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Metric Policy

Image of the Metric Act of 1866
Metric Act of 1866, also known as the Kasson Act
Credit: National Archives

The U.S. Congress has established a national policy of increasing the voluntary use of the metric system as the preferred system of measurement for trade and commerce in the United States. It is this national policy that places the decision and pace of metric use in the hands of individual companies, organizations, and persons. Currently, U.S. law permits the use of either the SI (International System of Units) or the U.S. customary measurement system. Although NIST is a non-regulatory agency, the adoption of SI practices is encouraged whenever possible. Explore Metrication in Law and U.S. Metrication Frequently Asked Questions to learn more.

U.S. Metric System (SI) Legal Resources

Diplomatic Treaties

The Convention of the Meter Signed in Paris in May 20, 1875 by seventeen countries, including the United States. May 20th is now celebrated as "World Metrology Day"


Federal Policies and Regulations

Federal Agency Metric Transition

White Image of Capitol Building on blue background
Credit: Pixabay

The Metric Program coordinates metric transition activities under the Metric Conversion Act, including transition of all federal agencies (Executive Order 12770). U.S. metric legislation and policy authorizes the Secretary of Commerce to direct and coordinate the federal agency metric transition and to assess progress. Federal agencies implement formal policy and plans for using the SI (metric system) and report transition progress. The use of the SI in federal agency programs relating to trade, industry, and commerce is intended to support industry's voluntary adoption of the SI.

The Executive Order and the Metric Conversion Law designates the SI (metric system) of measurement as the preferred system of weights and measures for use in trade and commerce, and requires the use of the SI system, to the extent economically feasible, by each federal agency and department in its procurements, grants, and other business-related activities. Metric usage is not required if its use is impractical or is likely to cause significant inefficiencies or loss of markets to United States firms. Guidance on implementation of Federal Government Metric Conversion Policy can be found in NIST SP 814.

Federal agencies and departments are required to formulate transition plans and to communicate them to the Metric Program at NIST. Heads of departments and agencies must establish effective process for a policy and program level review of proposed exceptions to metric usage, as well as to take initiatives to increase use of SI in industry, and seek out ways to increase understanding of the metric system of measurement through educational information and guidance and in government publications.

Progress Report Guidelines

Screen shot of page 1 of FY2022 Annual Metric Progress Report Guidelines


  • Annual Metric Progress Report Guidelines (FY2023) PDF - Deadline: May 1, 2024
  • Annual Metric Progress Report Guidelines (FY2022) PDF - Deadline: May 1, 2023
  • Annual Metric Progress Report Guidelines (FY2021) PDF - Deadline: May 1, 2022
  • Annual Metric Progress Report Guidelines (FY2020) PDF - Deadline: May 1, 2021
  • Annual Metric Progress Report Guidelines (FY2019) PDF - Deadline: May 1, 2020

Federal Agency Metric Policy Implementation Examples

General Services Administration

National Institutes of Health


  • Architect-Engineer Information Center Metrication. It is Smithsonian policy to express weights and measures in metric system numbers to the extent possible in documents for public viewing, grant and contract solicitations and awards, exhibition signage, and public presentations. When directors of museums, research centers, and offices deem it to be more practical, weights and measures may be cited in written materials in traditional terms first, followed immediately by the metric measure equivalent in parentheses. Directors of Project Management and Engineering Design and Construction Divisions may determine the measurement system to be used on a project-by project basis, with appropriate documentation of the decision.
  • Smithsonian Directive 111, Metrication. This directive affirms the Smithsonian Institution’s commitment to integrating the metric system into the daily operations of the Institution as well as into its exhibitions and educational and other public programs.

Occupational Safety and Health Administration

USAID Acquisition and Assistance Policy

United States Patent and Trade Office

  • Use of Metric System of Measurements in Patent Applications (1992)
  • Manual of Patent Examining Procedure. Chapter 600, Section 608.
    • 608.01 Specification. Use of Metric System of Measurements in Patent Applications. In order to minimize the necessity in the future for converting dimensions given in the English system of measurements to the metric system of measurements when using printed patens as research and prior art search documents, all patent applicants should use the metric (S.I.) units followed by the equivalent English units when describing their inventions in the specifications of patent applications.

Veteran Affairs

Announcement:  Federal and State Measurement Unit Change

U.S. Survey Foot is obsolete
The U.S. survey foot is obsolete. Only use for historical and legacy applications.
Credit: NIST

In collaboration, National Oceanic and Atmospheric Administration (NOAA) and NIST have taken action to provide national uniformity in the measurement of length. The final decision to retire the U.S. survey foot was published in the Federal Register (October 5, 2020) announcing the deprecation date of December 31, 2022.

  • Beginning on January 1, 2023, the U.S. survey foot should not be used and will be superseded by the international foot definition (i.e., 1 foot = 0.3048 meter exactly) in all applications. Either the term foot or international foot may be used, as required for clarity in technical applications.
  • The preferred measurement unit of length is the meter (m) and surveyors, map makers, and engineers are encouraged to adopt the International System of Units (SI) for their work.
  • Although the SI is the preferred measurement system for trade and commerce in the United States, trade practice may continue to use non-SI measurement units, such as the U.S. customary system of measurement. The relationship between SI length measurement units and the U.S. survey foot and associated non-SI units published in the FRN will be incorporated in the upcoming edition of NIST Special Publication (SP) 811, Guide for the Use of the International System of Units (SI).
  • Updating state statutes is an important part of the implementation process. The National Society of Professional Surveyors (NSPS), American Association for Geodetic Surveying (AAGS), and NOAA National Geodetic Survey (NGS) have collaborated to create template legislation to aid state adoption and transition to the international foot. State government stakeholders are encouraged to review and customize the language, as needed. These legislative resources also include statutory text that has already been proposed or enacted by states.
  • FR DOC 2020 FR 21902 (Published October 5, 2020) - Deprecation of the United States (U.S.) Survey Foot.


Created November 4, 2009, Updated July 19, 2024