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What is Illuminance?

  Measured in footcandles (fc) or lux (lx), illuminance refers to the density of incident luminous flux per unit area. This is the standard metric for lighting levels.  

Illuminance vs. Luminance

  Though the two terms are easily confused, illuminance and luminance measure very different things. 
  • Illuminance measures the amount of light falling on a surface. It is most commonly measured in footcandles or lux.
  • Luminance measures the amount of light emitting or reflecting off a surface. It is most commonly measured in candelas.