Light intensity per unit solid angle, measured in candelas (cd)
The emitted light intensity of a light source (reflector) which can be perceived by the human eye is measured with candela. A candela (cd) is thus the unit of measure for the light intensity (luminous flux (lm) per solid angle). A light source has a candela when the illuminance is one lux (lx) at a distance of one meter. So you can conclude: the higher the candela value, the brighter the emitted light.
Candela (cd) is divided into 1,000 millicandela (mcd). Candela specifications on a lamp package are usually always specified in conjunction with a beam angle. This beam angle (in °) indicates the angle at which the lamp emits the light and which served as the basis for the evaluation. Since light bulbs, drop and globe bulbs are all-radiant, it is difficult to determine a candela value which is why it’s typically not given.
However with reflectors we’re talking about directed light and the calculation of the light intensity is easier to determine. The smaller the beam angle of a reflector, the greater the bundling of the light and thus the candela value. Typical Candela values (determined usually at a distance of 1m) are between 3 and 12 candelas in apartments, between 10 and 20 candelas in offices and mostly between 60 and 300 candelas in object and shop window lighting.