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Laboratory Metrology

Ensuring traceability of state weights and measures standards to the International System of Units (SI) through NIST standards and measurement services.

Laboratory Metrology Banner
Credit: NIST

About Laboratory Metrology

The Laboratory Metrology group within OWM has the primary responsibility of ensuring SI traceability for the State legal metrology laboratory programs across the U.S. through International Accreditors for Continuing Education and Training (IACET) accredited training and State laboratory recognition program and accreditation efforts. We work closely with the other groups in OWM and legal standard development organizations to maintain and develop documentary standards, practices, and technical guidance related to the calibration workload of the State laboratories

Who We Are

Staff members are physical scientists, laboratory metrologists, and program administrators with experience working in State and Federal metrology laboratories and as weights and measures officials. 

What We Do

State legal metrology laboratories are custodians at the State level of measurement standards that serve as the basis for ensuring equity in the marketplace and as reference standards for calibration services for US industry. The Laboratory Metrology group provides metrology training for a wide range of metrology stakeholders – including State laboratory metrologists, State and local weights and measures officials, representatives for the commercial weights and measures industry and federal metrology laboratories, and metrologists from other National Metrology Institutes and Designated Institutes across the globe. As part of its program to encourage a high degree of technical and professional competence in such activities, NIST OWM has developed performance standards and formalized procedures for recognition of  State legal metrology laboratories on a voluntary basis. Certificates of Metrological Traceability are issued upon evaluation of the laboratory's ability to make reliable metrological measurements (principally mass, volume, length, and temperature). 

OWM’s Laboratory Metrology group effort also provides metrology training through six formalRegional Measurement Assurance Program (RMAP) groups as shown in this map:


The RMAPS include the Caribbean Measurement Assurance Program (CaMAP), the Southwestern Assurance Program (SWAP), the Southeastern Measurement Assurance Program (SEMAP), the Northeastern Measurement Assurance Program (NEMAP), the MidAmerica Measurement Assurance Program (MidMAP), and the Western Regional Assurance Program (WRAP). Participants include State and local weights and measures laboratories and the U.S. Department of Agriculture, Grain Inspection Packers and Stockyards Administration (USDA-GIPSA).

The Laboratory Metrology group operates an ISO 17043 compliant proficiency testing (PT) program that assesses the effectiveness of the group’s metrology training efforts for the State laboratory participants and the traceability of the State metrology laboratories to the SI through NIST. The PT program’s artifacts maintain traceable calibrations to the SI through NIST. Participants of the group’s PT program include federal and commercial laboratories across the U.S., in addition to State legal metrology laboratories. 

NIST Resources for Laboratory Metrology

  1. Calibration Services
  2. Engineering Metrology Toolbox
  3. Fluid Flow Group (& Volume)
  4. Laboratory Accreditation Program/NVLAP
  5. Length
  6. Mass and Force Group
  7. SI Units, Uncertainties
  8. Statistical Engineering, Electronic Statistics Handbook
  9. Thermometry and Humidity
  10. Traceability Resources
  11. Weights and Measures Publications

What is Legal Metrology?

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


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