LED Glossary

Color Rendering:

For a light source, the extent of the agreement between the perceived color of a surface illuminated by the source and that of the same surface illuminated by a reference source under specified viewing conditions, measured and expressed in terms of the chromaticity coordinates of the source and the luminance of the source in agreed spectral bands.

Color temperature:

The measurement of color expressed in Kelvin (K). The lower the Kelvin rating, the "warmer" or more yellow the light. The higher the rating, the "cooler" or more blue the light. (Place link here for chart image illustrating the Kelvin scale)


The sensation produced by brightness within the visual field that is sufficiently greater than the luminance to which the eyes are adapted. Glare can cause blurred vision, discomfort, headaches or loss in visual performance and visibility.


The density of luminous power, also called "illumination." One lumen of luminous flux uniformly incident on 1 square foot of area produces an illuminance of 1 footcandle. In SI units, one lumen of luminous flux uniformly incident on 1 square meter of area produces an illuminance of 1 lux.

Ingress protection rating:

The IP code or IP rating defined in the international standard IEC 60529 that classifies the level of protection that electrical appliances provide against the intrusion of solid objects or dust, accidental contact, and water.


The luminous intensity of any surface in a given direction per unit of projected area of the surface viewed from that direction.

Luminous efficacy:

The ratio of the total emitted luminous flux, in lumens, to the total electric power consumption in watts.

Luminous flux:

The rate of flow of light per unit of time, especially the flux of visible light, expressed in lumens.

Luminous intensity:

The luminous flux density per solid angle as measured in a given direction relative to the emitting source. The customary unit is candlepower, the SI unit is the candela.