shall be in the duct at the centroid for smoke 

stacks having a radius <.1.2 m. For stacks >1.2 m the sampling point shall be at a 

point <92 cm from the stack wall." This would not have necessitated moving existing 

fixed measuring devices and would have allowed newly installed devices to collect 

samples in the same area of the smoke plume as devices installed under the inchpound regulation. 

F. Occasionally, product names may contain nominal dimensions. Such commercial 

designations are generally not true measurements and therefore should not be 

translated arbitrarily to metric units. For example, the "two by four," a nominal 

description of common lumber, is not actually 2 in. x 4 in. in cross section. Translation 

to precise metric units could therefore be misleading. 

VI. DATA REQUESTS, RECORDKEEPING, AND REPORTS 

It is often necessary to keep historical and current data comparable and consistent in 

precision, when some of the data are in inch-pound and some are in metric units. 

A. Reports and Questionnaires- Each agency should decide what units will be used in 

reports it generates or requires from the private sector. Whenever the agency receives 

data in one system of units but reports it in another, it is recommended that the 

agency assume the burden of making the needed conversion. When metric transition is 

underway, overlap periods may be allowed. Forms can be designed in a variety of 

ways to provide respondents with options as to which units they use. Dual columns, 

rows, or pages might be used when choice of units by the respondent is permitted. 

Alternative versions of the questionnaire (i.e., inch-pound and metric versions) might 

be provided 

B. Records - During a transition period from one measurement system to another, units 

from both systems must be accommodated. Agencies may encounter a wide variety of 

problems during such time and should plan how they will identify, co-mingle, convert, 

and ultimately standardize the recording of data. A typical problem arises in collecting 

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and storing temperature data. Where no decimal value has been used for data 

recorded in degrees Fahrenheit (e.g., 93 °F), reports in degrees Celsius might use 

increments of 0.5 °C to keep approximately the same degree of precision. This is 

warranted because the Celsius degree is 1.8 times larger than the Fahrenheit degree. 

(NOTE: An expression containing one digit to the right of the decimal point suggests 

an accuracy of at least ±0.1. Such precision is not intended in this case and should be 

disclaimed if necessary.) 

C. Recordkeeping -- ADP Considerations - Metric conversion, particularly during 

transition, may require computer software modifications. Special protocols may be 

needed to allow for the recording, processing, and display of information in the desired 

units. Also, the duration for maintaining dual units and any need to convert or provide 

conversion tables for historical data should be considered. Issues such as these should 

be coordinated by responsible ADP and/or statistical services personnel and the agency 

metric coordinator. The metric coordinator should be responsible for keeping all parties 

informed of proposed metric conversions in the agency. 

VII. ASSISTANCE 

Assistance in interpreting or implementing these recommendations, or in determining 

practical and meaningful metric values, is available from the Metric Program Office, U. S. 

Department of Commerce, National Institute of Standards and Technology, Room A146, 

Bldg. 411, Gaithersburg, MD 20899, telephone (301) 975-3690. Information on the status of 

metric conversion for a given industry sector might be obtained from relevant trade 

associations or the American National Metric Council (ANMC), 4340 East West Highway, 

Suite 401, Bethesda, MD 20814-2211 and/or the U.S. Metric Association, 10245 Andasol 

Ave., Northridge, CA 91325-1504. These organizations are involved in planning for the 

metric transition in the private sector. 

Footnotes

1 The 'modernized' metric system is known as the International System of Units or Si (from the 

French "Le Systeme International d'Unites," which is abbreviated SI), and which is interpreted or 

modified for use in the United States by the Secretary of Commerce (55 FR 52242, Dec. 20, 

1990). (See reference [1].)

2 Metric Conversion Act of 1975 (P.L. 94-168, 89 Stat. 1007; 15 U.S.C. 205 et seq, as amended 

by the Omnibus Trade Act of 1988, P. L. 100418.)

3 The ICMP is an interagency council chartered by the Secretary of Commerce under authority of 

EO 12770 (see reference [1]) whose members are senior policy officials representing 39 Federal 

Agencies that assist in formulating Federal metric policies, in consultation with the private sector.

4 A "measumment-sensitive" law, regulation, recordkeeping requirement or reporting requirement 

is one whose application or meaning depends substantially on some measured quantity (e.g., 

mandatory product or performance criteria or standards, such as emission levels, and/or size or 

weight limitations in shipping.) The mere presence of dimensions or measurement terms does not 

necessarily make an item "measurement sensitive."

5 The term 'inch-pound' units includes but is not limited to units based upon the inch and the 

pound commonly used in the United States. Note that "inch-pound" units having the same names 

in other countries may differ in magnitude.

6 Metric Conversion Act, sec 3(l).

7 Both the American National Standards Institute (ANSI) and the American Society for Testing and 

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Materials (ASTM), publish Metric Practice Standards, ANSI 268 and ASTM E380, respectively.

8 For more technical guidatwe concerning significant digits, precision, accuracy, and tolerances, 

refer to the appropriate national standards cited in Footnote 7.

9 Often overlooked in conversion is the need to allow for differences in the absolute size of the 

measurement units involved. For example, 36 inches would normally be converted to 91 

centimeters, not 91.44 centimeters, or to 914 millimeters, not 914.4 millimeters. For details see 

Fed. Std. 376 Section 4.5.

10 An exception to conventional rounding practices may be observed on certain grocery and other 

consumer items, where the converted quantity is rounded down to avoid overstatement of 

contents. This practice, which is still recommended by the National Conference on Weights and 

Measures, calls for dropping all digits of the converted quantity beyond the first three digits where 

converted metric units are also displayed. The Federal Trade Commission recommends and the 

Food and Drug Administration requires direct mathematical conversion with rounding procedures 

such as those set forth in Federal Standard 376.

11 The value "l lb" could conceivably be intended to represent 1, 1.0, 1.00, 1.000, or 1.0000 lb, or 

even greater accuracy, as might the 5 and 10 lb values. The converted value must be carried to a 

sufficient number of digits to maintain the accuracy implied or required in the original quantity.

12 40 CFR, Part 57.404(a)(3).

References

1. Interpretation of the SI and Metric Conversion Policy for Federal Agencies, NIST SP 814*, 

which includes: 

• Metric System of Measurement; Interpretation of the International System of 

Units for the United States, (55 FR 52242, Dec. 20, 1990); • Metric Conversion 

Policy for Federal Agencies, 15 CFR Part 1170; and • Metric Usage in Federal 

Government Programs, Executive Order 12770 of July 25, 1991 (56 FR 35801, 

July 29, 1991).

2. Guide for the Use of the International System of Units, The Modernized Metric System, NIST 

SP 8 1 1 *. 

3. Metrication in Building Design, Production, and Construction -- A Compendium of 10 Papers, 

NBS SP 530*. 

4. Preferred Metric Units for General Use by the Federal Government, Federal Standard 376. 

The current version, Fed Std 376B, dated January 27, 1993 is available from the General 

Services Administration, Specification Unit (WFSIS), Room 6039, 7th and D Streets, S.W., 

Washington, DC 20407.

5. Specifications, Standards, and Other Purchase Descriptions,10(10.02) Federal Acquisition 

Regulation System (48 CFR), FAC 90-4, April 15, 1991. 

6. Use of Metric System Measurement in Federal Product Descriptions, GSA Federal Property 

Management Regulation (FPMR), Final Rule, 41 CFR Part 101-29. 

7. Metric Design Guide, 2nd Edition, GSA Office of Design and Construction, April 1992. 

8. Use of Metric Measures in FIP Acquisitions, GSA Federal Information Resources Management 

Regulation (FIRMR), Bulletin C-31, January 2, 1992. 

9. Metrication for the Manager, 2nd Edition, John T. Benedict, co-published by: Society of 

Automotive Engineers, Inc., 400 Commonwealth Drive, Warrendale, PA 15096-0001 and 

American National Metric Council, 4340 East West Highway, Suite 401, Bethesda, MD 20814-

4411 

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10. Metric Editorial Guide, American National Metric Council, 4340 East West Highway, Suite 

401, Bethesda, MD 20814-4411 

11. Metric Guide for Federal Construction, National Institute of Building Sciences, 1201 Street N.

W., Washington, DC 20005 

12. Freeman Training/Education Metric Materials List U.S. Metric Association, 10245 Andasol 

Ave., Northridge, CA 91325 

*Available from the National Technical Information Service, 5285 Port Royal Rd., Springfield, 

VA 22161 

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