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Mass and Force Group


The Mass and Force (MF) Group in the Quantum Measurement Division (QMD) of the Physical Measurement Laboratory (PML) at the National Institute of Standards and Technology (NIST):

  • Provides high-accuracy physical measurement test and calibration services, and access to the top of the traceability chain for the SI units of mass and force to meet the needs and demands of U.S. industry, government, and the scientific community, and to improve public health and welfare.
  • Provides appropriate leadership and input to embody strong representation of U.S. interests and technology at national, regional, and international standards organizations in the fields of mass and force metrology.
  • Carries out research and development and provides technical support in measurement science, instrumentation design, development, and testing to develop new physical measurement services, new realization of the units, new transfer standards, new methods and data, custom tests, and consulting for mass and force metrology to improve NIST capabilities for accomplishing the first two items above to meet the needs and demands of U.S. industry, government, and the scientific community and to improve public health and welfare.
  • Provides technical support for legal metrology and to assist industry with the characterization of force transducers used in discrete parts manufacturing.

deadweight machine images
Deadweight machine images


Quantifying the environmental contributions to mass change—Since the inception of the SI system of units, physical mass artifacts have been transferred and exchanged in order to disseminate the kilogram. The kilogram is essential to a broad range of …

SI-traceable Dynamic Force—Established calibration methods for force transducers are static, with a known constant force applied to the transducer and compared to the transducer indication. However many force measurements …

Small Mass and Small Force Metrology at NIST—There are two projects: The electronic milligram; and NIST-on-a-chip optomechanical methods for calibration of mass, force, laser power and other quantities.

Calibration of Force Transducers—NIST provides calibration services for force-measuring devices by applying known forces, either tension or compression, to the elastic device and recording the sensed deformation. Most calibrated …

National Type Evaluation Program (NTEP)—The NTEP program is administered through the National Conference on Weights and Measures (NCWM).

NIST Mise en Pratique of the New Kilogram Definition—As part of a New SI system of units to be adopted in 2018, the kilogram will be redefined so that it may be realized in terms of Planck’s constant. By experimental necessity, this new realization …

Calibration of Mass Standards—NIST maintains the national standard for mass in the form of the prototype kilograms (K4, K20, K79, K92, and K102) and provides services to support the parts of the national measurement system that …

Reconditioning of the 4.45 MN deadweight machine—Physical disassembly of the 4.45 MN (1,000,000 lbf) deadweight machine (DWM) began in FY15 in order to address material galling that developed in key structural components within the stainless …

  • U.S. National Prototype Kilogram

    U.S. National Prototype Kilogram. (© Robert Rathe)

    The National Prototype Kilogram (shown at right) is made of 90% platinum and 10% iridium. It was assigned to the United States in 1889 and is periodically re-certified and traceable to "The International Prototype Kilogram" held at BIPM near Paris.


Physical Measurement Laboratory (PML)
Quantum Measurement Division

Mass and Force Group (684.07)
Dr. Zeina J. Kubarych, Leader

General Information:
301-975-6624 Telephone
301-417-0514 Facsimile

100 Bureau Drive, M/S 8221
Gaithersburg, Maryland 20899-8221