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.
Metric Act of 1866 (14 Stat 339) PDF legalized the use of the Metric System in the U.S. The law was amended by the America Competes Act of 2007 PDF (U.S. Public Law 110-69), replacing the old metric system definition with the International System of Units (SI)
Metric Conversion Act of 1975 (15 U.S.C. 205a et seq.) amended by the Omnibus Trade and Competitiveness Act of 1988, which declares the metric system as the preferred measurement system for U.S. trade and commerce.
Federal Acquisition Regulation System (FAR), 7.103(o) – Ensuring that agency planners include use of the metric system of measurement in proposed acquisitions 15 U.S.C. 205b (See 11.002(b)) and agency metric plans and guidelines
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
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
NIST SP 814 - Interpretation of the SI for the United States and Metric Conversion Policy for Federal Agencies (1998)
NIST IR 4855 - Recommended Agency Procedures for Implementing Federal Metric Policy (1992)
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.
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.
Announcement: Federal and State Measurement Unit Change
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.