International Standards and Conformity Assessment for all electrical, electronic and related technologies
Main title

SI Zone

International System of Units

Contributors to the SI


Base SI Units

SI base units and their interdependancy

IEC TC 25 (Quantities and units, and their letter symbols) maintains close collaboration with IEC TC 1 (Terminology) and is in constant liaison with ISO TC 12 (Quantities, units, symbols,conversion factors), OIML (International Organization for Legal Metrology - Organisation internationale de métrologie légale), ITU ( International Telecommunication Union) and BIPM (Bureau International des Poids et Mesures).