SCL represents Hong Kong, China as an Associate of the General Conference on Weights and Measures (CGPM) of the Metre Convention. The Metre Convention is a diplomatic treaty between 51 nations to promote and ensure worldwide uniformity of measurements. It gives authority to the CGPM, the International Committee for Weights and Measures (CIPM) and the International Bureau of Weights and Measures (BIPM) to act in matters of world metrology, particularly concerning the demand for measurement standards of ever increasing range and diversity, and the need to demonstrate equivalence between national measurement standards. BIPM, under the direction and supervision of CIPM, is the world's authority responsible for the determination, realisation and dissemination of the International System of Units (SI).

SCL is a signatory of the "Arrangement for Mutual Recognition of National Measurement Standards and of Calibration and Measurement Certificates issued by National Metrology Institutes (NMIs)", which was drawn up by CIPM. There are presently 67 signatories. The CIPM MRA provides a framework for mutual recognition of the degree of equivalence of measurement standards of the participating NMIs and of the validity of their calibration and measurement certificates. It aims to facilitate free trade and eliminate technical barriers to trade. The degree of equivalence of SCL's measurement standards and SCL's calibration and measurement capabilities (CMCs) in the fields of electricity, time and frequency, thermometry, length, mass and related quantities (including force) are published in the BIPM Key Comparison Database (KCDB) as Appendices B & C of the CIPM MRA and internationally recognised. SCL is authorised by the International Bureau of Weights and Measures (BIPM) to use the CIPM MRA Logo in its calibration certificates (see details). Calibration certificates issued by SCL with the CIPM MRA Logo are recognised by over 180 NMIs and related organisations in 65 economies.

SCL is a Member of the Asia Pacific Metrology Programme (APMP) and a signatory of the APMP Memorandum of Understanding (MOU). APMP is a regional metrology organisation (RMO) comprising the NMIs in the Asia Pacific region, with the objective of co-ordinating activities aimed at the development of metrology and measurement standards in the region. It co-operates with other important international economic and technical bodies, including the Asia Pacific Economic Co-operation (APEC) and the BIPM on metrology matters.

SCL participates in the annual General Assembly of the APMP and the work of the following technical committees of the APMP:

(a) Technical Committee - Electricity and Magnetism (TCEM)
(b) Technical Committee - Length (TCL)
(c) Technical Committee - Mass and Related Quantities (TCM)
(d) Technical Committee - Quality System (TCQS)
(e) Technical Committee - Thermometry (TCT)
(f) Technical Committee - Time and Frequency (TCTF)
(g) Technical Committee - Acoustics, Ultrasound and Vibration (TCAUV)

The above technical committees have been very active in recent years as a result of the CIPM MRA. They play a very important role in co-ordinating the APMP inter-laboratory comparisons of measurement standards and in reviewing and evaluating the calibration and measurement capabilities (CMCs) as well as the quality systems of NMIs not only in the region (intra-regional review) but also other regions (inter-regional review) for inclusion into the technical schedules (i.e. Appendices B & C) of the CIPM MRA.

SCL is a full member of the National Conference of Standards Laboratories International (NCSLI) , an international metrology organisation having over 1500 member organisations, which are engaged in measurements, from different countries/economies around the world.