The end of World War II marked a pivotal point for industrial measurement science, or metrology. The unprecedented technological advancements of the war, from the development of jet engines and rockets to the atomic bomb, exposed a critical need for more rigorous measurement and calibration practices. 
A NIST engineer holding one of the agency's kilogram samples dubbed K92. Credit: NIST
Complex new devices could not be reliably manufactured, maintained, or operated without precise measurements and standards.
In the post-WWII era, nations around the world began to formalize metrology programs to ensure that instruments and measurements were accurate, consistent, and traceable to fundamental units. From its early pioneers through the formation of international frameworks and unification of standards, metrologists have shown that excellence in calibration can be, quite literally, a matter of life and death.
WWII Technology and the Calibration Imperative
The second world war spurred incredible innovations that pushed the limits of measurement. The end of World War II marked the formal emergence of metrology as a distinct scientific discipline.
Specifically, three technological advances were responsible: the atom bomb, the jet engine, and rockets. Manufacturing these products required access to the best measurement capabilities of the time; errors in calibration would lead to defective products.
In the war’s aftermath, the focus shifted from developing prototypes to mass-production for defense and civilian use. This demanded rigorous tool and instrument calibration at levels not previously required. Even a minor measurement error in machining a jet turbine blade or mixing rocket fuel components could trigger catastrophic failure. Thus, in the 1940s and 1950s, militaries and industries established formal calibration programs to control quality and safety.
The U.S. military, for example, recognized the need for improved measurement reliability in its guided missile program in 1955. Metrology was becoming its own discipline, underpinning the era’s high-stakes engineering feats.
Early Pioneers and “Measurement Reliability”
Pioneers like Jerry Hayes of the U.S. Naval Ordnance Laboratory — often hailed as the “father of modern metrology” — soon stepped onto the scene. Hayes was trained as a nuclear bomb technician and served at Sandia National Labs. He was asked to figure out why the Navy and the factory were getting different test results and ultimately identified that instruments weren’t being properly calibrated during the manufacturing process. In response, Hayes formalized a calibration program for test equipment, and the Navy Metrology Engineering Center was born. 
Jerry Hayes. Credit: US Navy
Hayes eventually authored a seminal technical memorandum titled “Factors Affecting Measurement Reliability.” In the memo, dated 24 October 1955, Hayes advocated for implementing calibration programs and established fundamental requirements for them. Hayes’ work built upon previous statistical quality concepts (such as Alan Eagle’s risk-based methods) to formalize how calibration accuracy ratios and decision risks should be managed in a calibration system.
In essence, Hayes and his contemporaries established that properly calibrated equipment (and calibration intervals) is essential to making reliable measurements. These ideas were soon adopted as policy in the U.S. Navy and eventually echoed in military and industrial standards worldwide. Throughout the late 1950s and 1960s, national metrology centers and conferences (like the National Conference of Standards Laboratories, founded 1961) sprang up, spreading best calibration practices.
The influence of these early efforts endures, and it’s possible to trace elements of Hayes’ 1955 recommendations in modern requirements for calibration labs and quality systems.
Building a Global Metrology Infrastructure
In parallel with these technical advances, the institutional framework of global metrology was being constructed. Various nations realized that to support scientific progress and trade, they needed common measurement references and standards.
The International Organization for Standardization (ISO) was founded in 1947 to globally unify standards development. At the same time, the Bureau International des Poids et Mesures (BIPM), originally established by the 1875 Treaty of the Metre, continued its mission of maintaining fundamental units and reference standards for the world. The post-war period saw the formal adoption of the Système International d’Unités (SI) in 1960, creating a coherent set of base units (meter, kilogram, second, etc.) to which all calibrations should ultimately trace back to.
Critically, the concept of metrological traceability gained prominence. According to the International Vocabulary of Metrology (VIM) metrological traceability is the “property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty”.
In practice, this means any measurement should be linked via calibrations (perhaps through a chain of reference gauges and standards) all the way to the primary realization of the unit. Traceability ensures that measurements performed in different labs or countries are comparable.
Conclusion
From the crucible of WWII technology, modern metrology emerged as an indispensable discipline in support of innovation, safety, and international trade. Early visionaries like Jerry Hayes laid the groundwork by insisting on formal calibration programs and reliable measurement processes. In the following decades, the world established common foundations — the SI units, standards organizations like ISO, and oversight networks like BIPM, ILAC, and CIPM — to ensure measurements mean the same thing everywhere.
The consolidation of disparate national standards into ISO/IEC 17025 symbolizes how far we’ve come toward a unified global approach. Yet, the occasional catastrophe or audit finding due to poor calibration reminds us that metrology is not just academic idealism; it has immediate, real-world impact.
Metrological traceability and adherence to standards are what keep our airplanes flying safely, our factories producing quality goods, and our economies trading smoothly. The post-WWII evolution of metrology is a story of increasing rigor and cooperation, a journey still ongoing as technology advances and the world grows even more interconnected