NPL provides the basic backbone of organizational structure for metrology in India. NPL is
the custodian of national measurement standards for physical measurement in the country. This
premier national laboratory is established with the objective to strengthen and advance physics-
oriented research for the overall development of science and technology in the country. NPL has
the responsibility of physical measurements based on the International system (SI units) under the
subordinate legislation of Weights and Measures Act 1956 (reissued in 1988 under the 1976 Act).
NPL also has the statutory obligation to establish, maintain and update the national standards of
measurement and calibration facilities for different parameters. NPL maintains seven SI base
units, viz., meter, kilogram, second, kelvin, ampere, candela, mole (mol) and the SI supplementary
units radian (rad) and steradians (sr).
The main objectives of the NPL’s work are as follows :
— To establish, maintain and improve continuously the national standards for measure-
ments for the benefit of the country and also to realize the units based on International
— To determine the major physical constants,
— To develop and evaluate measurement techniques,
— To assist industries, governmental and other agencies in their developmental task by
precision measurements, calibration and development of devices and processes related
— Laboratory’s commitment to good professional practice and quality of its calibration and
testing in serving to industry, and
— Technical advisory services, information, extension, consultancy and training and
collaboration with universities and other organization.
Under the Standards of Weights and Measures Rules 1988, the NPL has been further
assigned the obligation to act as the custodian of the national standards of measurement (excepting
those for ionizing radiations) compatible and traceable to the International System (SI units). The
NPL fulfils this responsibility by developing, maintaining and updating of these standards through
interaction and metrological intercomparison with other major standards laboratories in the NPL
(UK), NIST (USA), WNIFTRI (Russia), PTB (Germany), IMGC (Italy), BIPM (France), ETL (Japan),
NIM (China), CSIR (Australia), DSIR (New Zealand), NRC (Canada) and, directory of National
Measurement Systems of Nori-Aligned (NAM) Countries and other Developing Countries.
The NPL represents India in the Bureau of International Weights and Measures (BIPM),
General Conference on Weights and Measures (CGPM) and International Committee for Weights
and Measures (CIPM) besides several other international committees in the area of acoustics and
vibration, time and frequency, vacuum and pressure, temperature, humidity and other parameters
The nodal work done by the NPL in metrication of the entire measurement system of the
Country since 1956 forms the basis of legal metrology function in the country coordinated by the
Directorate of Weights and Measures (DWM) Govt, of India. Measurement standards, calibration
service, specialized testing back-up, technical advisory consultancy services and participation in
the committees of the DWM form the bulk of NPL support for these important areas of consumer
scientific knowledge, protection and improvement and securing of the living conditions.
The principal activities of the NPL in the field of metrology include the development of:
— Physicso-mechanical standards : length standards and dimensional metrology, mass,
volume and viscosity, fluid flow measurement, standards of force and hardness, pres-
sure/vacuum, temperature, optical radiation, ultraviolet radiation, infrared radiation,
acoustics and ultrasonic.
— Electrical standards : dc measurement, Josephson voltage, ac standards and standards
of LF and HF impedance, magnetic standards, HF, MW voltage, current power, HF, MW
attenuation and impedance standards.
— Other standards: Time and frequency, NABL programme, piezoelectric accelerometer,
— Calibration and Testing Service Programme,
— Reference material standards, and
— Participation in international metrology activities.
Role of National Physical Laboratory (NPL) in Metrology (Metrology)