| BEV/E+E | E+E Elektronik GMBH | Austria |
| EAA | Umweltbundesamt GmbH | Austria |
| SCK-CEN/LNK | Nuclear Calibration Laboratory, Belgian Nuclear Research Centre | Belgium |
| LABSAGAS | KJKP Sarajevogas d.o.o. Sarajevo | Bosnia and Herzegovina |
| IW | Institut za vode d.o.o. Bijeljina | Bosnia and Herzegovina |
| HMI/FSB-LPM | Laboratory for Process Measurements | Croatia |
| HMI/FER-PEL | Faculty of Electrical Engineering and Computing - Primary Electromagnetic Laboratory | Croatia |
| HMI/FSB-LIMS | Faculty of Mechanical Engineering and Naval Architecture - Laboratory for Testing of Mechanical ... | Croatia |
| HMI/FSB-LPMD | FSB-Laboratory for Precise Measurements of Length | Croatia |
| HMI/IRB-SSDL | Secondary Standard Dosimetry Laboratory of the Ruder Boskovic Institute | Croatia |
| HMI/DHMZ-SOUL | Meteorological and Hydrological Service | Croatia |
| ÚFE/IPE | Institute of Photonics and Electronics | Czech Republic |
| VÚGTK | Research Institute of Geodesy, Topography and Cartography | Czech Republic |
| CHMI | Czech Hydrometeorological Institute | Czech Republic |
| BKSV-DPLA | Brüel&Kjaer Sound & Vibration Measurement Ltd.-Danish Primary Laboratory for Acoustics | Denmark |
| TRESCAL | Trescal Ltd. | Denmark |
| DTI | Danish Technological Institute | Denmark |
| FORCE | FORCE Technology | Denmark |
| DTU | Technical University of Denmark | Denmark |
| UT | University of Tartu | Estonia |
| FGI-GG | Finnish Geospatial Research Institute | Finland |
| MIKES-FMI | MIKES-FMI Standard Laboratory | Finland |
| Aalto | Aalto University, Metrology Research Institute | Finland |
| STUK | Radiation and Nuclear Safety Authority | Finland |
| MIKES-SYKE | Finnish Environment Institute | Finland |
| LNE-CETIAT | Centre Technique des Industries Aérauliques et Thermiques | France |
| LNE-LTFB | Laboratoire Temps Fréquence de Besançon | France |
| LNE-INM | Institut National de Métrologie/Conservatoire National des Arts et Métiers | France |
| LNE-LNHB | Laboratoire National Henri Becquerel/Commissariat à l'Energie Atomique | France |
| LNE-SYRTE | Systèmes de Référence Temps - Observatoire de Paris | France |
| LNE-LADG | Laboratoire Associé de Débitmétrie Gazeuse | France |
| LNE-ENSAM | Ecole National Supérieure d'Arts et Métiers de Paris | France |
| LNE-IRSN | Institut de Radioprotection et de Sûreté Nucléaire | France |
| LNE-TRAPIL | LNE-TRAPIL | France |
| BAM | Bundesanstalt für Materialforschung und -prüfung | Germany |
| UBA | Umweltbundesamt | Germany |
| BVL | Bundesamt für Verbraucherschutz und Lebensmittelsicherheit | Germany |
| EXHM/GSCL-EIM | National Laboratory of Chemical Metrology/General Chemical State Laboratory - Hellenic Institute of ... | Greece |
| IRCL/GAEC-EIM | Ionizing Calibration Laboratory/Greek Atomic Commission - Helenic Institute of Metrology | Greece |
| ENEA-INMRI | Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti | Italy |
| VMC | Vilnius Metrology Centre | Lithuania |
| LEI | Lithuanian Energy Institute | Lithuania |
| LGUL | Laboratory of Geophysics of the University of Luxembourg | Luxembourg |
| NRPA | Norwegian Radiation Protection Authority | Norway |
| NILU | Norsk Institutt for Luftforskning | Norway |
| NIVA | Norwegian Institute for Water Research | Norway |
| INTiBS | Institute of Low Temperature and Structure Research | Poland |
| POLATOM | National Centre for Nuclear Research - Radioisotope Centre POLATOM | Poland |
| IST/LPSR | Laboratory for Radiation Protection and Safety | Portugal |
| IFIN-HH | Horia Hulubei National Institute of R&D for Physics and Nuclear Engineering | Romania |
| VINS | Vinča Institute of Nuclear Sciences | Serbia |
| MIRS/UL-FE/LMK | Metrology Institute of the Republic of Slovenia/University of Ljubljana-Faculty of Electrical ... | Slovenia |
| MIRS/UM-FS/LTM | Metrology Institute of the Republic of Slovenia/University of Maribor-Faculty of Mechanical ... | Slovenia |
| MIRS/SIQ/Metrology | Slovenian Institute of Quality and Metrology | Slovenia |
| MIRS/NIB/FITO | Metrology Institute of the Republic of Slovenia/National Institute of Biology/Department of ... | Slovenia |
| MIRS/IJS/F-2,O-2 | Metrology Institute of the Republic of Slovenia/Jozef Stefan Institute/Low and Medium Energy Physics ... | Slovenia |
| MIRS/IMT/LMT | Metrology Institute of the Republic of Slovenia/Institute of Metals and Technology/Laboratory of ... | Slovenia |
| MIRS/KI/L05 | Metrology Institute of the Republic of Slovenia/National Institute of Chemistry Slovenia/Laboratory ... | Slovenia |
| MIRS/ZAG/SM 480 | Metrology Institute of the Republic of Slovenia/Slovenian National Building and Civil Engineering ... | Slovenia |
| MIRS/UP-ZRS/LPOO | Metrology Institute of the Republic of Slovenia/University of Primorska, Science and Research Centre ... | Slovenia |
| ROA | Real Instituto y Observatorio de la Armada | Spain |
| IO-CSIC | Instituto de Óptica Daza de Valdés | Spain |
| ISCIII | Instituto de Salud Carlos III | Spain |
| INTA | Instituto Nacional de Técnica Aeroespacial | Spain |
| LCOE | Laboratorio Central Oficial de Electrotecnia | Spain |
| CIEMAT | Centro de Investigaciones Energética, Medioambientales y Tecnológicas | Spain |
| SSM | Swedish Radiation Safety Authority | Sweden |
| IRA | Institut de radiophysique appliquée | Switzerland |
| PMOD/WRC | Physikalisch-Meteorologisches Observatorium Davos | Switzerland |
| Roth + Co. AG | Roth + Co. AG | Switzerland |
| MBW | MBW Calibration AG | Switzerland |
| TAEK | Türkiye Atom Enerjisi Kurumu (TAEK) | Turkey |
| MRC MI-UAL | Underwater Acoustics Laboratory | Turkey |
| LGC | LGC Ltd. | United Kingdom |
| NEL | TUV SUD LIMITED | United Kingdom |
| NMO | National Measurement and Regulation Office | United Kingdom |
| NGML | National Gear Metrology Laboratory | United Kingdom |
| NIBSC | National Institute for Biological Standards and Control | United Kingdom |
