Lumen

The total amount of Visible Light that is emitted by a light source. The Lumen is the unit of measurement of Luminous Flux or Luminous Power. It is the photometric quantity that is analogous to Radiant Flux (measured in Watts). The Lumens emitted by a light source relative to the power it consumes (or emits over the entire Electromagnetic Spectrum) is equal to the Luminous Efficiency.