Metrology News

Metrology Atlas resource library opens with the NIST GLP/SOP series The Metrology Atlas document library is live. The opening collection carries the NIST Office of Weights and Measures Good Laboratory Practic... Jul 31, 2026 Unified search now spans documents, definitions, standards and Q&A Search on Metrology Atlas now queries a single unified index covering the document library (page by page), the metrology dictionary, the sta... Jul 29, 2026 The 2019 SI redefinition, in practice: what changed for calibration laboratories Since 20 May 2019, all seven SI base units have been defined by fixing the numerical values of seven constants — the Planck constant now def... Jul 25, 2026 What your En number actually says — and what it does not Proficiency testing results for calibration laboratories usually arrive as an En number: the difference between your result and the referenc... Jul 22, 2026 Decision rules under ISO/IEC 17025:2017: guard banding moves mainstream The 2017 revision of ISO/IEC 17025 made decision rules explicit: whenever a laboratory states conformity, the rule that accounts for measure... Jul 21, 2026 ITS-90 in practice — and what the 2019 kelvin redefinition did not change Ask a calibration laboratory how it measures temperature and the honest answer is: against a scale, not a definition. The International Temp... Jul 19, 2026 Digital calibration certificates gather momentum The digital calibration certificate (DCC) — a machine-readable, cryptographically signed XML format pioneered by PTB and partners — continue... Jul 17, 2026 How to read a scope of accreditation before you buy a calibration An ISO/IEC 17025 accreditation logo on a website tells you a laboratory is accredited for something. Whether it is accredited for YOUR measu... Jul 13, 2026 A map of the GUM family: which uncertainty document answers which question 'The GUM' is shorthand for a whole family of JCGM documents, and knowing which member answers which question saves real time. JCGM 100:2008... Jul 8, 2026 150 years of the Metre Convention On 20 May 1875, seventeen states signed the Metre Convention in Paris, creating the International Bureau of Weights and Measures (BIPM) and... Jul 3, 2026 The Kibble balance: weighing mass against the Planck constant When the kilogram was redefined in 2019, the artifact in Sèvres gave way to a fixed numerical value of the Planck constant. The instrument t... Jun 27, 2026 Redefining the second: the road from cesium to optical clocks Since 1967 the SI second has been defined by a microwave transition in cesium-133. It is the most precisely realized unit in all of measurem... Jun 21, 2026 The VIM's fourth edition: what's changing in metrology's vocabulary The International Vocabulary of Metrology — the VIM — is the document that decides what words like calibration, traceability and uncertainty... Jun 16, 2026