metrology

Metrology is the science, theory, and practice of measurement. It encompasses the development and realization of measurement units, the specification of measurement methods, the calibration of instruments, and the assessment of measurement uncertainty. Metrology aims to ensure that measurements are accurate, reproducible, and internationally comparable, enabling commerce, science, and technology to function reliably across borders.

The field is commonly divided into scientific metrology, industrial metrology, and legal metrology. Scientific metrology develops new measurement techniques and realizes the SI units through primary standards and reference materials. Industrial metrology applies and maintains measurement equipment in manufacturing and quality control to ensure product conformity. Legal metrology encompasses laws and regulations governing measurements used in trade, health, safety, and the environment, enforcing fairness and protection for consumers.

Measurements are anchored to the International System of Units (SI) via a chain of metrological traceability, usually through national metrology institutes and accredited calibration laboratories. The global metrology system is coordinated by the International Bureau of Weights and Measures (BIPM) and supported by international standards bodies such as ISO and IEC. Measurement results are accompanied by an uncertainty estimate and must meet established metrological requirements.

Applications span science, engineering, industry, healthcare, environmental monitoring, and commerce. Core activities include instrument calibration, instrument qualification, reference materials, proficiency testing, and the development of measurement standards. Metrology underpins innovation by providing reliable data and comparability across time and space.