Luminous Flux in Lumen (LM) 
Technically spoken, the Lumen output describes the light visible to the human eye. However, the luminous flux in Lumen is not the only and most accurate form of measurement.
- Visible light can be partially blocked or dispersed within the lighting fixture.
- Visible light can be wasted due to fixture positioning or other factors connected to
  the installation of the lamp.
- Visible light can be emitted in a direction away from the task area.
- Filtering and lensing can waste visible light.
Illuminance in Lux (Lx) 
A more precise way to compare LED-fixtures with other lighting sources is a measurement of the delivered or usable light, which is technically called illuminance in Lux (LX). It describes the intensity of light falling onto a surface area without including wasted or non-directional light.  
 

 
Testing methods
A proper evaluation of the Lumen-value is indispensable for a successful illuminance of the task area. Most manufacturers measure the luminous flux of a lamp under a favorable ambient temperature of 25° Celsius. However, under other temperature conditions the Lumen output might differ remarkably. Please contact us for further information about different Lumen-values in different ambient temperatures.