International cooperation

The aim is to harmonise global requirements concerning measuring instruments to the best possible extent, as the market for measuring instruments is large and the trade based on the reliability of measurements is in many cases international.

The international nature of the industry also requires international cooperation by authorities so that national perspectives concerning issues such as the conditions where measuring instruments are used are taken into account.

Tukes is actively involved in the operation of WELMEC (European Cooperation in Legal Metrology) and OIML (International Organization of Legal Metrology).


WELMEC (European Cooperation in Legal Metrology) is a European cooperation body in the field of legal metrology. Its members consist of authorities representing national legal metrology in the EU and EFTA Member States.

The purpose of WELMEC is to develop and harmonise the operations and interpretations of European authorities and inspection bodies in legal metrology and to promote communication between involved parties and those with an interest in the subject. WELMEC also advises the European Commission and the Council in the development of the Measuring Instruments Directive (MID). Among other things, WELMEC draws up guidelines for a harmonised application of directives concerning legal metrology. 

WELMEC’s decision-making body is a committee that consists of representatives of Member States and Associate Members and the observers of EUROMET, EA, OIML, and other regional organisations with an interest in legal metrology. Guidelines are prepared by WELMEC working groups that meet as needed.


OIML (International Organization of Legal Metrology) is an international organisation in the field of legal metrology, founded in 1955.  OIML cooperates with Metre Convention and BIPM (Bureau International des Poids et Mesures, or the International Bureau of Weights and Measures) for international harmonisation of legal metrology.  

OIML develops and publishes international standard-like recommendations, on the basis of which members can establish national legislation for various measuring instruments. The technical requirements of the draft of the European Measuring Instruments Directive (MID) are mostly identical to OIML recommendations.

The key points of OIML recommendations are:

  • scope of application, manner of application and terminology
  • metrological requirements
  • technical requirements
  • methods and controls to be used in testing and demonstration of compliance
  • test report format.

Cooperation agreements have been concluded between OIML and various institutions (such as ISO and IEC) in order to prevent conflicting requirements. This means that manufacturers and users of measuring instruments and testing laboratories can use the publications of OIML and other institutions at the same time.


Elsewhere on the Net

OIML International Organization of Legal Metrology
Catalog of OIML Publications: Recommendations OIML recommendations
WELMEC a body for the promotion of European cooperation in legal metrology
WELMEC: Guides