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Legal Metrology Devices Program


The Legal Metrology Devices Program (LMDP) promotes uniformity at the international, federal, state, and local levels in standards and practices for weighing and measuring devices to facilitate trade and protect U.S. businesses and citizens. To accomplish this task, the LMDP collaborates with and provides technical assistance to the National Conference on Weights and Measures (NCWM) and other organizations, working to develop standards for weighing and measuring devices, test procedures, and guidelines and interpretations, including those that are developed and published by NIST. The LMDP Program provides technical support to the NCWM National Type Evaluation Program (NTEP) for the evaluation of commercial weighing and measuring equipment to determine compliance with NIST handbooks. Many members of the program also serve as the U.S. technical points of contact or secretariats for international standards such as those issued by the International Organization of Legal Metrology (OIML); in this capacity, LMDP staff are responsible for developing U.S. positions and suggesting changes to international and domestic voluntary weights and measures standards to promote harmonization and eliminate technical barriers to trade.

Additionally, the LMDP provides training, technical assistance, and guidance to industry and weights and measures officials and continually assesses and responds to the needs of its customers for new weights and measures standards and practices by developing, and disseminating:

  • Examination procedures for weighing and measuring devices;
  • Training materials and programs;
  • Technical interpretations and guidance on issues related to commercial weighing and measuring devices;
  • Technical portions of legal standards and codes for commercial measurement devices and testing equipment; and
  • Solutions for complex technical legal metrology issues

What is Legal Metrology?

Legal Metrology is the practice and process of applying regulatory structure and enforcement to metrology.

What is a "Legal Metrology Device"?

In the scope of the LMDP's work, a “legal metrology device” refers to a weighing or measuring device that is used to determine a quantity on which a charge is based for goods or service. It also refers to devices such as those used for law enforcement purposes such as scales used for highway weight enforcement. “Legal metrology devices” are often referred to as “commercial” weighing and measuring devices. The types of devices addressed by the LMDP are divided into the broad categories of “Weighing Devices” (which include devices such as deli scales, jewelers and prescription balances, and vehicle scales); “Measuring Devices” (which include devices such as retail motor-fuel dispensers or gas pumps, vehicle mounted meters for delivering home heating oil, and liquefied petroleum gas liquid-ing devices for delivering commercial propane to homes and businesses); and “Other Device Types” (which include devices such as grain moisture meters, taximeters, and multiple dimension measuring devices).

Who We Are

The Legal Metrology Devices Program staff members are legal metrologists with experience working as weights and measures officials, weighing and measuring device type evaluators, and/or industry service specialists. LMDP staff members have served and continue to serve as technical advisors to committees and work groups such as the NCWM Specifications and Tolerances Committee (the NCWM Committee charged with reviewing proposed changes to NIST Handbook 44) and the technical sectors of the National Type Evaluation Program. LMDP staff members have also worked with the weights and measures community to develop test procedures, field manuals, and other documents to assist field officials in applying the requirements of NIST Handbook 44. Staff members are also experienced trainers who have conducted many classes, seminars, and presentations related to the inspection and testing of commercial weighing and measuring equipment, with the goal of improving uniformity in the application of weights and measures standards and practices.


Retail Motor Fuel Dispenser Training Video

See the NEW video demonstrating the minimum tests of a retail motor fuel dispenser (gasoline pump) in accordance with NIST Handbook 44. Short videos are also available for each of the tests that are included in the full length video by clicking on the link below.

Retail Motor Fuel Dispenser Short Training Videos:

  • Selecting & Maintaining the Test Standard,
  • Wetting the Standard,
  • Normal & Slow Flow Test,
  • Leveling,
  • Reading the Meniscus,
  • Draining A Test Measure or Prover, and
  • Anti-Drain Test

General Information:
301-975-4004 Telephone
301-975-8091 Facsimile

100 Bureau Drive, M/S 2601
Gaithersburg, MD 20899-2601