Candela
The SI base unit of luminous intensity in a given direction, defined by fixing the luminous efficacy of 540 THz monochromatic radiation to 683 lm/W.
Governing formula
Iv = dΦv / dΩ
SI unit
cd
In depth
Candela measures human-eye-weighted visual light intensity emitted per unit solid angle. A standard wax candle emits approximately 1 candela of luminous intensity in all directions.
Examples in the real world
A 100-Watt incandescent light bulb emits approximately 120 candelas of luminous intensity.