Lighting lexicon

Lumen (lm): this is the amount of light that is emitted from a light source (so the light output). A typical industrial LED lighting fixture would provide easily 1000 lm or more.

Lux (lx): this is the amount of light over a specific area (so the light intensity). A light source of 1000 lm would give 1000 lx on a surface of 1m².

Kelvin (K): this is the color temperature of a light source. It describes the visual warmth or coolness of the light emitted. A temperature of 3000K refers to warm white, where 5000K and above would be cool white or daylight white. Warm white would be used in household lighting, where cool white is used where crisp light for precision tasks is needed.

Luminous Efficacy (lm/W): is a measure of how well a light source converts electrical energy into visible light. It is expressed as a ratio of lumen (lm) to power input (Watt). Typical LED based industrial machine lights would have high values of ~155 lm/W.

Color Rendering Index (CRI or Ra): this index describes how the colour rendering of an artificial light source is compared to the colour rendering in sunlight. The higher the CRI/Ra value, the better the colour rendering of the light source. The colour rendering index can reach Ra values of up to 100, which corresponds to absolutely lifelike colour rendering (sunlight, black body radiation). Good machine lights will have an Ra value of 80+.