IEVref: 112-02-10 ID: Language: en Status: Standard Term: candela Synonym1: Synonym2: Synonym3: Symbol: cd Definition: SI unit of luminous intensity, equal to the luminous intensity in a given direction, of a source that emits monochromatic radiation of frequency 540 × 1012 Hz and has a radiant intensity in that direction of 1/683 W/sr Note 1 to entry: The definition in the SI Brochure is: "The candela, symbol cd, is the SI unit of luminous intensity in a given direction. It is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540 × 1012 Hz, Kcd, to be 683 when expressed in the unit lm W−1, which is equal to cd sr W−1, or cd sr kg−1m−2 s3, where the kilogram, metre and second are defined in terms of h, c and ΔνCs." Note 2 to entry: This definition implies that 683 lm/W is the exact value of the luminous efficacy of monochromatic radiation Km. Note 3 to entry: The candela is one of the seven SI base units: second (s), metre (m), kilogram (kg), ampere (A), kelvin (K), mole (mol) and candela (cd). Publication date: 2020-12 Source: SI Brochure, 9th edition, 2019, 2.3.1, modified – The definition in the SI Brochure has been revised to comply with the IEV rules. Notes 1 to 3 to entry have been added. Replaces: 112-02-10:2010-01 Internal notes: 2020-12-10: Correction to Note 1 to entry: "minus" deleted in "monochromatic radiation of frequency 540 × 10−12 Hz". The French is already correct. JGO CO remarks: TC/SC remarks: VT remarks: Domain1: Domain2: Domain3: Domain4: Domain5: