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What The Flux??? All About Automotive Lighting Terminology

Posted by Neal on 2018 Dec 17th

The automotive lighting world is filled with terminology, but does anyone know what it all means?

Here's some technical jargon that you can use to impress your friends.

Luminous Flux:

  • The complete light output from a single light source in every direction.
  • Measured in Lumens (lm)

Luminous Intensity:

  • The portion of the luminous flux radiating in a single direction.
  • Measuers in Candela (cd)


  • Lumens per square meter.
  • The brightness of a bulb in every direction.
  • Measured in Lux (lx)


  • Candela per square meter.
  • The brightness of a bulb in a single direction.
  • Measured in Candela per Square Meter (cd/m2)

Luminous Efficiency:

  • How efficient a bulb is at turning electricity into light.
  • The more efficient a bulb, the brighter it will be per watt of electricity.
  • Measured in Lumens per Watt (lm/W)

Color Temperature:

  • The color of lights is measured in Kelvin.
  • The higher the 'temperature', the more blue and less red the light is.
  • 2700K is considered a warm light.
  • 5000K is similar to daylight and is also the color of most OEM Headlights.
  • 6000K is a cooler pure white light.
  • 8000K is a deeper blue white, but with less light output.